Help with Fuel Issue

[chrisk]

Need some of your guys' expert advice on a fuel delivery issue.

Yesterday, the motor started to cut out more and more like it was running out of gas until it finally just wouldn't start anymore. Plenty of gas in it. My boat is set up gas tank, fuel line, some kind of filter, fuel line, fuel pump, fuel line, carb. I took the fuel line off of the filter that leads to the fuel pump and no gas came out, completely dry. I force fed some gas into that line, put it back on the filter and now the boat will run. However, if I'm planed out and I take a hard corner the fuel cuts out again. Occasionally it will cut out when I'm in a straight line but I just ran it about 30 miles and still made it home.

Just looking for advice. Water in the fuel? Bad fuel pump?

[svahle]

If it were water in the fuel I don't think it would explain the bone dry fuel line between the filter and fuel pump. I suppose it could have syphoned back into the tank but that assumes the tank pick up tube is lower than the fuel line and that you do not have a check valve/ball between the tank and fuel filter. I would check three things. First, I would pull the pick up tube out of the tank and see if there is any debris plugging up the screen on the end of the pick up tube. I had a similar problem and finally found rubber pieces from the inside of a fuel line in my tank. My theory is ethanol fuel caused break down of a fuel line at one of the gas pumps used to fill the boat. The pieces would eventually plug up the screen on the pickup tube and starve the engine of fuel.

I'd also check to see if there is a check ball in any of the fittings between the tank and the fuel filter that might be hanging up and preventing the flow of fuel. In addition to the above, I'd go ahead and replace the fuel filters. I suppose the fuel line could also be separating internally and occluding the flow of fuel especially if the fuel lines are older and you have run fuel with higher ethanol content. You might also make sure all the connections are tight. I have heard of connections being just loose enough to draw air under vacuum, but not loose enough to leak.

What I did to trouble shoot my problem was take a couple five gallon gas cans and some extra fuel line with me out on the boat. You can go about it from either end of the fuel system, but I started at the fuel pump and worked my way back to the tank. Run the extra fuel line from the drawing side of the fuel pump directly to the gas can. If it runs good, then run the extra fuel line to the drawing side of the fuel filter and so on until you have isolated the problem.

[chrisk]

Thank you for the detailed write up!

Saturday we did run from a spare gas can directly to the fuel pump and it ran fine so it's not the pump. Haven't been able to continue working backwards as you've suggested because I didn't have extra fuel line or time...

In suspicion of the problem being water in the gas sloshing around I put two bottles of Heat through it. It seems to be making the problem happen less often. So I'm really hoping this is all that was wrong with it. Going to run it again tomorrow and see where I'm at.

[svahle]

One thing that may be fairly easy to check while on the water is the pickup tube in the tank. If yours is like mine, you can access it through a door in the bottom of the ski locker. Just pull the hose off and unscrew the elbow. Once I figured out my issue, when it would die, I would immediately run back and pull the pick up tube and clean off the rubber pieces. All you should need for tools is a screw driver for the hose clamp. So, if yours does die again, check that and you might find the problem. Good luck and I hope you get this sorted in short order. It can be frustrating chasing a fuel problem, but probably not as frustrating as chasing a spark problem (at least for me any way).

[chrisk]

Not an option for me, my pick up comes in from the top of the tank and accessing it requires sliding the tank out... after I remove the rear seat...

[chrisk]

Fuel issue is still acting up... Every once in a while it will cutout, otherwise the boat runs great. I've put 25 gallons of new gas in it since this started happening and I've probably used 20 gallons of that, as well as two bottles of Heat. Every once in a while the problem will happen when driving in a straight line but it seems that I can almost 'make' the problem happen when I take a sharp turn at speed.

Also, I drained the fuel filter and a few particles came out along with slightly suspicious looking gas. Any ideas?

[wotan2525]

Someone in here struggled with one of the hoses breaking down (maybe the filler hose?) and sending debris into his tank. It was almost the same as the problem you are describing. Do you have a fuel/water filter? At this point I would syphon out ALL of the gas still in the tank. I know you can't see what's going on, but all of your descriptions point to there being some kind of debris or particles in there. I'd probably try to suck out through the filler tube and flush it a few times. Might have to pull the tank to make this happen. It's a pain but not as big of a pain as being stuck.

[svahle]

Someone in here struggled with one of the hoses breaking down (maybe the filler hose?) and sending debris into his tank.

That was me!

Chrisk - I too think it may be a good idea to syphon the tank through the filler hose since you can not easily access the pick up tube or sending unit. Because of the access door in my ski locker, I could get to the top of my tank and syphoned through the hole for the sending unit. With a flashlight I was able to see down into the tank a little and saw other debris in there. I syphoned the fuel through a funnel with a screen filter so I could see if there was debris coming out with the gas. You might try this just to see if there is any debris in the tank. Yes you may have to eventually pull the tank to clean it out thoroughly, but maybe this would help you determine if that is the problem.

Does this happen most often at higher RPMs? My problem was most frequent at WOT since these V8s can suck fuel at an alarming rate at WOT and pull more debris into the pick up tube screen from the tank.

I suppose you could also cut a hole in the bottom of the ski locker and put in an access door. This would give you access to pull the pickup tube next time the problem occurs and see if the pick up tube screen is clogged up.

[chrisk]

Thanks for the suggestions guys. Might try all or a combination of them.

Svahle, what kind of filter did you use in your funnel when you siphoned out the gas?

[svahle]

Thanks for the suggestions guys. Might try all or a combination of them.

Svahle, what kind of filter did you use in your funnel when you siphoned out the gas?

I have a funnel I probably bought at Walmart that has a screen where the cone of the funnel meets the neck. If you can't find one of those, in the kitchen gadget aisle of Walmart they have screens that fit in a sink drain. You could just drop that in any funnel. I use those to strain old paint for furniture refurbishing projects my wife and I take on.

[docdrs]

Sounds like you have already narrowed it down to between your fuel tank and pump........if its suction draw and there is a one way valve thats sticking it is most likely the culprit. replace the line if thats the problem plain and simple

[chrisk]

Thanks again guys.

It's so weird how it's so intermittent, I ran the boat for about 20 miles last night with hard accelerating, decelerating, and turning mixed in and had zero hiccups.

[svahle]

Here are a few more thoughts if the above ideas do not work.

I assume you have a mechanical fuel pump. But, if your boat has been changed over to an electric fuel pump, you might run the wires and check for a loose connection. That could cause an intermittent problem.

I suppose it is possible that your fuel tank vent is clogged and a vacuum is being created in the tank as fuel is drawn out by the fuel pump. If you can't get to the vent hose easily, you might try and diagnose this problem by opening your filler cap the next time this gremlin shows his ugly mug. As you open it, listen for air rushing in and try and feel if there seems to be suction. If that is the issue, it should run fine with the filler cap removed.

If you have a mechanical fuel pump, I have heard of issues with the pump arm and fuel pump eccentric on the crank shaft. I really doubt this would be your problem so I think this would be the last place to check.

I still think this is either an issue with a sticking one way valve/check ball or debris in the tank. That is where I would focus my efforts at this point. Best of luck and keep us posted on your efforts.

[chrisk]

Well this past weekend was my annual 200 mile boat trip... and of course this problem decided to show itself. The boat ran absolutely great 100 miles up the Mississippi from St. Louis to Quincy, IL. Then it ran about 25 miles back before it started sputtering and eventually wouldn't start. After towing it another 25 miles to the marina we were spending the night at I removed the fuel pump and took it in to the shop they had there. We were able to hook the pump up to a spare gas tank, manually pump the arm, and fuel blasted through the pump. We put the pump back in the boat and tried cranking it over but only got a few sputters of gas to come out. So, I believe there's something going on in the fuel lines from the gas tank. I'll be pulling the back seat out hopefully today so that I can investigate.

[chrisk]

Feel pretty foolish but I fixed the boat so I'm okay with it. I took the back seat out to start to remove it to diagnose the problem. As I was looking under the ski locker bin at the fuel pick up line I noticed there was a vent above the line in the ski locker. I took out three screws and removed the vent. Wiggled the fuel line on the petcock a little bit and immediately noticed a crack in the side of the line where the hose clamp had worn through over time, allowing air into the fuel line. Removed the line, cut back about two inches, put it back on, and the boat runs like a dream. Problem solved, lol. Thanks for the help guys.

[svahle]

Good to hear you found the issue and thanks for posting the solution.

[docdrs]

^^^^^^^ ditto