Another fuel issue - UGH!!

[svahle]

Like many others, I am chasing a fuel problem and have nearly run out of ideas. So, I thought I'd make my own thread and see if anyone has any thoughts or suggestions. I'll go through the problem and all I've done to try and fix it. It is an 86 Sunsport with the PCM 351.

The problem: Once in a while, at higher RPMs (above 3000), the boat will starve for fuel and die. This may happen once in a day, or it might happen several times. On all but one occassion I have been able to re-start the boat. With the exception of this intermittent "hiccup" the boat runs flawlessly (starts easy, idles great, accelerates with no dead spots, etc. etc.). On the occassion the boat died and wouldn't restart, I poured fuel directly into the carb and it fired instantly. I did this a couple of times with identical results. In short, it is a fuel problem and not a spark issue.

Things I've done that didn't help:

1. Replaced the mechanical fuel pump. This didn't help. Thinking the issue might be related to the fuel pump eccentric that actuates the fuel pump arm, I bypassed the mechanical fuel pump and added an electric fuel pump (marine pump with 5-7psi and more than enough gph. I also put in an oil pressue fuel pump switch with a 2psi cutoff). The problem still recurred.
2. Replaced the fuel/water separator
3. Double clamped all fuel line connections
4. Sealed the threads on all fittings (except those on the fuel tank fitting and pickup tube which I'll seal this week)
5. Checked the tank vent line - it was clear
6. Checked the fuel tank pickup screen - it was clean
7. Checked the screen on the carb - it was clean
8. Checked the anti-siphon valve - turns out there isn't one so that isn't the issue
9. Drained fuel to check for water - no water seen
10. Checked for water in fuel/water seperator - no water seen.
11. Checked every fitting and fuel line for obstructions - no obstructions found.
12. Added blue Stabile - didn't help

Things I plan to do.

1. Seal the threads on the fuel tank fitting and pickup tube
2. Replace all fuel lines from tank to carb

My working theory at this point is that I'm drawing air somewhere along the way. I think it is a very small air leak. I now suspect it is a pin hole in the fuel line or a leaking thread at the fuel tank fitting or where the pickup tube threads into the fuel tank fitting. The air is getting caught up somewhere (fuel/water separator?) and eventually a large enough bubble forms that works its way to the carb. With the greater demand for fuel under higher RPMs the air bubble increases in size more quickly which explains why the issue occurs when it does. It has never occurred at idle or low RPMs. On the one occassion the boat would not restart, I pulled the fuel line coming from the fuel pump to the carb (this was after I replaced the mechanical pump but before I added the electric pump). There was very little fuel in it.

I don't think it is vapor lock because it happens at higher RPM. It has never occurred after being underway and stopping and sitting for a bit. Nevertheless, as mentioned above, I did add blue stabile with no improvement. It also occurred with non-ethanol fuel. Finally, I've taken to running the blower at idle and when we stop to swim or just hangout on the water. This too has failed to alleviate the problem.

I'm open to any suggestions at this point. Thanks in advance for the help.

Shannon

[mysledblows]

I had a similar issue and found the o ring on the fule filter was pinched. This would allow it to suck air rather than fuel at high rpm. Below 3 grand I was fine. Above it wouldn't really run at all.

[OLDSCHOOL85]

I think your heading in the right direction. I would go ahead and replace your fuel line all together. Its an inexpensive and fairly easy swap. Also if you have an exhaust leak, it may still vapor lock at higher RPM's, so check for that.

[svahle]

mysledblows - I'll double check the filter o-ring. But I did replace the filter and the problem persisted before and after.

OLDSCHOOL85 - I probably should have replaced the fuel lines sooner in this process. I guess I just didn't think they were a likely culprit as they are only a couple years old and there isn't really anything that rubs against them or would cause wear and tear. I'll get those replaced this week and also check for an exhaust leak.

Thanks for the suggestions.

Shannon

[OUI]

Check your breather tube, if it's clogged it will starve the engine at high RPM. To check it, unscrew the filler cap and go for a spin, if it doesn't die the breather is the problem.

[rludtke]

You didn't say that you overhauled the carburetor, so try this theory on for size...

If a foreign object resided in the float chamber inlet area, it could flow into the needle seat when fuel is flowing, and create an obstruction. After the engine quits, and fuel stops flowing, the obstruction could float out, allowing you to restart. In my case, the obstruction would hold the needle open, and cause flooding, but I can imagine if the object was large enough, it could block or partially block fuel as well. If the engine consumed more fuel than the carb can deliver, the engine will quit.

The object could get passed the carb inlet screen, if the screen is not fully attached. This happened to me. The screen existed, and was not dirty, but it took me several seasons of intermittent carb issues to realize the screen was no longer fully crimped into place, and would flap open allowing crud to pass. I just added an in-line filter in the carb supply line to solve this.

I also like the blocked fuel vent theory. I have seen this before as well. If the problem goes away when the fuel filler cap is loose, then the tank vent is plugged.

Just for the record, vapor lock is the result of fuel heating after shut down. During operation, a constant stream of cold fuel will prevent the condition from occurring.

I would overhaul the carb to ensure that the critical parts are new and the insides are clean, and make sure the inlet screen hasn't separated, and then try it.

I don't think your air bubble theory is the cause, as the float chambers are vented. If a slug of air came in, it wouldn't matter much, air is compressible, and it is lighter than the fuel, and would leave out the vent. This might reduce the float level for a very brief period of time, but fuel flow would return, and the engine might not even notice.

Now for a totally different theory:
Maybe it is an ignition problem. As engine RPMs increases, so do the combustion chamber pressures. As the pressure increases, so does the resistance, making it more difficult for the spark to jump the spark plug gap. This is why spark plug testers test spark plugs under pressure. My theory is that your ignition system may be weak. How long has it been since the last tune up?

Cheers,

[jet]

I second that..rebuild the carb. I dont think Its a air leak. Jet

[edgewater1]

unless u can rebuild it yourself, just replace it. u can get a holley carb for 250-300 it would cost at lest 150 to pay someone to rebuild.

[fastab]

I have not read all of the suggestions, however this is a common problem on the older comps. The fuel tank vent was located at the back of the boat under the gunnel molding, in corners and when passengers shift weight it can go under the water and let water in the fuel tank. The water fuel filter will stop most of this but when it gets full water will go into the carb. Water does not flow like gasoline and can plug the jets or restrict the jets when fuel is flowing thru them. It will be intermitant, as soon as you shut the motor off and there is no demand the water will settle to the boat (heavier than gas)
If your fuel vent is located where it maybe able to get water in from weight shifting in the boat or backsplash when you slow down you should have it relocated to a point where this won't happen. You may also have to take the carb apart to clean it depending on how much crap it got in it. If you don't fix the vent it will continue to get water into the gas.

[svahle]

Thanks for the added replies. I have already tried removing the fill cap but the problem persisted. A little history on the boat. It was a complete restoration beginning in 2006 (many of you followed the rebuild thread in this forum by knoxsupra). As I understand it, the carb was rebuilt then. But I'll check into it as the suggetions in that regard make some sense to me. The electronic ignition was also added during the restore. So, these parts are fairly new. Nevertheless, I appreciate that sometimes even newer parts fail.

On one occassion, after it died and while still utilizing the mechanical fuel pump, I pulled the fuel line off the pump that runs up to the carb. I cranked it over and the pump wasn't putting out fuel. Using a mighty vac I re-primed the fuel lines. It then started and ran fine. Also, after the motor dies, fuel will not come out of the nozzles in the carb when moving the throttle. As if the accelerator pump isn't getting fuel. These are other reasons why I believe it is a fuel and not spark problem. But, at this point, I'll start looking at the ignition side also.

Thanks again for the thoughts. If I get the gremlin trapped I'll be sure and let everyone know what the problem was.

Shannon

[rludtke]

Well Shannon, you convinced me that it is your pump. These mechanical fuel pumps will normally prime themselves, even if the hose are brand new empty. If fuel wasn't present and it wouldn't prime, then I think you've found the culprit.

I can't explain why it is intermittant, or only a high rpm problem, but the diaghram probably has a hole or something. A scarier root cause thory is that the cam eccentric for the pump has lost it shape, but I suspect that this is unlikey. Any chance you could borrow a pump from a friend and mount it for a test?

[svahle]

rludtke - I initially targeted the fuel pump as the source of the issue also. So, I replaced the mechanical fuel pump and the problem persisted. I have now bypassed the mechanical fuel pump and am using an electric fuel pump. The problem still pops up from time to time. But it seems to be a little less frequent (maybe that is just wishful thinking on my part). I went to an electric fuel pump thinking there might be an issue with the eccentric. This motor has a two piece eccentric which appears to be in good shape when inspected through the slot for the fuel pump arm. My thinking was that the tab that inserts into the cam gear somehow failed thereby allowing the eccentric's inner hub to randomly free wheel on the end of the cam rather than spin with it. But now that the problem still exists from time to time with the electric fuel pump, I've excluded that as being the culprit also.

I figure fuel line is cheap compared to all the parts I've already replaced. So, I'm gonna go ahead and replace the fuel line from tank to carb, finish double clamping each connection, and finish sealing the threads on each fitting. I need to look more closely at the pickup tube in the fuel tank and how it attaches to the elbow fitting in the top of the tank. That could be another place to draw air potentially.

Here's another question/theory - If there is an air leak sufficient to cause the motor to die, might it be a big enough leak to cause the fuel lines to lose prime and prohibit the fuel pump from being able to re-prime the system on its own? Maybe it isn't an air bubble causing the motor to die. Maybe it is drawing enough air that the fuel pump can't create and maintain enough vacuum in the fuel system from tank to pump (i.e. losing prime)?

Obviously I'm still scratching my head at this one as is my step-father who has been a mechanic for 35+ years. But, sooner or later I'll get it figured out. It just takes time and money, right?!?

[rludtke]

[QUOTE=svahle;41631]

Here's another question/theory - If there is an air leak sufficient to cause the motor to die, might it be a big enough leak to cause the fuel lines to lose prime and prohibit the fuel pump from being able to re-prime the system on its own? Maybe it isn't an air bubble causing the motor to die. Maybe it is drawing enough air that the fuel pump can't create and maintain enough vacuum in the fuel system from tank to pump (i.e. losing prime)? [QUOTE]

Well Svahle,

I like your theory, it makes sense, but with one problem. I think a leak that size would also drip fuel, enough that you should see the puddle. You certainly have this problem thoroughly bracketed. I am surprised you haven't had better results yet.

Keep at it, and good luck.

[brack]

having fuel issues myself , ( a lil water issue ) I check my fuel filter cannister and noticed (1) i forgot to put in the filter and (2) the cannister was half full of water .

i installed a new filter , but it would not start up , i bypassed the filter cannister and it ran great.........i removed the filter out of the cannister and then put an inline filter .......BAM.....fired right up and im headed to the lake to test it.......hopefully its fixed and i had a problem with the older cannister type filter.....we will see

[brack]

Disclaimer ( not trying to HiJack the thread , just hoping we can figure our probs out )

well , took her out today , ran great for the 1st ten minutes then she fell flat on her face .....let sit for ten minutes and she starts......did this for several times...... frustrated i took back to the dock and loaded her up.....

check fuel filter , all OK.... check tank vent OK.......started her up on a hose and she purrs like a kitten.......getting frustrating with it.....She ran fine on the first tank of gas , then on the thried trip out on the next tank.....these issues started

[brack]

OK....just got back from the boat ramp.......thought i would try her today again BUT without the doghouse ( thinking maybe the engine is getting tooo hot ) same results , ran 10 minites then just sputtered and quit . temp about 170-180 . sat for 5-6 minutes and the process started over . I did noticed in my clear fuel filter that my gas was bubbling......gonna try a new thermastat and electric Fuel pump....Look like we are are trying the same things , maybe one of us will hit it on the head soon

[fastab]

OK....just got back from the boat ramp.......thought i would try her today again BUT without the doghouse ( thinking maybe the engine is getting tooo hot ) same results , ran 10 minites then just sputtered and quit . temp about 170-180 . sat for 5-6 minutes and the process started over . I did noticed in my clear fuel filter that my gas was bubbling......gonna try a new thermastat and electric Fuel pump....Look like we are are trying the same things , maybe one of us will hit it on the head soon

If you had a lot of water in the seperator you probably have water in the lcarb, it will settle to the bottom when the engine is not running. (water is heavier than fuel) Water does not like to flow thru the jets and displaces fuel so it will cause misses and can cause the engine to die if there is enough.
if there is dirt in the carb it can do the same thing. I have seen the filter housing rust and this will constantly try and get into the carb.

On the older comps late 80-early 90's the fuel vent was at the back of the boat under the gunnel molding and this can be the source of the water problem. It can get in when you slow down and stop or when the weight in the boat shifts to the side that the vent is on and it takes a gulp of water, which will add up over time. If you find water in the tank you should relocate the fuel vent.

[fastab]

rludtke - I initially targeted the fuel pump as the source of the issue also. So, I replaced the mechanical fuel pump and the problem persisted. I have now bypassed the mechanical fuel pump and am using an electric fuel pump. The problem still pops up from time to time. But it seems to be a little less frequent (maybe that is just wishful thinking on my part). I went to an electric fuel pump thinking there might be an issue with the eccentric. This motor has a two piece eccentric which appears to be in good shape when inspected through the slot for the fuel pump arm. My thinking was that the tab that inserts into the cam gear somehow failed thereby allowing the eccentric's inner hub to randomly free wheel on the end of the cam rather than spin with it. But now that the problem still exists from time to time with the electric fuel pump, I've excluded that as being the culprit also.

I figure fuel line is cheap compared to all the parts I've already replaced. So, I'm gonna go ahead and replace the fuel line from tank to carb, finish double clamping each connection, and finish sealing the threads on each fitting. I need to look more closely at the pickup tube in the fuel tank and how it attaches to the elbow fitting in the top of the tank. That could be another place to draw air potentially.

Here's another question/theory - If there is an air leak sufficient to cause the motor to die, might it be a big enough leak to cause the fuel lines to lose prime and prohibit the fuel pump from being able to re-prime the system on its own? Maybe it isn't an air bubble causing the motor to die. Maybe it is drawing enough air that the fuel pump can't create and maintain enough vacuum in the fuel system from tank to pump (i.e. losing prime)?

Obviously I'm still scratching my head at this one as is my step-father who has been a mechanic for 35+ years. But, sooner or later I'll get it figured out. It just takes time and money, right?!?

Pull your fuel sender out if you have good access to it and try and look around in the tank maybe somebody dumped a rag or something in there and it is floating around and occassionally plugs the pickup tube under strain, another thing is the pickup tube down to the bottom, and is it cut on an angle, I have seen on some other brand of boats that the pickup tube will actually suck the bottom of the tank up under high load and it will run out of fuel. If it is not cut on an angle try and cut the pickup on a little bit of an angle so that it can't suck the tank up.

[svahle]

I'm at my wits end on this problem. In addition to all the things mentioned above, I have now replaced ALL the fuel lines and sealed every threaded fitting from the tank pick up to all the way to the carb. The pickup tube screen is clean and cut at an angle. Although I have checked the tank vent tube, I even tried running the boat with the fuel filler cap removed and the problem still occurs. My tank vent tube is next to the rear cleat on the port side so it never gets at or near water level (and I haven't added ballast yet either).

Basically, I can run around all day without a problem if I stay below around 2700 RPMS. We surfed and wakeboarded all morning Saturday without an issue. But when I threw on the slalom ski and the boat was opened up to about 33 mph (roughly 4000 RPM), the motor died after about 5 minutes at that speed/RPM. After pumping the throttle and cranking it a bit, I was able to get it restarted. It would purr like a kitten up to about 2700 - 3000 RPMs and then would die again. As long as keep the RPMs below this threshold, it runs flawlessly.

I don't know much about carberators, but I'm starting to think that could be the issue. What strikes me as strange is how perfectly the boat runs until the gremlin pops up. On only a few occasions I have been able to run the boat at nearly wide open for 15-20 consecutive minutes with no issues. But, usually, I can recreate the problem by running the boat for 5-10 minutes at near wide open throttle. Until the engine dies, it never feels weak, never bogs down, has ample power, etc. I'm running 3/8" fuel line from tank to carb. That should be sufficient, right?

I'm going to contact a boat mechanic that I understand to be reputable and a good diagnostician. Hopefully he can get the boat out on the water soon and get the issue figured out. In the mean time, I'm certainly open for further suggestions from those on this forum. I have very much appreciated all the help thus far.

Shannon

[wotan2525]

Just noticed this thread... how about air flow? Have you tried running with the dog-house off to see if it's possible that your intake lines are rotten and the engine isn't getting enough o2 at higher RPMs?

[rludtke]

Another possibility is the float level. If the float level is too low, you may be draining the float chamber at higher power settings faster than the fuel can refill. Raising either the primary or secondary (or both) float levels might solve this.

[svahle]

rludtke - Funny you should mention that, I did some more research yesterday which suggested the float level being too low could potentially cause this problem. I'm an absolute beginner when it comes to carburetors. But, I have the manual for it and surely I can figure it out. I should have time tomorrow night to give it a shot. Thanks again for all your help and suggestions.

Unfortunately, the boat mechanic I was referred to is very back up. He has about 50-60 boats in line waiting for attention. So, I'll continue to try and address the issue with the help of this forum and other resources.

Shannon

[brack]

SVAHLE... ,

Hopefully one of us will find the problem soon . im in the same boat ( no pun intended ) as you . Boat having same syptoms and issues . Thought i narrowed it down to a bad thermastat , but still dropped dead on its face this past sunday ....

Maybe before summers over we will find the lil Gremlin.....good luck and ill keep posting what i try.....think im gonna try to adjust float levels ( as mentioned above )....who knows at this point.....sorta scratching my head because it ran great the first two trips out on the Lake...

[rludtke]

rludtke - Funny you should mention that, I did some more research yesterday which suggested the float level being too low could potentially cause this problem. I'm an absolute beginner when it comes to carburetors. But, I have the manual for it and surely I can figure it out. I should have time tomorrow night to give it a shot. Thanks again for all your help and suggestions.

Unfortunately, the boat mechanic I was referred to is very back up. He has about 50-60 boats in line waiting for attention. So, I'll continue to try and address the issue with the help of this forum and other resources.

Shannon

Hi Shannon,

Float adjustment is actually very easy. Holley.com has tons of technical publications, including "Guidlines for adjusting float level" http://www.holley.com/data/TechService/Technical/Adjusting%20Your%20Carburetor.pdf
(Ref: http://www.holley.com/TechService/Library.asp)

This exploded view may help:http://www.holley.com/data/TechService/Technical/4150-4160%20Exploded%20View.pdf)

Adjustment is made by bending the float arm small amounts. The instructions provide some target dimensions.

I have also fine tuned my adjustment on the lake. If a stumble exists, I increase the float level until the stumble disapears under hard acceleration load.

[svahle]

Here is a little update. I pulled the bowls off the carb last night. Both are very clean. The rear float may be a little low, so I'll raise it a bit tonight (although I don't think this is the problem given its current setting). Although I have limited experience with carb adjustments, everything else looked fine to me.

The last time the boat stalled I was again trying to ski and my girlfriend was driving. She restarted the boat and came around to pick me up. Last night she mentioned that it turned over a little slower than usual on restart. So that caused me to again consider the electrical side of things. After a little research last night, I found a few instances where a weak alternator caused problems similar to mine. The theory being that the alternator is putting out just enough juice to keep the battery charged enough to start the boat. But after running the boat a while at high RPMs the alternator can't keep up, the battery charge gets low, and the ignition system simply can't draw enough volts to function. Or as better explained earlier by rludtke - "As engine RPMs increases, so do the combustion chamber pressures. As the pressure increases, so does the resistance, making it more difficult for the spark to jump the spark plug gap. This is why spark plug testers test spark plugs under pressure. My theory is that your ignition system may be weak." So, I pulled the alternator off last night and had it tested this morning. Sure enough, the output is low. Luckily, I was able to find a new one locally (yes it is a marine alternator). I'll slap it on tonight. Of course a bad coil can cause similar issues, but based on my research, a bad coil usually gets too hot and needs to cool before the motor will restart. Certainly there are other parts of the ignition side that can cause similar problems. But, I've at least tracked down a "bad" part and will start there.

I'm hopeful that the alternator will cure the issue. But, at the same time, I'm perplexed by some of my prior findings such as the fuel pump failing to reprime and lack of fuel in the accelerator pump after stalling on occasion. These problems would be unrelated. I'm a realist and find it a bit to coincidental that there are both fuel and ignition issues. But, I suppose it's possible.

If I can get away from the office a little early I should have time to put the bowls back on the carb, install the new alternator and head to the lake for a test run. If so, I'll certainly report back my results. If the alternator does fix the issue I'll be a little frustrated that I wasted time and money chasing the wrong rabbit for the last several weeks. At the same time, I'll be relieved that the hunt is over, the Gremlin is deservingly dead, and that I can again ski for more than a few minutes at a time. Wish me luck!

EDIT: rludtke, thanks for the links and info on settle the float levels.

[svahle]

And the saga continues.........

I skipped out of work a little early yesterday afternoon to put on the new alternator and raise the secondary float a little. I then took the boat to the lake for a test run. Things were going great and just about the time I was convinced I had the problem fixed, it stalled. I was frustrated to say the least. I took some extra fuel line and a 5 gallon gas can with me. I ran the extra fuel line from the gas can directly to the fuel pump. It ran perfect. That also gave me the chance to see just how quickly this boat will burn through 4 gallons of gas (about 10 minutes at wide open throttle). I then ran off the boats fuel tank again and the problem recurred. At this point I'm running out of daylight and headed back to the boat ramp.

Athough I had looked in the tank twice before and checked the screen on the pickup tube, when I got back to the house, I decided to syphon all the fuel from the tank. I poured the syphoned gas through a funnel with a screen and found some debris. What I found looks like teflon plummer's tape, but its black. I suppose it could be electrical tape that has broken down over time being soak in fuel. There were three or four pieces about 3 inches long or so. I pulled all the fuel I could from the tank. But, I can still see a few very small black pieces of debris in the tank. Hopefully, I was able to remove all the larger, more problematic pieces. I'll be on the water this weekend, so we'll see if this has fixed the problem.

If the problem continues, here are my short term ideas to get me through until winter when I can pull the tank and give it a proper cleaning. I've already began thinking about adding an integrated ballast system that would require rebuilding the rear seat. When I tear into it I could remove and clean out the tank.

(1) I'm wondering if I should remove the screen on the pickup tube and put some sort of an inline screen on the fuel line (between the tank and fuel/water seperator) that is more easily accessible. Then, as the problem occurs I can clean out the inline screen without having to mess with pulling the pickup tube.

(2) I could fabricate some sort of a wire mesh cage around the end of the pickup tube. It would need to be small enough to fit through the hole in the tank for the pick up tube fitting, but large enough that it couldn't be completely obscured by the debris in the tank.

Anyone have any other thoughts or ideas for a short term fix? Thanks.

Shannon

[fastab]

You had your float bowls off and said that they were clean, so the debri is not making it to the bowls, It may be stopped at the water/fuel filter or it may be something big blocking it in the tank.

Do you still have the anti-siphon valve in the tank this sometimes can malfunction and block flow. Also on the pickup is the bottom cut on an angle if not how close to the bottom of the tank does it get. I have seen on some boats the pickup actually suck the bottom of the tank off cutting off fuel flow.

Small pieces would get trapped in a filter, you could intsall a second filter or a sediment trap style that you could see and drain/clean.

[svahle]

There isn't an anit-siphon valve, just a brass 90 degree elbow. The pickup tube is cut at an angle and has a screen on the end. That is where I believe the obstruction is occuring. I've checked the fuel/water separator and don't see any debris in it (at least as far as I can see and I haven't cut it open). This is also a new fuel/water separator as it was replaced early on in this process, but the problem persisted.


You had your float bowls off and said that they were clean, so the debri is not making it to the bowls, It may be stopped at the water/fuel filter or it may be something big blocking it in the tank.

Do you still have the anti-siphon valve in the tank this sometimes can malfunction and block flow. Also on the pickup is the bottom cut on an angle if not how close to the bottom of the tank does it get. I have seen on some boats the pickup actually suck the bottom of the tank off cutting off fuel flow.

Small pieces would get trapped in a filter, you could intsall a second filter or a sediment trap style that you could see and drain/clean.

[wotan2525]

How about one of these? http://www.amazon.com/Moeller-Universal-Inline-Glass-Filter/dp/B000MT94OM

That could cheaply/easily tell you if the problem is in the tank or not, right?

[svahle]

I was searching online and came across that same filter. I acquired a little dentist mirror today and I'll try and use it to look around in the tank to see if there is much more debris in there. If it acts up again this weekend I may pick up one of those filters. It would have to mounted in a safe location to keep the glass from breaking and dumping fuel in the bilge! I'd rather find a plastic one of some sort. I'll look more if it comes to that. But, I do appreciate the help.



How about one of these? http://www.amazon.com/Moeller-Universal-Inline-Glass-Filter/dp/B000MT94OM

That could cheaply/easily tell you if the problem is in the tank or not, right?

[fastab]

There isn't an anit-siphon valve, just a brass 90 degree elbow. The pickup tube is cut at an angle and has a screen on the end. That is where I believe the obstruction is occuring. I've checked the fuel/water separator and don't see any debris in it (at least as far as I can see and I haven't cut it open). This is also a new fuel/water separator as it was replaced early on in this process, but the problem persisted.

The anti siphon valve would be in the barb fitting off of the 90 on the pickup, it is simply a ball bearing a spring and a retainer. A lot of guys take them out or replace the fitting with a standard one so if this is not there then you are ok.

How big is the mesh on the pickup, if it is to fine it could send air up the tube, most pickups on older boats (with carbs) are straight thru no filter at the tank. You need a large obstruction to case it not to pump fuel.

[svahle]

Good news and bad news.....

The good news is that I have a confirmed diagnosis. The boat stalled twice today. Both times I pulled the pickup tube from the tank and the screen was clogged with more of the black debris I found in the gas I siphoned out last Wednesday. After cleaning out the screen, the boat ran perfect.

Now for the bad news. I will have to give the tank a thorough cleaning which may require pulling it out over the winter. One of the strips of black debris had white lettering on it. I'm assuming there is a hose that connects the tank to the fill nozzle. My suspicion is that the hose is breaking down and the lining of the hose is shedding into the tank. Does anyone know if the hose can be replaced without removing the tank? If I can eliminate the source, maybe with a little more time I'll eventually eliminate all the debris in the tank.

At least I now know the problem and can take the needed steps to cure it. I appreciate all the input from this forum and the help in trying to track down my gremlin.

Shannon

[rludtke]

Hi Shannon,

What can I say but: old boats, what do you do with them. At least you know the root cause. Thats always better than not knowing.

The fill nozzlemouts to the boat with a big nut (I think). I haven't been in their yet, but I think you can reach in behind the back seat (seat and rear close out panel removed obviously). I presume the hose clamps to the filler and the tank, and if the clamps can be loosend, and the filler rmoved out the top, you could probably replace the hose in the boat.

Some of the guys on this BB have separated the top deck from the hull to do the stringers, so they could probably confirm this, but I think the hose can be replaced in-situ.

[sybrmike]

Can't say for sure on an 86 Sunsport, but the fill hose on my 89 Saltare was hose clamped at both ends to the fill and fuel tank inlet nozzles and able to remove it before pulling the tank.

Don't know if you'll need to pull the ski locker or rear bench or both to get access, but shouldn't have to pull the tank (but if you're that far, it wouldn't be hard to pull it if you have to). The old hose is probably stiff from age, but you could cut it in half and remove the pieces of the old hose. New hose should be more pliable for installation.

[svahle]

sybrmike - Thanks for the information. My ski locker is integrated into the top cap so I can't remove it. Hopefully I'll have a little time this week to survey the matter and see how involved the process will be.

[87SunSportMikeyD]

svahle I have heard stories before of people's gas lines disintegrating from the inside. Before you pull your tank you may want to remove one end of the line from an easy-to-access spot and check the integrity of the inside of the tube.

[svahle]

On my boat on the starboard end of the ski locker is a removable vent plate. Once removed, I had access to the tank fill hose. It is a tight fit and takes some patience, but I was eventually able to remove and inspect the fill hose. It was in fine shape and appears to have been replaced not too long ago. So, I've eliminated it as a source of the material clogging the screen on the pickup tube. I also need to inspect the vent hose, but I feel it is a less likely culprit.

At this point, my suspicion is that the debris (which appears to be pieces of a failing rubber hose) came from a gas station or marina fuel pump. My plan is to proceed with running the boat and cleaning out the tank screen as problems arise. If this takes care of the problem before winter, great. If not, I'll plan to pull and flush the tank this winter.

[brack]

Finally got around to messing with my Rider today.....took her out with today , disconnected my main tank , connected the fuel pump to an Aux 6 gallon tank and WOW..... she ran like she got poked in the Buttocks!!!!...looks like im gonna be pulling my tank AGAIN......

[svahle]

Saturday I ran about 2 full tanks of fuel through my boat. It only stalled twice and when I removed the screen on the pickup tube I found more of the black debris. After cleaning out the screen it ran great. So, I'm certain I've found the problem and it seems to be improving. I think I'm slowly getting this issue behind me.