Long Running Stalling then No Start Issue - GT40

Hi Guys,

I own a 97 MB Sports LS200 ski boat with a GT-40 engine that has a Fuel Control Cell.

For the past 2 years, the boat has been having this intermittent issue where it will stall while it's driving and won't restart for a long period of time (from hours to days).

When it stalls while driving it won't restart. The motor cranks just fine and it turns over and over but never starts. This weekend was a great example. Yesterday we skied hard from 9-1pm just fine without an issue. Then when we tried to start the boat up after lunch, it wouldn't start. Just cranked and turned but didn't start. We couldn't get it going for the rest of the day. Had to be towed in!

Earlier this week I changed the fuel filter and tube inside the FCC and yesterday it ran so much better than it has in the past. The boat maintained it speed at 15-20mph better than it ever has - it usually surged around at those speeds.

My hunch is that it is a fuel delivery issue. The boat cranks great, but it sounds like not enough fuel is getting through. What's confusing me is that that last 2 times I've gone out it has done the same thing - ran great in the morning - sat for an hour at lunch and then won't start again after lunch!

What else can I try? I'm going to try change the anti-siphon valve next, but I also read on these forums about possibly changing the relays and checking the fuel pressure.   

Wanted to get your thoughts on what the best next step would be - or if anyone has any ideas as to why the boat is acting like it is. I'd put money on the fact that if I threw the boat in the water today it would start just fine! Makes it so tough to troubleshoot!

Any help would be appreciated!

Steve

Take a look at this thread also:
http://www.correctcraftfan.com/forum/forum_posts.asp?TID=25584&title=poor-mans-gt40-diagnosis

I'd be thinking relays. Keith's TFI post towards the end sounds similar to your issue but it's less common.

Check for spark when it will not restart. Also you should hear both pumps do their prime cycle with just ignition on not cranking. This is always a good stating point.

Next step is check fuel pressure if you have a suitable gauge.

See if it will clean up with a soak and maybe some aluminum cleaner and a wire brush first and replace the TFI.

Lewy is right on though, many hundreds of dollars can be saved by bringing along a timing light and when it dies looking for a spark. If there is no spark you can stop looking at the entire fuel system, if there is a spark you can stop looking at the entire ignition system.

I think the TFI is one part that actually is ok to get through an auto parts store. Read Keith's posts about the TFI about halfway down:
http://www.correctcraftfan.com/forum/forum_posts.asp?TID=25584&PN=2&title=poor-mans-gt40-diagnosis
to make sure you're getting the correct one.

Their was some business about the black vs grey, remote mount etc.

+1 on what gun driver says, just clean it the best you can,the money you save use for gas!

Hi Guys,

I've cleaned off that oxide coating and replace the TFI and just need to find a time to drop the boat in the water to test it out. I also replaced the 2 relays just in case!

I did purchase a fuel pressure gauge, but have no idea where to connect the thing to test the pressure. Can anyone guide me in the right direction?

Thanks a bunch!

Steve

Hi Gun-Driver - thanks very much! Found the valve - now just need to take the boat out and wait for it to fail and then test the pressure!

Should I test the pressure when trying to start the boat? Or just when the key it turned on (before the crank?)

Hi All,

Well took the boat out today and skiied from 10-1pm without issue. Docked for lunch and then minutes after taking off and driving at about 30mph the boat spluttered and stalled and wouldn't start.

Luckily I had my fuel pressure tester and hooked it up (a tiny bit of fuel came out as I was screwing it in but the pressure tester showed 0 fuel pressure. How could that be? I took it off and some fuel came out of the tester and then I reconnected it. Still 0 pressure when ignition was turned on. The fuel pump did prime but 0 pressure.

What now? Could it be the anti siphon valve preventing the fuel being delivered to the engine? Or something else?

Thanks for all your help!

Another update. So towed the boat back home yesterday and this morning I connected up the pressure tester and it showed about 30 psi when I turned the ignition key and then 40psi when I cranked it. The boat started just fine (first time).

So yesterday on the water when I was having the no-start issue the psi was 0. So definitely zoning in on the issue here but don't know where to go from here.

What would cause there to be no fuel pressure?

The TFI has been replaced at this point though, right?

Fuel Pump relay? The relay is going to be more prone to acting up when the engine is hot.
That hasn't been done yet, right?

This is really bad because my '95 is doing the same thing.
Starts on first bump of the starter when we first start out, runs great all day even after shutting off to change skiers then… when we stop for lunch and a swim for about an hour BANG no start. Leave the cover open for a half hour or so… starts right up and runs as normal.

Yours as with mine something is getting heat soaked as it sits with the engine cover closed causing the no spark or no fuel pressure condition and I thought I had it pinned down to the TFI as I have one sitting in my truck waiting to be installed.

So that leaves us with the two tests I mentioned check for spark if yes, jump the STO to run the pumps and go from there.
But I don’t think it’s the pumps since they work fine all morning till you park with a hot motor.

???I wonder if the pump is crapping out and getting hot but as long as fuel is traveling through it, it stays cool enough to work but once you shut down they heat up to the point of not working till you open the cover till they cool again??? I’m just thinking out loud through my fingers.

LEWY HELP I’M STUMPED.

Thanks guys - so tell me more about this fuel pump test? Where do I find a hot wire and where is the pump?! I know - simple questions, but I'm still learning my way around this boat of mine!! Appreciate the help.

MrMcD wrote: Just an idea after reading, open the Engine cover when you stop for lunch. Let most of the heat escape. Might keep you running.

Yes this is an option but I perfer to get to the root of the problem so the system works as it should.