2001 Air Nautique /GT40 stalling problems

[RJP56]

Have a 2001 Air Nautique, 250 hrs, with GT40 engine that will stall or not start. After a little while, engine will start again. Definitely seems like a lack of fuel issue. Some history, bought the boat second hand a couple months ago. Was serviced and supposedly changed fuel filter. also gave me a spare. When boat dies, I push down the schrader on the FCC and get a squirt of gas. Push down the schrader on fuel rail by distributor and I get a hiss of air then gas. Open 1/8 pipe fitting on bottom of FCC and get a small amouint of gas. Low pressure fuel pump runs when the engine is turned over. Boat ran fine first 20hrs, except for a few times when it seemed not to take the gas when you pushed the throttle down. Last 10 have been a real headache! All fuel lines look fine. My first guess would be fuel pump. Any help will be much appreciated! Boats back home and will be trailered til nap time.


2001 Air Nautique
1989 Ski Nautique

[DanielC]

RE: 2001 Air Nautique /GT40 stalling problems

Check the fuel pressure. It must be within spec. Search, using "DanielC" and there is a thread on doing the fuel pressure check I wrote up.

[RJP56]

All Pressures check out alright when the engine runs. Have to wait til it stalls again then check. Anything else I could look at when boat runs?

[RJP56]

Finally had a chance to take the boat out this weekend after a month and a half of crappy weather here in NW CT. First few times out this year, no problem. 2-4 hours each. Went out yesterday, ran fine for 2-2 1/2 hrs. , then motor just died. Wanted to catch, but seemed starved for fuel again. After about 15-20 minutes would fire and catch, but give it any throttle and it would die. 1 1/2 hours later, started right up and runs fine. I was going to invest in a fuel pressure gauge this week to check pressures. Pulled FCC can off tonight and found one nasty filter. Plastic of the filter was swollen to bottom of FCC can and I had to pry it out with a pick. Came right off HP Pump. It was supposedly changed last Aug. when we picked boat up from dealer. Boat has 250hrs. total and we have put about 40 hrs. on it since we owned it. Can a filter get this dirty in that short a time? Gas has come from multiple stations. Noticed HP Pump was corroded on bottom. Is this from water in fuel? Should I just change it or still do a Pressure check on it? On bottom of FCC bowl I noticed a little pitting, again is this normal? Also a couple of tiny pieces of dirt or rubber in bottom of bowl.

[M3Fan]

That pump sure doesn't look right. Every time I change the FCC filter, it is swollen and stuck in the canister. I have to pry it out every time. And, it does usually look like that filter- maybe a little less dirty but that's in the ball park. I think the fuel itself stains the filter yellow to some degree.

[RJP56]

Another question/observation. While looking at the HP pump, I noticed the hose
that connects it to the top of the FCC can has hose clamps on it that are factory
crimped. They can't be tightened up. I can pull off the HP pump from this hose fairly
easily. In my opinion, not tight enough to hold 38 psi. If the HP pump is putting out 38 +/- psi, could this hose be getting warm and expanding allowing some of that pressure to leak back to FCC can?

[RJP56]

Observation: After fuel filter dried, doesn't look nearly as bad.

[RJP56]

Finally seem to be closing in on the problem. Boat died again today but I was ready. I opened the drain on the FCC and only got a few drops of gas out of it. While cranking the engine, I listened to the Low pressure pump with a mechanics stethoscope and could hear it running even though the boat wouldn't start. Opened the FCC again and almost bone dry. Going to replace the low pressure pump tomorrow. Doesn't make sense to me why it could be intermittent but a lack of fuel at the low pressure pump would seem highly unlikely I think. Ya I had gas in the tank. Boat started fine a couple hours later!

Any other ideas?

[M3Fan]

Just because the LPP is making noise does not mean it is functioning. Mine sounded like it was running when it failed.

[RJP56]

When I said it was running, I meant electrically. I don't think that necessarily means its pumping fuel.

What do you think?

[DanielC]

The output of the low pressure pump should be 5 to 6 PSI, and it should have good flow.

[RJP56]

Thanks! The output was a Big "0".

[RJP56]

What do you do to pinch off the fuel line to to low pressure pump when changing? Would a couple of small pieces of wood held by a Vise Grip be alright, or does this line have a steel braid inside?

[M3Fan]

What do you do to pinch off the fuel line to to low pressure pump when changing? Would a couple of small pieces of wood held by a Vise Grip be alright, or does this line have a steel braid inside?

No pinching off necessary when I did it. IIRC I just elevated the hose a little bit. Gas didn't gush everywhere or anything like that.

[DanielC]

It your anti-siphon valve does its job, very little fuel should leak out. Put a rag inder the pump before you start, to catch any drips. Remove any liquid gas in the bilge, and run the blower before you start the boat.
Here is how to check the fuel pressure without having to run the engine:
http://planetnautique.com/index.php?...+fuel+pressure