engine cuts-out GT40 EFI

I have a 95 Nautique with GT 40 EFI engine. The boat has 450 hours on it. This is my second season with this boat, and this problem was present last season, but worsened this year.

Boat starts great, runs strong, does not miss or sputter. Intermittently the power will drop, or cut-out, perhaps for a second or half a second. Enough to throw you off when reaching for a bouy. This may happen 1 to 3 times a pass.

I changed the in-line fuel filter, which was so clogged you could not blow through it. I took the boat out and it ran beautifully for 3 or 4 runs, then started dropping out with a vengance. Almost worse than before. I pulled the fuel tank an checked the screen on the end of the line which was clean. Tank looked clean. There was a bit of debris in the angle stop that comes out of the tank, so I removed that.

Last night I took it out to the lake, but did not ski. I ran it for 30 to 40 minutes and it ran like a charm. My friend & I took a 20 minute swim, when we started it up it dropped out for a second. Disaapointed, I came in and it drpped out only 1 more time.

The only other clue I can offer is that when it does drop out, and you I am behind the boat, I can smell a rich-fuel-exhauts smell.

Is it fuel? Ignition? A ghost in the machine!

Thanks for your help.

The motor never actually dies, it drops a few hundred RPM for a moment, and goes back to where it was.

Any ideas where to start? I've read other entries in this forum, and there is a lot of talk of fuel pumps, relays, kill switches.

I have read some of your posts, I believe. Sorry you are having such a hard time. I also have an appointment with the dealer next week. My concern is that it is so intermittent enough that they will take 500 bills and say the motor is fine. The condition can't be replicated in the shop. Even on the water. Seems I need a skier reaching for a bouy at 28 off to create the problem.

Keep me posted.

To The Dude:

Thanks for the advice. I will take some of these comments to the dealer. Frankly the dealer has been of no help. I mentioned what was happening to my boat, and their head mechanic said, "If I were God, I could tell you what is wrong, but I am not God." Bit of a smart a@#, eh? You would think that their career being dedicated to a certain boat, they could tell you something, anything. There are patterns in any discipline that repeat. What are the patterns with this model?

I was hoping on this forum I would have 10 good hits from others out there who can get me pointed in the right direction. I can turn a wrench, but need a start.

Any SN owners out there who can Help?!

Just back from the lake...

Boat plain old would not start. I noticed when I turned the key, the fuel pumps weren't pressurizing with that few seconds of ticking. (I learned that one from another thread). I pulled the relays, put them back, in...Voila! 22 passes on the course without a hiccup. I will replace those relays tomorrow.

Next problem: Any remedies for a sore back from too much throw-down!

Later.

1998Nautique:

Believe me I am no expert. What I have learned about these boats, I have learned from these forums. This is what I did, and would have continued to do: Isolate the fuel side solving from the ignition side:

on the fuel side: By pass your fuel tank by hooking up an auxillary fuel tank directly to your low pressure pump. That will eliminate any questions if it is a tank fuel line issue. put a fuel pressure gauge on your fuel injector rail. If your pressure drops, you know it is fuel related. Should be steady 40 PSI. May need to replace fuel pumps. Start with the low pressure, next the high pressure. You fuel pressure regulator (that valve looking thing on your fuel injection loop) may be not working. May replace that. Check for leaks and soft spots on hoses on this loop, too. I don't think it is an individual injector problem, if the whole motor is dropping out. Also there are lots of little screens in your fuel line. Check the one right as the fuel enters the low pressure pump.

Ignition: Replace the fuel pump and ignition relays. Mine are on a plate, mounted at the back of the motor. 12.00 each! Check all of your electrical connections. I mean all of them. Especially ones closest to motor heat. Undo them and look for corrosion. Someone suggested reconnecting them with dialectric grease. Start the motor, wiggle all the conections and wires, to see if something is loose. Check all of your ground connections. Not sure how to do this, put I read that idea. Check for a corroded connection where the main wires come off the ignition coil. If you have a kill switch on a lanyard, check it. One fella said to replace it, or bypass it. That the whole motor drops out v. running rough tells me it is not likely individual cylinder not getting a spark.

Also that the problem persists under load, which means lots of heat, it may be electrical. The experts tell me that failing electrical components, or connections are sensitive to heat.

Thats ALL I know.

todicus:

Nice job! I took 32 passes at the course this weekend and I am shredded, hands, especially. It is nice to be back on the water.

Where is that fuse anyway?

By the way, I talked to the West Coast Nautique distributor, and he says many of the 90's boats are notorious for electrical problems. He says most of them are connection and corrosion related. He said some years they had to replace the whole harness due to poor connections. It would have been nice if my local dealer had kindly pointed me (and you) in that direction.