1999 Nautique wont start if floating in water

[Mmarra]

I have a 1999 Nautique with PCM GT-40 EFI . It has about 800 hours on it. It starts up when in the lift and runs great pulling a couple skiers. We turn it off after each skier and it always starts up when we are ready for the next skier. The two times it has had trouble starting up was when we went for a slow boat ride about 100 yards from shore and then stopped to star gaze. The first time we sat for about 30 minutes and when we went to start it , it would turn over but not start. After a few seconds days of trying to figure it out I decided to changed the fuel filter and I got it to eventually start up. The second time we were in the middle of the lake for about 15 minutes and I decided to make sure the boat would start. It have a very difficult time turning over but eventually did. Both times we did hear a gurgling sound from the back. I'm assuming it was the exhaust flap not being closed. Could this be the cause of my boat not starting? Any suggestions or ideas are welcome.

[charlesml3]

Alrighty, I had the same boat for 17 years and yea, it could be a little "weird" sometimes. The first thing we need to investigate is heat soak. If we wakeboarded for a couple of runs and then sat for 30 minutes or so with the engine off, it would turn over easily, but sometimes be difficult to start. I eventually figured out it was heat soak. The heat from the engine was conducting to other parts of the engine when we sat. Is that what you're experiencing?

The other time would be when the engine was dead cold. It would start just fine, but it would "lope" until the engine warmed up.

So with 800 hours, have you done an ignition tune-up on this boat yet? If not, it almost for sure needs a distributor cap, rotor, and spark plugs. While you're at it, you should replace the plug wires too.

-Charles

[gary s]

In addition to the above,which should be regular maintenance items anyway try this- Next time it happens have someone turn the key on to the run position and try to hear or feel if the pumps run for a second or two.There are two relays mounted below the circuit breakers, on the engine next to the ecm,one controls the power to the ecm and one powers the fuel pumps. It's good to carry spares with you, you can get them on Amazon or White Lake.,google Hella 4RD 960388-31. They can cause trouble. Another regular problem is the low pressure pump. If it has never been changed you have been very lucky. They are not cheap if you go thru a dealer but there is an alternative,a Carter P 4389 pump. Google it or check ebay you can get one for around 60 dollars. If that does not cure it you'll need to get a fuel pressure gauge to test the system.There are other things that can cause trouble but these are common and a good place to start

[JD ski]

I have the same boat and motor. Once in a while the same issue occurs. It acts as if it is flooded. A little cranking and it fires up. As this motor is fuel injected (although port injected) flooding should not be an issue, although it is exactly how it behaves and getting it to fire requires the same procedure as a flooded motor. When it does fire it slowly roles to life. Just like a flooded motor does. So, it is either heat soak or flooding. All the information above is right on target. I usually notice this happening after the motor has been revved up and pulling and then rapidly shutting the motor off without a few seconds of idling prior to turning the key off and then as mentioned sitting for 15-30 min. These motors are not like a modern push button start motor that starts 100% the same every time. There is still some old schoolness to the GT-40 motor and it does not necessarily mean there is any thing wrong behaving as mentioned.

[DaveNH]

What do you mean by "in the lift"? I assume this is with the lift down and the boat floating, so no different from floating out on the lake somewhere? Only difference is cold start vs. warm start. My GT-40 acts like JD ski described, when stopped for short periods between skiers it fires right back up, when stopped for 30 minutes plus it takes some longer cranking but always starts. I haven't chased it as a problem because it isn't a problem so far.

Your problem sounds similar but with it not starting at all. I assume you've let it crank for 6-7 seconds to see if it would finally catch. Once you've done the ignition parts a fuel pressure gauge would be a good step in looking at fuel pressure for cold start and hot start to see if you have a fuel delivery problem.