GT-40 Issues

Hi,
I am having some issues with my GT-40 (Ford) engine. First off, the boat is not a Nautique... it's an MB Sports Boss LS200, but I figured this would be a good place to ask a PCM question.

The engine starts fine, but runs rough. It is not terrible at low speeds and low rpms, but after running at higher rpms for probably 20 minutes, the engine will begin to bog out. It will surge slightly at cruising speed and will then begin to die. Sometimes you can recover by letting off the throttle and slowly accelerating again. Other times it will just die off completely, but always restarts easily and will run again for a while until falling into the same pattern.

Fuel filter was replaced by the previous owner a couple years ago, but I have ordered another as these symptoms seem to point to the fuel filter. Any other suggestions? The GT-40 is the newer version with the FCC. I am trying to get my hands on a fuel pressure tester to check that also. Could it possibly be a spark plug issue? I pulled the plug boots off and the plugs looked a bit suspect.

Also, is there a filter anywhere inside the low pressure pump that could be replaced, or would the entire unit need to be replaced (if this were part of the issue)?

Thanks for the help

Also a good idea to check the anti-siphon valve. It is part of the fitting that comes out of the fuel tank. These are known to gum up and cause problems.

Also, check out some of the ideas in here:
http://www.correctcraftfan.com/forum/forum_posts.asp?TID=25584 and also look at the google spreadsheet contained within.

Be sure to update this thread when you find your fix.

Thanks for the replies. The boat is a 1997, with only 370 hours on it to date. We have already pulled the FCC canister apart and examined the high pressure pump and filter. The hose had been replaced at the same time the previous owner replaced the filter, and it looks good.

A local marina suggested that it could be clogged injectors, but after reading of other similar experiences and talking to the folks at skidim, most people seem to think that the filters do such a good job eliminating impurities that it is unlikely anything made it as far as the injectors, and that the problem is before them.

So, we plan to check the anti-syphon valve, drain the fuel tank and replace with new fuel in case it is just a bad tank of fuel, replace the fuel filter and O-ring, and see what happens. If we still have issues, we will then look at spark plugs & wires, and the fuel/water separator.

guitarist35jc wrote:    A local marina suggested that it could be clogged injectors, but after reading of other similar experiences and talking to the folks at skidim, most people seem to think that the filters do such a good job eliminating impurities that it is unlikely anything made it as far as the injectors, and that the problem is before them.

J,
I'm glad you did some research before taking that marina's advice. It sounds like they have no idea of what is going on. I sure would hesitate going back to them. They must be a Bayliner dealer!!

They aren't a Bayliner dealer, I believe they are a Sea Ray dealer... not much better hah. They were the dealer that the previous owner used to have the steering cable replaced not long ago, so we decided to try them since they knew the boat.

I wondered about the relay also, if I decide to swap it out should I do both relays at the same time? Or just the fuel control relay? Seems like fuel system problems can be a wild goose chase to track down.

Well, here's an update on our GT-40 problems. A new fuel filter arrived last week. We installed it today, as well as removing and cleaning the spark arrestor which was full of belt dust and other debris. We also removed the fuel pickup tube from the tank. The anti-siphon valve was seized in place and impossible to remove from the right angle fitting on top of the tank. What we did find, however, was a lot of gunk in filter at the end of the pickup tube which sits in the bottom of the tank.

So, we put the boat back together, put some fresh fuel in the tank, and took it out for a run. It ran smoothly with no hesitation, no surging, and no bogging out for roughly an hour. Before this work it was showing signs of not getting fuel about 10 minutes into running. So, it looks good for the time being! Not going to say it's fixed yet, as I'd really like to get a look inside the anti-siphon valve, but its vastly improved over a week ago!