GT40 Hesitation above 2500 RPM

[Gunnin4six23]

I have a '98 Ski with EFI GT40. Been running great this season till 2 days ago. once above ~2500 rpm the engine hesitates. Its not really a chugging as it is more of a total loss of power for an instant. Engine light is on. I can cruise at anything below 2500 with no trouble.

Feels electrical, but some people think it may be fuel delivery issue.

Any ideas?
Any help would be very appreciated.

Thanks

[2001SAN]

Is the check engine light on constantly? The light and limp mode (reduction to 2700rpm max) are triggered by either a fuel pressure switch or temp switch (not senders). Perhaps one is faulty? Check out this thread on cfc:

http://www.correctcraftfan.com/forum...k-engine-light

It shows a pic of there temp switch. The oil switch is just above the oil pressure sender which is mounted above the oil filter. Disconnect each and see if the light goes off.

D.

[Gunnin4six23]

Thanks D, I will check out the thread.
The light comes on after it starts to hesitate, then stays on till i shut it off, which will reset it. Light did flicker a couple times when i brought it down to idle.
When I first go out in the morning it will get up to cruising speed for about 30 seconds then start hesitating.
I did order a fuel filter as it has not been changed in a few years (yeah, not good). If that is clogged, It leads to your theory on the fuel pressure drop.

[Blamey]

I had very similar symptoms last couple weeks but for me it was only at WOT. I changed my fuel filter but still had issues. I fill up my tank with new gas this weekend and no issues since then.

The previous tank was filled up on at the start of the month but I figure it was bad gas or I somehow got a little water in there.

I haven't run the boat enough to be totally sure that the issue is gone but the issue started with the new tank of gas happens fairly consistently at WOT and has not happen since I filled up again.

[Gunnin4six23]

Interesting...I did fill up that morning. we were 3 skiers in though before it started. Do you think a dose of "dry gas" will solve?

[rdclark]

Sounds very similar to my problem with 98 GT 40, I can run for about 20min
before I get a hesitation during acceleration. I feel if is fuel pump issue, in the process
of replacing both pumps. Hope that fixes it. Let us know if you figure out your

[Blamey]

Interesting...I did fill up that morning. we were 3 skiers in though before it started. Do you think a dose of "dry gas" will solve?

I really don't know how well "dry gas" works, never heard of it before. Not sure what else you can do besides run the tank to near empty then refill and see what happens. I guess dry gas or something similar couldn't hurt to try.

How frequently does the hesitation occur. For me it was once every minute or so and only at WOT, so not a big deal.

Edit: I also wanted to add that when researching this, I found there could be many reasons for the hesitation but if it did start soon after a gas change then I'd start there before going on to more difficult investigations.

[Blamey]

Did you figure this out.

[Gunnin4six23]

So here is the latest.
I replaced the fuel filter with no improvement, still goes to limp mode with hesitation at around 2700 rpm.
Thanks to 2001 SAN link to correct craft fan forum, I was able to start trouble shooting through the temp and oil pressure switches with a friend who has more engine knowledge than me.
We started by disconnecting wires (2) to the temp. switch. I grounded the wires to the block and nothing changed. I kept them off (open switch) and nothing changed either. Not the temp switch.
Moved to the oil pressure switch. I didnt know which was the switch and which was the sender so I started with the closest item. Disconnected wire and grounded it and it caused the pressure gauge to pin so I know its the sender. I disconnected the wire from switch and the engine ran fine, no hesitation. Bad oil pressure switch. Just ordered from Nautique parts. Should be back to skiing this weekend.

The weird symptom (and what was throwing me off and others) was that it was fine till the engine was warm.

Thank you to everyone for the help!

Phil

[vortech347]

Check your oil pressure sending unit. You should be able to read trouble codes or have it read since it's a Ford EEC-IV system. My 99 GT-40 did the same thing and it was the Oil Pressure sending unit that is very easy to replace and is not very expensive.