GT 40 engine cut-out problem - Help!

[ToolBoy]

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.

[Onthewater]

RE: GT 40 engine cut-out problem - Help!

I am not great with EFI but check fuel pressure, make sure there isn't a leak.

It is very possible that it is an electrical/ignition issue.

[ToolBoy]

RE: GT 40 engine cut-out problem - Help!

Onthewater: Thanks for the reply. It has been all day and you are the only one. It is on my list. I got the pressure spec from the GT-40 manual I downloaded from this site. Any ideas on where to start with the ignition?

Anyone else want to chime in? I read up and down this forum and a lot of you have great ideas. Let's hear them. I keep reading about high pressure fuel pumps, relays, computers, kill switches. I want to get back to running the course, I don't want this to kill the summer for me. It is my second season in a killer ski club, and I am starting to think this year is a goner.

Thanks!

[ToolBoy]

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! :grin:

[BobbyGagnon]

hey ToolBoy,

i think my 98 sport is showing the same problems. i will be cruising between 20 and 30 mph then all of a sudden the engine light comes on and the engine sounds like its losing power with about 2 or 3 hesitations. however the engine never cuts off, i will slow it down or put the boat in idle and it appears to run ok. i have drained and replaced the fuel filter and still having problems. the relay that you speak of, is that where the positive battery cable runs to in the back of the gt40 near the breakers? have you replaced it yet and do you think i have the same issue.