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.

1. Big hose for fuel Filler
2. Line for fuel breather/vent
3. 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.