Engine Sputter is back

[trayson]

So, After I installed my surf system on my 92 Sunsport (in June), I found it was spraying water onto the gas tank breather valve. Sure enough, it coughed and sputtered part way into the evening and I couldn't drive it with a decent load on the engine. If I went over 10mph, it would make a "bump bump bump" sound and too much more throttle and it would sputter and cough. I've had trouble with the gas breather valve before as the OEM location was getting water when I slammed the boat for surfing. I moved it to the starboard side and didn't really have any major issues until I installed the surf system that was spraying water right at the vent. Obviously, I moved the vent again.

So, when that sputter happened back in June, I put some Heet in the tank, then drained the whole tank (well as much as I could using an electric fuel pump--The boat is parked on a bit of a slope, so the hose in the tank got most of the gas out). I then changed the fuel filter. Finally, I filled up the tank with new gas. When I next used the boat, it did have the same inability to handle much of a load for the first few minutes (obviously the fuel in the system). But then it ran normal and I'd only had a brief hesitation maybe a couple times since (and I've done probably a good 5 to 10+ trips since then). I've also moved the fuel tank breather to way up by the front windshield to get it so it's away from all the water at the stern that my boat sees when surfing. All the gas that I drained out of the boat (around 22 gallons) I put into my 2000 Jeep Wrangler and it seemed to consume it just fine.

Today, we went out and played for quite a few hours. Surfed a bunch. Then we drained our bags and motored to drop off our friends and start heading back to the launch. We did a good 5 to 10 minutes at 25 to 30mph. Then out of nowhere, hesitation cough sputter. And the identical scenario where I couldn't go more than 10 to 12mph with out hearing the engine making a "bump bump bump" noise and the same sputter cough with more throttle.

So tonight, I've again drained as much gas as I could out of the boat (around 20 gallons) and put it into my wife's Honda Ridgeline. I went on a test drive with the Ridgeline and it drove completely normal. I've also pulled the fuel filter and will throw another new one in before the next outing. I'll fill the tank with new gas, and throw a bottle of Heet in there just in case.


It seems like these are all classic "water in the gas" symptoms, but I'm a little stumped as to why this is happening again. What am I missing? I have the PCM
Pro Boss with the protec. I'd Really like this saga to come to an end...

[SquamInboards]

When you said it happened last after a long ride (5 - 10 min) at relatively high speed, I was thinking it sounds like a fuel line collapsing internally. Pretty hard to diagnose, other than running it that same way on an external fuel tank to see if the problem goes away. But replacing the main fuel line isn't that bad of a job, maybe it's worth doing, unless you have done it very recently. Just a thought. Ethanol blended fuel is really tough on old fuel lines. But your symptoms make sense, in that it only happens when you're drawing a large volume of fuel for a long continuous time. But that scenario also can stir up crap in your fuel filter, or any residual water too.

[Cusefan78]

The easy way to check the fuel system for a blockage is to pinch the return line and see if it runs better. If that's the case you have a blockage somewhere or the pump is getting weak

[wotan2525]

The easy way to check the fuel system for a blockage is to pinch the return line and see if it runs better. If that's the case you have a blockage somewhere or the pump is getting weak

I don't think his engine has a return line, does it?

[haugy]

Self-induced suicide from embarrassment?

[trayson]

The easy way to check the fuel system for a blockage is to pinch the return line and see if it runs better. If that's the case you have a blockage somewhere or the pump is getting weak


I don't think his engine has a return line, does it?

Correct, I don't have a return line. I have only 3 hoses on my fuel tank.

Big hose for fuel Filler
Line for fuel breather/vent
Line from tank to engine




When you said it happened last after a long ride (5 - 10 min) at relatively high speed, I was thinking it sounds like a fuel line collapsing internally. Pretty hard to diagnose, other than running it that same way on an external fuel tank to see if the problem goes away. But replacing the main fuel line isn't that bad of a job, maybe it's worth doing, unless you have done it very recently. Just a thought. Ethanol blended fuel is really tough on old fuel lines. But your symptoms make sense, in that it only happens when you're drawing a large volume of fuel for a long continuous time. But that scenario also can stir up crap in your fuel filter, or any residual water too.

I suppose I could replace the line. But I've run it harder and longer many times since. And this time I did sit for 10+ minutes and it was still right there. What's kind of compelling that it's the water in the fuel thing is that in June when I drained my tank and refilled with new fuel, it ran poorly for the FIRST few minutes then was completely fine from there on out. So that tells me that draining the fuel was the solution last time and that the residual fuel in the line needed to get cleared out before the engine was happy again...

[phathom]

When you said it happened last after a long ride (5 - 10 min) at relatively high speed, I was thinking it sounds like a fuel line collapsing internally. Pretty hard to diagnose, other than running it that same way on an external fuel tank to see if the problem goes away. But replacing the main fuel line isn't that bad of a job, maybe it's worth doing, unless you have done it very recently. Just a thought. Ethanol blended fuel is really tough on old fuel lines. But your symptoms make sense, in that it only happens when you're drawing a large volume of fuel for a long continuous time. But that scenario also can stir up crap in your fuel filter, or any residual water too.


I second this idea. I have had issues like this happen with vacuum lines and fuel lines over the years, mainly on older vehicles, mostly carbureted. They can collapse from excessive heat and solvent wear making them weak.
It's a cheap and relatively easy fix. I think it's also about time we crack that carb open for a good cleaning and possibly a rebuild.
I think I've told you about the issue we had on our boat where it turned out a small piece of pencil lead had fallen in the gas tank somehow, gotten sucked through the lines into the carb and would intermittently clog the carb up. It would run fine 9/10 times, but every now and then it would find itself in the right position to block the fuel and you'd get stuttering and surging. Let the boat settle for a bit, try again and it was fine until it got in there again. The problem only occurred under load. You could have some debris in the carb or fuel line.
Let me know, I've rebuilt several carbs and will be happy to lend my expertise.

[Cusefan78]

I had a problem in the spring with a clogged filter. Changed it ran fine for a few days then the sputter came back. Was told to replace the filter again and haven't had a problem since. I would check also to see if you have a pickup filter on it.

[trayson]

I had a problem in the spring with a clogged filter. Changed it ran fine for a few days then the sputter came back. Was told to replace the filter again and haven't had a problem since. I would check also to see if you have a pickup filter on it.

Like something that could exist on the fuel sender unit that's on the tank itself?

[wotan2525]

The pickup filter would be a sock/element inside the tank. I doubt you have one, but it is possible. You'd need to pull the fuel sender unit so that you could get access to try and see in there with a light.

I'd change your fuel/water separator, again and replace any in-line filters. Marine fuel line would be cheap to replace but it doesn't sound like that is your problem.

[trayson]

The pickup filter would be a sock/element inside the tank. I doubt you have one, but it is possible. You'd need to pull the fuel sender unit so that you could get access to try and see in there with a light.

I'd change your fuel/water separator, again and replace any in-line filters. Marine fuel line would be cheap to replace but it doesn't sound like that is your problem.

The filter that I have is this one. Napa Gold 3110 Fuel Filter:
http://i.ebayimg.com/00/s/MTk4WDI1Mg==/$(KGrHqN,!jcE9KPL!smzBPk2s6BMSg~~60_35.JPG

Also, it has a brass plug at the bottom of the housing. Should I be draining this regularly?

[Moor]

I had a similar problem on a old I/O volvo penta dual carb set up. went through the ENTIRE fuel system 3 times... i had no fuel / water seperator on the boat, i ended up having water in the carb float bowls. i drained both carbs and she ran great for the next 3 years. I don't know if this is your prob, but since its easy enough to crack a few bolts loose on your Holley and drain it, i figured id throw it out there. Hope you get it fixed soon...

[CJD]

Water in the tank is a real pain. It hides in cracks and crevasses...filters...carb bowls...etc, just waiting for the perfect conditions to get sucked into the right place and choke you motor. Fuel pick-ups are usually near, but not at the bottom of the tank. Using the pump to remove the water is only getting what the pickup can reach. There is always more waiting to slosh into the pickup when waves shake your boat and stir it up.

Use an ample amount of fuel additive made to absorb water. It will gradually emulsify the water in your system and allow it to harmlessly pass through the motor. The alternative is to drain the tank and remove the sender plate to allow all residual fuel and water to evaporate. A real pain, so I'd go for the fuel additive first, and frequently.

[wotan2525]

The filter that I have is this one. Napa Gold 3110 Fuel Filter:
http://i.ebayimg.com/00/s/MTk4WDI1Mg==/$(KGrHqN,!jcE9KPL!smzBPk2s6BMSg~~60_35.JPG

Also, it has a brass plug at the bottom of the housing. Should I be draining this regularly?

That looks like a regular filter. I'd add this fuel/water seperator to your system. You can just cut your line and add one in-line. NAPA sells a kit that has both the filter and the mounting bracket thing. I can't find it on their website but believe they have it in their "marine" section.

[trayson]

That looks like a regular filter. I'd add this fuel/water seperator to your system. You can just cut your line and add one in-line. NAPA sells a kit that has both the filter and the mounting bracket thing. I can't find it on their website but believe they have it in their "marine" section.

So you're saying that the filter that I have on my engine might not be doing water/fuel separation at all? It's the orange one at the very bottom of this pic:
https://lh4.googleusercontent.com/-AS0RwdGnHMw/Uc5kEvFzMoI/AAAAAAAAONo/h9GRS7FMme8/s800/20130628_201501.jpg

The canister looks like the water/fuel separators I see online, complete with a drain at the bottom. But this one does look like i thas paper elements inside the filter itself.

So, if I get a fuel/water separator, then where would I mount it? Before the existing filter or after?

[trayson]

From what I've found online, the Napa 3110 that I have should function as a fuel/water separator... ???

[SquamInboards]

A fuel filter can be designed to remove water without having a drain; I do believe the NAPA filter is designed to remove water, and the advantage of the drain is you can check for water without removing / dumping out the filter. So next time you have the issue, if it's caused by water in the fuel, there should be some water/fuel mix in that filter housing. You might have to let a clear jar of the drained fuel settle for a while before you see the water - it doesn't take much to cause an issue, and it takes a while to separate when it's all shaken up. Like, let it sit for an hour or more.

If your fuel line was collapsing, it might not happen every time you run it hard, and it might stay partially collapsed after sitting for a few minutes. Next time it happens, you could switch over to a little external tank hooked right up to the pump and run it hard on that right away; if the problem goes away immediately that points to a supply issue. If it sputters for a while and then clears up, it points to water in the tank or another blockage.

My fuel pickup in the tank has a small screen in the bottom, which got clogged up the first time I used ethanol fuel in the tank. It was just a wire screen. If there was debris in the tank it could be getting sucked up into the screen, and that wouldn't happen every time you run it hard, it would be random chance, and if it's floating debris, it would happen more as your tank got lower, in theory. The problem with checking that, is the debris could fall off when you take it out of the tank. But if you carefully removed it right when you have the issue, it could be clogged up still. As with the last time, the issue remained after 10 minutes of sitting, with fuel no doubt sloshing around in the tank.

[Moor]

^ good idea about running on a external tank next time the proplem happens. Great way to pinpoint where the problem is. If it runs fine on the external tank, look into a clogged fuel pick up, collapsed fuel line or water in fuel. if it runs bad on the external tank, check fuel pump and carb. I believe your napa filter is a water seperator, pretty sure i had the same one on an old Ski nautique i used to own. Water in the fuel can be a real pain in the gas. Might be best to remove the tank and completely drain and clean. Water is heavier than gasoline and will always settle in the bottom of the tank, where your fuel pick up is....

[whammond]

I'll try and be of some help. I have a '92 comp, 351 proboss, mine looks exactly the same. I have the same fuel filter housing you have, but I am not using that filter you listed. The one I have been using is listed below. My understanding of how this works is that the gas goes into the housing, through the filter, and out the housing to the fuel pump. Water has a higher density than gasoline, so it is supposed to be trapped and will fall and begin to collect in the bottom of the housing. The filter is also supposed to capture dirt and whatnot also of course. You'll notice there's a bolt in the bottom of the housing (mine is a total PITA to get to because its so close to the hull and I have no clearance), my understanding is that the design is intended to simply loosen this bolt every once in a while and let the collected water (and likely a little bit of gas) drain out into the bilge.

My fuel filter:
http://www.skidim.com/prodinfo.asp?number=R080008
http://www.amazon.com/Fram-C1110PL-Fuel-Oil-Filter/dp/B000AMW0LK

Now I am not sold or am too much of a believer in this fuel-water seperator system from the early 90s. I would like to upgrade to something like this, my friend has one in his shamrock (also has a PCM 351...cool boat) and it is the bees knees. My problem is that I do not have the space to switch to this filter/housing combo as it is too tall (see my PITA comment above). I would have to rig up some kind of mount to raise the top of the fuel filter from the existing mounting location. I would absolutely recommend switching to this if you can, its nice to be able to see the water it is collecting and drain it separately.

http://www.amazon.com/Sierra-International-18-7932-Marine-Separator/dp/B001F0GQQ6

I would definitely second taking a external tank and hooking it straight to the fuel pump (or the out hose of the fuel filter housing, skipping the filter). This will help troubleshoot your problems.

One last thing (and I hope this isn't it). My boat underwent some really weird sputtering, then had issues starting while hot, and then starting at all. It was the protec ignition going bad, and basically the coil packs leaked out and it died so I had to do the whole electronic distributor conversion kit.

[wotan2525]

Yep -- That looks like a fuel/water seperator but the filter is different than what I've got in mine. I'd drain it because it might be full of water and that would be your problem. If you can take the entire filter off with an oil-filter wrench and then drain it into a glass container, you can see how much water vs. gas is in there.

[whammond]

FYI mine doesn't come off with an oil filter wrench. Mine is that bolt in the top you can see in the picture. Take that bolt out and it slides out underneath.

[trayson]

FYI mine doesn't come off with an oil filter wrench. Mine is that bolt in the top you can see in the picture. Take that bolt out and it slides out underneath.
mine too.........

[trayson]

When you said it happened last after a long ride (5 - 10 min) at relatively high speed, I was thinking it sounds like a fuel line collapsing internally. Pretty hard to diagnose, other than running it that same way on an external fuel tank to see if the problem goes away. But replacing the main fuel line isn't that bad of a job, maybe it's worth doing, unless you have done it very recently. Just a thought. Ethanol blended fuel is really tough on old fuel lines. But your symptoms make sense, in that it only happens when you're drawing a large volume of fuel for a long continuous time. But that scenario also can stir up crap in your fuel filter, or any residual water too.

How long of a run of hose would I need to replace the fuel line? I'd prefer not to remove my old hose until get the new hose so I can use the old hose to fish it through...

[ssa]

I believe skidim sells it in 5 foot increments. I replaced mine over the winter and 15 feet did it. I believe I had about 2 feet left.

[whammond]

Its not bad to fish it through. Just went around the fuel tank and fed up the bilge. One thing you might wanna check is the right-angle hose barb at the top of the fuel tank, mine was corroded and needed to be replaced. PO must've let is sit with untreated ethanol gas.

[Supra-in-steamboat]

Agree on the external gas can, start there. I do empty the fuel filter canister a few times a season. If the triple bump comes back with the external tank you know to look at your carb or...does your boat have "limp" mode? Some Pro Boss set ups came with, pardon the terminology, coil packs and sensors. I helped a friend with a 92 last year same issue. Still had issue after external tank was used so we used a jumper wire to individually bypass the sensors to rule them out (4) I believe. Still had issue so pulled carb bowls, emptied and replaced. Still had issue, replaced carb power valve. No more issue. Hope this helps. Good luck.

[trayson]

So I added a bottle of heet into the tank, then drained it and put the fuel into my wife's truck. (which has consumed the fuel with no issues).

I filled the tank with new fuel, but put in 2 bottles of HEET for good measure to go with the new E10 gas. Since I wanted to keep some things consistent for comparability and troubleshooting, I gave it 87 octane again like I have all year. My old roomie was a lifetime ford mechanic and build ford drag racing engines. He confirmed that what PCM said was accurate, that our engines are designed to run on 87 and unless we're running high compression or doing something to advance the timing, that 87 is all it needs.

I changed the fuel filter (water separator) and also checked the filter (screen) that's on the carbauerator itself and it looked great. I sprayed that screen with carb cleaner for good measure. Likewise, I sprayed a bunch of carb cleaner in the engine while it was running on the garden hose with the new gas in it.

It seems like this stuff worked??? I didn't have any problems last night and burned about 9 gallons of gas. I was going at speed most the time.

I guess we'll see what happens from here on out...

[SquamInboards]

One last thing (and I hope this isn't it). My boat underwent some really weird sputtering, then had issues starting while hot, and then starting at all. It was the protec ignition going bad, and basically the coil packs leaked out and it died so I had to do the whole electronic distributor conversion kit.

I don't know how I missed this since you have a 1992... do you have the ProTec ignition? If so, this is a common failure point and can cause weird run issues. Although your issue does seem to point to fuel, the fact remains that most people with the ProTec ignition system can be trouble.

That being said, if you can replicate the problem and find that it runs well on an external tank, that will be a nail in the coffin of "it's something on the engine" and then I'd be thinking about the ignition system.

But let's all hope that you've solved it!

[CJD]

Don't feel bad about all the work. Twice in my life I have spent $thousands on a cars I've had that sputtered and threw codes...only to find that a tank of bad gas caused the whole episode. Water in the gas is one of the hardest things to diagnose, and even harder to get out of your system. It collects everywhere. I think you did good by covering all the nooks it was hiding in at one time!

[trayson]

So the boat ran great, consuming 9 gallons of gas on Wed evening with NO issues. Topped off the gas tank afterwards.

Then today we drove 15 minutes to our spot. filled up the bags and started to get in our first surf. Made it partway through the first ride and the problems resurfaced. I figured out that the "bumping" sound was actually the exhaust. If I gave it more throttle after the exhaust started making the bump sound, it'd cough and sputter. So we stopped. We anchored and let the kids play on the beach. I took off my fuel filter and drained the gas that was in the bowl into a water bottle. Put the boat back together and had lunch. Then we drained the bags and the engine seemed to run fine. Took about 1/2 of a wakeboard run and then the engine started with the same problems. Came back in the boat and it wouldn't let me go more than 12 mph without problems.

So, on a whim, I dumped a bottle of HEET that I had in the boat into the gas tank. The boat was literally off for as long as it took me to unscrew the gas cap and dump the bottle in. I started the boat up and it drove FINE the rest of the way back to the launch (15 minutes at 20 to 30mph). And even performed fine for a 6 minute run pulling my friend and his son on the tube. We had to get off the water after that. Only went through 5 gallons of gas today.

It honestly doesn't make sense to me that the Heet could have worked virtually instantly. So I'm wondering if the gas tank isn't venting properly (because I extended the vent line to the front to protect it from water when surfing). Maybe the thing that helped me get back to the dock was simply cracking open the filler cap on the gas tank?????

At this point, I'm ready to replace the fuel line, change out my Pro Comp coils to an HEI distributor, and anything else that I can think of. I will note that I have NOT taken the fuel sender unit out of the gas tank so I don't know if I'd find anything there. Worth a look???

[Kma4444]

Sounds like vapor lock to me. Getting more and more common. Fuel used to be formulated to resist that as cars with fuel pumps that pulled fuel from the tank, around hot things, over hot asphalt, would boil the fuel and not be able to pump the vapors. Runs the float bowls low an fuel and you get the lean condition you describe. Today's cars, with pumps in the tank and high pressure fuel systems will not suffer that malady. It's frustrating that we are having to relearn how to cure vapor lock as it had become almost extinct. The new alcohol fortified fuels are even more prone to boiling under heat and vacuum.

You need a pump as close to the tank as you can get it. If it's vapor lock you will fix it. Just buy a cheap electric pump and wire it through the ignition switch. An extra plus is, it makes starting after sitting long enough to evaporate the fuel out of the carb really quick. When you turn on the ignition, it fills the float bowls. No having to crank and crank to get the mechanical pump primed and fuel up to the carb.

[SquamInboards]

Do you have a check valve inline on your vent hose? The length shouldn't really matter, so long as it's able to pull air through.

I really think running the boat on an external tank the next time you have the issue would go a long way toward diagnosing the problem, or at least pointing you in the right direction (supply-side or delivery-side).

I agree that probably opening your gas cap was the thing that made the difference that time, not the additive. I suppose you could also try just opening the cap next time it happens.

[wotan2525]

Is there a loop or slack in your vent anywhere? Running it all the way to the front of the boat makes me think there is a low spot that could pool gas and not allow it to vent properly.

[trayson]

Do you have a check valve inline on your vent hose? The length shouldn't really matter, so long as it's able to pull air through.

I really think running the boat on an external tank the next time you have the issue would go a long way toward diagnosing the problem, or at least pointing you in the right direction (supply-side or delivery-side).

I agree that probably opening your gas cap was the thing that made the difference that time, not the additive. I suppose you could also try just opening the cap next time it happens.

No check valve

So what are you thinking? Disconnect the fuel line that goes out of the fuel filter from the fuel pump and put that into a gas can?

https://lh5.googleusercontent.com/-V-vCIc8V8Sk/Uc5kI-B3PgI/AAAAAAAAONw/UgOkTgoRTBc/s800/20130628_201441.jpg


Is there a loop or slack in your vent anywhere? Running it all the way to the front of the boat makes me think there is a low spot that could pool gas and not allow it to vent properly.

There is some slack in the vent line. It's a run that goes from the gas tank up to by the windshield so it's be hard to get a perfect slope on it...

[trayson]

Sounds like vapor lock to me. Getting more and more common. Fuel used to be formulated to resist that as cars with fuel pumps that pulled fuel from the tank, around hot things, over hot asphalt, would boil the fuel and not be able to pump the vapors. Runs the float bowls low an fuel and you get the lean condition you describe. Today's cars, with pumps in the tank and high pressure fuel systems will not suffer that malady. It's frustrating that we are having to relearn how to cure vapor lock as it had become almost extinct. The new alcohol fortified fuels are even more prone to boiling under heat and vacuum.

You need a pump as close to the tank as you can get it. If it's vapor lock you will fix it. Just buy a cheap electric pump and wire it through the ignition switch. An extra plus is, it makes starting after sitting long enough to evaporate the fuel out of the carb really quick. When you turn on the ignition, it fills the float bowls. No having to crank and crank to get the mechanical pump primed and fuel up to the carb.

I bought a cheap electric pump for $40 that I've been using to drain the gas tank (when I had to remove the tank to install my transom lights and also my Surf system). Is that all I'd need? I'd just put it inline then near the tank and wire the positive to the ignition circuit. seems easy enough.

[whammond]

So what are you thinking? Disconnect the fuel line that goes out of the fuel filter from the fuel pump and put that into a gas can?


Yep, you want a line straight from the external gas can into the mechanical fuel pump. That existing line from the fuel filter housing to the fuel pump is pretty short, but it may be long enough.

You may have to get some extra fuel line anyways to do this test. I'd just go ahead and replace your fuel lines. It really isn't that difficult, just a little annoying because mine had all these plastic clips w/ screws that held the fuel line close to the side of the bilge. Assuming you haven't replaced them since you got the boat, i'd just do it and have peace of mind and be done with your lines.

Now i'm going to start spitballing: Concerning the potential vapor lock issue, (essentially your gasoline boiling somewhere along the way, typically inside the fuel pump). What degree thermostat are you running, 143 or 160? And following that, what's your typ. operating temperature? I have the 143 in mine. You could always try running your engine cooler, and see if that helps the issue. Having tried both degree thermostats (and one time putting a thermostat in upside down), the engine temp is obviously related to the temp inside the dog house. If you keep the engine cooler, the fuel pump, etc. stays cooler. As a test, you could just take the thermostat out and run it around for a while and see if the problems resurface. I wouldn't suggest doing this all the time as your engine isn't meant to continue running that cold.

It also could just be the fact that your fuel pump is beginning to give way and just isn't creating the amount of pressure required at higher rpms. I replaced mine, and I took apart my old one and the seals and gaskets on it were in bad shape. I'm guessing from gas w/ ethanol in it. You could always pull your fuel pump and open it up and see what it looks like.

Diagnose and replace the cheap things first....rinse and repeat.

[SquamInboards]

So what are you thinking? Disconnect the fuel line that goes out of the fuel filter from the fuel pump and put that into a gas can?



If you have any friends with small 4-stroke outboards you could ask to borrow their fuel tank (assuming it's removable). Then you could probably use the line right from that tank, take off the outboard connector and put the hose right onto the fuel pump and hose clamp it for your testing purposes. It is a little depressing to see how fast an outboard tank gets drained by one of these engines, actually.

As you have been wisely trying to eliminate things without throwing expensive parts at it, this is a good way to narrow down your focus. I wouldn't touch the distributor until I was certain the problem would occur with the boat running on a completely different fuel source. Same goes for the fuel pump, and for the added electric fuel pump. There are a lot of good ideas being suggested here, I'm just suggesting a way to narrow down which one might be right.

[trayson]

Yep, you want a line straight from the external gas can into the mechanical fuel pump. That existing line from the fuel filter housing to the fuel pump is pretty short, but it may be long enough.

You may have to get some extra fuel line anyways to do this test. I'd just go ahead and replace your fuel lines. It really isn't that difficult, just a little annoying because mine had all these plastic clips w/ screws that held the fuel line close to the side of the bilge. Assuming you haven't replaced them since you got the boat, i'd just do it and have peace of mind and be done with your lines.

Now i'm going to start spitballing: Concerning the potential vapor lock issue, (essentially your gasoline boiling somewhere along the way, typically inside the fuel pump). What degree thermostat are you running, 143 or 160? And following that, what's your typ. operating temperature? I have the 143 in mine. You could always try running your engine cooler, and see if that helps the issue. Having tried both degree thermostats (and one time putting a thermostat in upside down), the engine temp is obviously related to the temp inside the dog house. If you keep the engine cooler, the fuel pump, etc. stays cooler. As a test, you could just take the thermostat out and run it around for a while and see if the problems resurface. I wouldn't suggest doing this all the time as your engine isn't meant to continue running that cold.

It also could just be the fact that your fuel pump is beginning to give way and just isn't creating the amount of pressure required at higher rpms. I replaced mine, and I took apart my old one and the seals and gaskets on it were in bad shape. I'm guessing from gas w/ ethanol in it. You could always pull your fuel pump and open it up and see what it looks like.

Diagnose and replace the cheap things first....rinse and repeat.

Undoubtedly original fuel lines.

That said, my engine rarely seems to run hot. Not that I'm really that good about mentally logging what the temps are. But I know that whenever I look, I think it's below the halfway mark on the temp gauge.

I'm thinking that the fact it ran well after opening the gas cap might be of interest...

[SquamInboards]

I'm thinking that the fact it ran well after opening the gas cap might be of interest...

... yeah that. I forgot to add: since you "solved" the issue last time when you opened the gas cap, try that next time it happens. Just a quick open, close, and fire it back up. To the lake! More research required...

[trayson]

... yeah that. I forgot to add: since you "solved" the issue last time when you opened the gas cap, try that next time it happens. Just a quick open, close, and fire it back up. To the lake! More research required...

Without a doubt I'm going to see if that makes it better. if so, that's certainly worth pursuing. I probably won't be on my boat until the weekend though. yesterday was on someone else's v-drive and tonight is the same, someone else's boat. Tues - Thurs is supposed to rain. So we'll see what happens when I get back on my boat.

[Kma4444]

That's exactly right. Just add your electric pump back close to the tank, or at least before the mechanical pump.

[trayson]

That's exactly right. Just add your electric pump back close to the tank, or at least before the mechanical pump.

So, let's say that I needed to remove my gas tank in the future. If I had the electric pump mouted near the tank, could I just disconnect the output hose from the electric pump and connect a line to it flowing into a gas can and turn on the ignition and watch the electric pump drain the tank?

I'm sure at some point I'll have to remove that tank again (as that's the only access to my rudder packing).

Just curious.

[Cusefan78]

Yes you can do that. I would run it very long that way. But you could do a tank let it sit and cool then do another and so on. I would be afraid of running it for a long period and burning it out. With that said I once had a mechanic who insisted I needed to drain a full tank of gas out of my baja. Mind you I just put the gas in two days before I needed service. He then tried to charge me for 5 hours labor at 135$ an hour to have his guy watch the pump. I really wanted to kill this guy. FYI this service was for a tuneup. Last time I used that mechanic and I made sure everyone on the lake new not to use him.

[SquamInboards]

Correct me if I'm wrong, but wouldn't you also need something to tell the pump to shut off when the engine is not running, but the key is still in 'ignition' position, like it would with any fuel injection system? I'm talking about if you were to install it permanently into your system.

[chris young]

I have to agree. I don't know this for a fact, but I've always assumed that the reason why they are wired this way is that they can run all day long as long as they are pumping fuel, but when the pressure builds and there's no fuel flow it will kill the pump. I've got a dead one out of my car that I'm planning to see if I can get running again to use as a fuel transfer pump.

[wotan2525]

Those are fuel injection (high pressure) pumps. These low pressure pumps can sit pressurized and be just fine. I have a super small electric pump in mine (no mechanical pump) and I've never had a problem.

[trayson]

The one that I have looks like this... not sure if it's the same exact model, but it might be.

http://static.summitracing.com/global/images/prod/mediumlarge/pfs-10700_w_ml.jpg
http://www.summitracing.com/parts/pfs-10700?seid=srese1&gclid=CjwKEAjw9qafBRCRiYrL4-fpuFkSJACvocQ1F-C6E7PlB8oKHbBfOnOiyr_ueKTa5RaknK_oi47N_RoCfIbw_wcB

[wotan2525]

The one that I have looks like this... not sure if it's the same exact model, but it might be.

http://static.summitracing.com/global/images/prod/mediumlarge/pfs-10700_w_ml.jpg
http://www.summitracing.com/parts/pfs-10700?seid=srese1&gclid=CjwKEAjw9qafBRCRiYrL4-fpuFkSJACvocQ1F-C6E7PlB8oKHbBfOnOiyr_ueKTa5RaknK_oi47N_RoCfIbw_wcB

I think before I'd mess with your lines I'd verify if it's vapor lock or a vent issue. People on this board seem pretty quick to point the finger at vapor lock, when it seems like you have tons of evidence pointing towards a venting issue.

That pump would be OK to use as either a replacement or an addition to your mechanical fuel pump. It can be put right in line with the existing fuel line and can be wired into the ignition solenoid to only run when the key is on.

[ssa]

Coast guard regulations require that the pump only run when the engine is running. My carbureted 95 has a pressure switch plumbed into the oil gallery to kill the pump. Doesn't cost much and is cheap insurance.

[trayson]

I think before I'd mess with your lines I'd verify if it's vapor lock or a vent issue. People on this board seem pretty quick to point the finger at vapor lock, when it seems like you have tons of evidence pointing towards a venting issue.

That pump would be OK to use as either a replacement or an addition to your mechanical fuel pump. It can be put right in line with the existing fuel line and can be wired into the ignition solenoid to only run when the key is on.

I agree that the next trip out I'll try the SIMPLE test of cracking the gas cap to equalize pressure. That's the easiest test I can do. Even easier than running off an external tank.

Rain for the next few days. we'll continue to monitor and troubleshoot.

[Moor]

if you use that electric pump, you may want to add a low pressure fuel regulator. Most electric pumps run a much higher psi than the 5-7psi our carbs/mechanical pumps run. I converted to an electric pump on my old muscle car and found out the hard way i needed a low pressure fuel regulator when the gas was pouring out of the top of may carb lol.

[trayson]

So, took the boat out today. Went through over 14 gallons of gas. No issues except for the boat did feel like it was surging a bit when I was letting my son drive at about 15mph. He had the throttle fixed in one spot. Beyond that, it ran fine. Wakeboarding, slalom pulls, cruising, slow tubing, floating, and finally surfing. No issues...

That said, I did come prepared with a length of new fuel hose and 2 gallons of ethanol free premium in a gas can just in case I'd need to hook that up to the fuel pump to verify whether it was upstream or downstream of the pump...

We'll probably go out again on Monday evening, so we'll see if anything materializes...

[MDVols]

I was surfing with my gas vent under water and when we were done my boat started running like you described. I drained all the fuel and filled
With non ethanol, new plugs, button, and distributor cap still the same. Finally I was so mad I ordered a brand new carb cause the old one was gummed up and I didn't care
For vacuum secondaries, ran a little better but didn't fix it. Talk to my mechanic he said the on thing he could think of was an ignition problem. So I went and bought a $40 ignition coil plugged it in and it fired up like a nascar.

But just a question, now I am paranoid about surfing with a lot of people cause my boat sets lower in the water, does the gas breather let water back in or does it work like a check valve.


Bam! Supra, what's that!

[trayson]

I was surfing with my gas vent under water and when we were done my boat started running like you described. I drained all the fuel and filled
With non ethanol, new plugs, button, and distributor cap still the same. Finally I was so mad I ordered a brand new carb cause the old one was gummed up and I didn't care
For vacuum secondaries, ran a little better but didn't fix it. Talk to my mechanic he said the on thing he could think of was an ignition problem. So I went and bought a $40 ignition coil plugged it in and it fired up like a nascar.

But just a question, now I am paranoid about surfing with a lot of people cause my boat sets lower in the water, does the gas breather let water back in or does it work like a check valve.


Bam! Supra, what's that!

My understanding is that the valve (at least on my boat) is an anti splash valve. It doesn't have a check valve in it.


These vents help prevent water from entering the fuel tank, yet allow air to vent freely, during normal sea conditions and washdowns. This eliminates the need for an anti-siphon loop in the vent hose. Meets ABYC Standard. Installs easily and permanently. Made of flame-retardant black plastic with choice of black, white, or stainless steel vent head/cover.

Mine looks like this:
http://www.iboats.com/mall/image/vendor/7/big/21382_0.jpg

[Moor]

I'm pretty sure its just a vent "valve" i don't think there is a check valve in it to prevent water from coming back in, but im not 100% sure

[trayson]

Went out again last night. only used about 6 gallons though. (seriously, only $25 in gas! that's what happens when I skip adding 1700 pounds worth of surf ballast and just let my buddy lineride on 1 little under the seat sack).

No issues last night either. Go figure.