Help me isolate a fuel problem, a checklist if you will

[haugy]

1990 Mariah, 351w, Holley carb.

This year it's had a carb rebuild, new spark plugs, and new fuel filter. Boat ran fine for a weekend, like a champ. No problems at all. The following weekend the boat started having random problems. 1/4 mile from the ramp she would sputter down when cruising, if I backed off I might keep her running, but mostly would die. I thought the carb had become dialed out or something, after fruitlessly working on the carb and the settings ending up where I started, I got the boat running, and ran all day with no more problems.

Yesterday, I get it at the ramp, it fires up, and then sputters dead. Takes everything I've got to get it to start, wide open throttle at many times. After floating her to the dock so I could work on it. I came down to this.

I could get it to start everytime, if I held the choke closed, but then I could barely keep it running.

So, here's my checklist of things I'll be looking at.

1) Checking to make sure the fuel pump is delivering a lot of fuel.
2) Checking the fuel filter
3) Checking the fuel pickup in the tank

This is a fuel related problem. The choke getting it to fire everytime is a dead giveaway. The carb doesn't have float adjustments, and it ran fine before. Which leads me to believe something became jammed or failed recently.

Anything else I'm forgetting?

[mapleleaf]

Sounds like it could a fuel pump issue or a clog some where. I had the same issue this year, turns out there was a filter screen installedwhere the fuel line enters the carb.Totally clogged, cleaned it and was back running.
Wouldn't hurt to pull your new fuel filter and check it for sediment.......
I also ran my tank right down without knowing (fuel gauge issue) I'd try all this with a full tank

[haugy]

Yeah, I cleaned the screen when I did the rebuild, but I'll be checking that when I pull the line to test the pump. I'll be pulling the filter as well. When all the hoses are disconnected I'll be sending air through the lines to check for clogs.

Fuel tank was full, just topped it off.

[88MariahATX]

I would check for water in fuel. I had similar sounding issues and that was the culpret. Check and see if the vent to the tank got stopped up also.

[haugy]

Check and see if the vent to the tank got stopped up also.

Will do, thanks. I'll be checking for water in the fuel as well. Once I check all the lines, and the pump, I'll be running the boat on a 5 gallon gas can.

[jonyb]

You can use my boat whilest yours is broken. Not like I'll need it anytime soon.

[haugy]

You can use my boat whilest yours is broken. Not like I'll need it anytime soon.

I know that sucks man. But don't kid, I'll be up there faster than you can say WTF!!

[Okie Boarder]

Definitely sounds more like a new problem that could be fuel delivery or bad fuel related. Did you try running it in the driveway at home before you checked or changed anything only to get the same result?

[haugy]

Ran fine for weeks. Ran it almost out of gas. Filled up and started having problems, but the fuel looked clean. Did my checklist. Fuel delivery is not the problem. Pulled the filter and everything looked fine. It started, ran for a bit, hen died. Pulled the filter again and found water. So I'll be pumping 30 gallons of fuel out, and getting some new filters.

I normally carry spares, but got careless. I have spares of everything else, so I'll have a few now.

Hopefully that will fix it. I knew my baby wouldn't fail me, I'm to anal about her.

[brack]

......had the same problem.......turned out to be water in tank....she ran fine out of a gallon jug.......drained it and shes back.....good luck

[svahle]

I'm chasing a fuel problem also on my 86 Sunsport. I just bought it and had trouble on my first outing. After running all fuel lines, connections, tank vent, new fuel filter, new fuel pump, etc. I thought I had it fixed only to be towed back to the marina by a sailboat on outing number 2. I think I have it narrowed down to the fuel pump eccentric on the end of the cam shaft that actuates the arm on the fuel pump. In my case, the fuel pump simply doesn't pump when installed but will work just fine if actuated by hand. This can be an intermittent problem (if the eccentric is loose it can migrate fore and aft thus engaging the fuel pump arm at times. If it is worn it may be may be actuating the fuel pump arm but not a sufficient amount to sustain appropriate fuel flow especially when the demand increases as you give it more throttle). You can pull the fuel pump and look in where the arm enters the motor. You'll see the fuel pump eccentric (a flashlight and mirror will help). Try and see if it is worn such that it will not fully engage the fuel pump arm. Also, if it is loose the bolt holding it on may have backed out some. I believe there is also a pin and tab that hold it in place (depending on whether it has a 1 piece or 2 piece eccentric). If this is the problem and it's loose you'll need to remove the timing chain cover for the repair. A backed out bolt or pieces from a broken eccentric can cause havoc with the timing chain and gears). If it's solid and just worn, the easier fix is converting to an electric fuel pump (marine of course) and oil pump safety switch. Also, look at the wear on the fuel pump arm. They don't always wear in the center of the arm, but if the wear is on the edge closest to the bow this might also help confirm that the eccentric has migrated. Just thought I'd throw this out there. It's a rare issue but it can and does happen (you'll find more on this potential problem by searching some Ford truck and classic mustang forums). Good luck and please let us know if you track down the culprit.

[haugy]

Well CRAP!! I'm about as frustrated as it gets. I've got two of these motors, and I've rebuilt motors from scratch for years, but I can't figure out what's wrong with this one.

Still fuel related. Checked the fuel pump (which is mechanical not electrical) and she's pumping all over the place.
Drained all the fuel, put in Heet, put fresh fuel and a new fuel/water filter in. Still barely runs.

It will start if I prime it with fuel first, and fire up. Then runs fine for a few seconds then it will try and sputter out. Sometimes if I open it up to 2500rpm she'll hold it, for about 10 seconds before it will sputter out and die.

I'm not getting fuel somewhere. I checked the pickup at the tank, I'll be pulling the hose off the fuel filter going into it to make sure it's not jammed. I don't see how with the screen on the pickup. Then I'm going to pull the carb and rebuild it, again.

I'm also throwing a new fuel pump on just for shits and giggles.

WHAT AM I MISSING!?!?!?! I've never had a problem dialing a motor in, but this is driving me nuts. 4 years with flawless performance. She was called Old reliable on the water because mine would always run when my friends newer ones wouldn't. I can't let her reputation fade. LOL

[jonyb]

What about spark? Could it be related to that?

On a side note, Wakefest? Pretty sure I'm off work until September, but don't know how the back issues will impede on me coming down. May come down by myself if you guys would jump in my boat.

[haugy]

Thought about that, but when I choke the carb down manually, it fires right up everytime.

It's gotta be fuel related. I'm going to be checking spark and timing today just in case.


We'll see about wakefest. I'll give you a holler next week.

[riveredge]

Have you run the boat on a separate tank with a known good fuel line right to the pump? That would eliminate a collapsed line between the tank and engine... I've seen collapsed lines that were only a year old, caused by e10 fuel.

If you replaced the spark plugs, are all your plug wires in good shape on both ends? I know you said it starts right up if you choke the carb manually, so it's probably not spark related, but it's a thought anyway.

[svahle]

One more thought on this. I'm sure you've checked all the hoses and hose clamps. But, have you pulled the threaded fittings from the tank, fuel/water separator housing, fuel pump and carb and made sure the threads are sealed? Sure sounds like you're drawing air somewhere given that it'll fire after being primed. I can't remember if you mentioned checking the tank vent hose and anti-siphon valvue. If you haven't, I'd check those also.

When it dies you might start at the carb and pull the fuel lines one by one to see if there is fuel in the lines. If not, keep working your way back. If you come to a point where there is fuel in the lines it may tell you where along the way you're drawing air (if in fact that is the issue). For instance, if the line on the tank side of the fuel/water seperator has fuel in it, but the line coming out of the seperator doesn't, it's likely drawing air somewhere at the fuel separator. This isn't a fool proof plan, but it can be helpful.

Good luck.

[jonyb]

We'll see about wakefest. I'll give you a holler next week.

Don't know what kind of shape I'll be in, or what the boss will let me do, but I know I'm off until September, and she's working that weekend, so maybe we can work something out. I'd be very limited so I'd need a good crew, but you guys could leave your boat and ride with me, along with Brandon and his wife if he wanted to.

[haugy]

Alright, here's where I'm at. I found water in the fuel filter. So I drained all 32 gallons and put Heet in it, with fresh fuel. Still problems. Start to work on her Friday afternoon, and she starts up and idles fine. Ok, that's frustrating. I did nothing. So I think the Heet finally had some time to do it's work, and get into the lines.

I have one 21 micron filter, and have two 10 micron filters. So I put on the 10 micron to catch anything that comes through. So I load up and head out to dinner Friday night on the water. I make it about 5 miles, and she fades out. So I grab a new filter, spin it on, and after about 10 minutes of working on it, it starts up and stays running. It ran the rest of the night. That means I loaded up one 10 micron filter, and put on another.

I pour out the fuel in the bad filter to check it, and see very small tiny particles of black material floating in it. My guess, hose material.

Now the boat ran all weekend on the second 10 micron filter. But here's the catch, I could only run on the Primaries. As soon as I opened her up enough to engage the secondaries, she'd run for about 10 seconds, and fade out fast. I don't know if that's because of the 10 micron fuel filter slowing the delivery, or if I have some of this black hose material up in the carb since the 21 micron filter may not have stopped it.

The plan is:
-All new fuel hoses
-New fuel water seperator housing and 21 micron filter
-If need be a new fuel pump, but doubt that it needs that.
-Rebuild the carb, again, to clear out the fuel channels and needles.




Don't know what kind of shape I'll be in, or what the boss will let me do, but I know I'm off until September, and she's working that weekend, so maybe we can work something out. I'd be very limited so I'd need a good crew, but you guys could leave your boat and ride with me, along with Brandon and his wife if he wanted to.

Just don't try and overdo it man.

[AaronWhitt82]

I would stay away from running Heet if I were you. It is mostly all alcohol.
It will attract water just as ethanol will which is not good for the fuel system....

[riveredge]

I would stay away from running Heet if I were you. It is mostly all alcohol.
It will attract water just as ethanol will which is not good for the fuel system....

Agreed, never add HEET or similar products to ethanol fuel, the fuel is already 10% or more alcohol, it will only make things worse.

See this article : http://en.wikipedia.org/wiki/Dry_gas

You're on the right track with replacing all the fuel lines and filters. I had to do the same with my 89, and haven't had a (fuel related) problem since.

[haugy]

I would stay away from running Heet if I were you. It is mostly all alcohol.
It will attract water just as ethanol will which is not good for the fuel system....


Agreed, never add HEET or similar products to ethanol fuel, the fuel is already 10% or more alcohol, it will only make things worse.

See this article : http://en.wikipedia.org/wiki/Dry_gas

You're on the right track with replacing all the fuel lines and filters. I had to do the same with my 89, and haven't had a (fuel related) problem since.


CRAP. Well, didn't know that. Thanks for the info. That might be why it also ran better over the course of the weekend as I added clean non-ethanol fuel to the tank. I found a gas station that has ethanol free fuel, and I'll be buying from them.