1997 gt 40 troubles

[barefoot111]

Hi,
New to forum. I have a 97 ski nautique w/ the gt 40 efi. I have been towed 3 times this year. first trip out, it ran fine. I ran it about 2 miles across the lake. I parked it about an hour then started it to head back home. It ran about an eighth mile then cut off. no hesitation at all. would turn over, but not start. local dealer said to replace fuse link in battery box and replace fuel line that connects to fuel pump in cell. they said both gave problems. I also replaced the filter. took it out again. Ran fine, pulled skiers, played around, ran perfect. let it sit for about an hour then tried to head to the dock. ran fine for a short distance then died again. This time it sputtered. would not start back. I checked the spark with a screw driver and it was firing. I found that the small screen in the pick up tube at the anti syphon valve was completely blocked. I cleaned it and took it back to the lake. ran perfect. ran about 45 mph for about 2 miles to get to smooth water. from there I pulled 3 barefooters for 2 sets each. then it sputtered out and died. I got it home and checked the screen in the pick up tube again and it was clean. any ideas? Is this a common problem? I am lost at this point. I do not want to start replacinf fuel pumps or relays without knowing that is the problem. I also ran sta-bil for the winter, and run startron in every tank to combat the ethanol problem everybody is having. Thanks for your info.

[M3Fan]

RE: 1997 gt 40 troubles

Perhaps next time it happens you could confirm that you're getting fuel pressure?

[jjgag60]

gt-40 troubles

I also have the gt-40 and the 300 page manual on this site helps a lot. My dealer says 90 percent of the problems they have with the gt-40 is gas related. I just purchased a used pressure tester for the EFI and it helped me trouble shoot my problems. Daniel C has some great post on how to check the pressure. Start there and look at your FCC. There is a lot of talk about the small hose that runs between the HP and LP pumps. If one of your filters is already clogged you may have other gas related problems. The relays are only about $13.00 at NAPA. Good luck

[eseybold]

RE: gt-40 troubles

I have had a similar problem with drop in performance after 2 winters storages ago and to this day still get hesitation when getting skier out of water. I have 2000 GT-40 SNOB. I have changed all fuel pumps, checked pressure, fuel lines, fcc ,complete tune up, timing check etc. My only conclusion at this time is bad gas( ethanol) and a possible knock sensor problem. Check your fuel pressure - very simple to do.

[barefoot111]

RE: gt-40 troubles

I am going to check pressure tonight. What should the pressure be at? How can you tell if it is the high pressure or the low pressure going out?

[barefoot111]

RE: gt-40 troubles

ok, here is what I found. turning the key on yielded 35 psi, and idling yielded 28 pounds. The local nautique dealer said it should prime between 40-44 psi and idle no less than 35 psi. I removed the fuel pump and put it in a bottle of gas with the gauge hooked to it and it almost maxed the gauge out. Does this rule out the pump? If so, does it mean that I have a regulator problem? I also unplugged the high pressure pump and tried to get a reading from the low pressure pump by turning the key on, but it barely moved the needle (I had the gauge on the fuel rail for this test too). Is the pressure controlled by the 2 relays by the ecm? I noticed that one had been replaced by the previous owner. I am still stumped, but maybe getting closer

[horkn]

RE: gt-40 troubles

Well, I am happy to hear youa re not blaming the e10 gas.

I have been running e10 for 15+ years and have yet to have an issue with it. Yeah, it does not store as long, and it gets a little less mpg, but it has higher octane, and won't ice up.

I have a feeling it is an electrical issue with the relays.

[M3Fan]

Re: RE: gt-40 troubles

ok, here is what I found. turning the key on yielded 35 psi, and idling yielded 28 pounds. The local nautique dealer said it should prime between 40-44 psi and idle no less than 35 psi. I removed the fuel pump and put it in a bottle of gas with the gauge hooked to it and it almost maxed the gauge out. Does this rule out the pump? If so, does it mean that I have a regulator problem? I also unplugged the high pressure pump and tried to get a reading from the low pressure pump by turning the key on, but it barely moved the needle (I had the gauge on the fuel rail for this test too). Is the pressure controlled by the 2 relays by the ecm? I noticed that one had been replaced by the previous owner. I am still stumped, but maybe getting closer

The key is to check the pressure when it dies next, to know if when the problem occurs it is due to fuel pressure.

[nms1991]

RE: Re: RE: gt-40 troubles

On the low pressure pump you need to do a volume test. To do a volume test you need to remove the line from the low pressure pump to the fcc at the fcc and put it into a 20 oz pop bottle and turn the key on and let the pump work until it times out with the computer and then empty the pop bottle and then reinstall the pop bottled on the fuel line from the low pressure pump and then you need to use the diagnostic connector on the back of the engine and use the triangular shaped connector and find the blue w/ orange tracer connector and ground out the connector and count to 10 seconds and if it does not put out 16 oz or more then you have to look at either the pump or the fuel lines to the tank. but when it does cut out the boat does have fire but the pumps do not run? or do they run? If they do not run then the relay is more likely at fault than the pump, but if the pumps work and it still looses pressure then the low pressure pump is bad.

[barefoot111]

RE: Re: RE: gt-40 troubles

Thanks everybody for all the great info! I did a volume test tonight. I got 12 oz in 10 seconds. I know that the anti syphon valve and the pick up are clean. I also know that when it acts up and won't start that I can turn on the key and here the pump fill the cell. Is this the missing 5 psi I had on the pressure gauge, and would this be enough to cut a motor off? Maybe it gets weaker when it heats up? I have new relays to install, but sounds like this pump is the problem. Is there something in the ecm that cuts it off if the presuure is too low? Is this the smoking gun?

[barefoot111]

RE: Re: RE: gt-40 troubles

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[swooddc]

RE: Re: RE: gt-40 troubles

sorry if i missed this and am repeating someone else. Have you checked the little hose inside the FCC that connects to the high pressure pump. these can fail, leading to a drop in pressure.

by the way, do you have the part numbers for the relays? I am working through a similar problem and want to pick some up before I go back to the lake where the boat is.

[bwana50]

RE: Re: RE: gt-40 troubles

Deja vu! I'm having the same warm-start problems with my '96, with the exception that mine has never died during an "initial" run. If you find a solution let us know.

[DanielC]

The GT-40 engine does NOT have have any feedback to the engine computer on what the fuel air ratio is. It also just assumes the fuel pressure is correct.
You have to do a fuel pressure check when you are having the driveability problem to diagnose the cause of the problem, if it is intermittent.

[nautiquejimmy]

if the fcc hose is a clear hose, these were recalled. (I dont remember the year) also, is the check valve at the fuel tank working properly? sometimes the ball gets a little sticky. If all lines are free flowing and this problem occurs, i just open the fcc and confirm its full. If its full and all lines are free flowing, I would be suspect of the high pressure pump. If not, then the low pressure pump is in question. good luck