1997 Ski Nautique Fuel Pump Issue

[sphodros]

Hello All,

I am new to the forums, however, my problem is not. Have a 1997 PCM GT40 ProBoss with a low fuel pump that is suddenly not priming/cycling. Have checked a variety of things including: relays (replaced), voltmeter at the fuel pump shows it is not getting power, removed the computer and no obvious corrosion (or other issue) visible, grounds all look good. We have looked at the "Hope for GT40 EFI ECU" forum thread with great interest, wondering if there are still people with the skillset and willingness to help us get a new Moates chip programmed to wed to either our ECU or a replacement? Also happy to hear any alternate suggestions of things we should check for/try!

Thank you in advance, always devastating to be blocked from getting out on the water, shame on us for not having a backup (hope to remedy this problem with the fix as well)!

[Tom_H]

I'd be trying to back-trace the circuit to figure out where you're losing the power before jumping straight to the computer. I could see a bad kill switch or bad ignition switch causing an issue here, as both when faulty could interrupt the run signal but still allow the engine to crank.

[sphodros]

Thank you for that feedback! I've ordered a replacement kill switch just in case. One of the major issues is that I don't actually live near the boat, it's at my parent's place so I don't have the ability to troubleshoot on a regular basis (and my dad is not the proactive purchaser kind of guy, so my brother and I are in charge of making sure we have as many possible parts on hand to swap out when we are there to fix).

Question for you: how do we diagnose it if is a bad ignition switch? I've been trolling the forums looking for a clear answer, any chance you can point me in the right direction?

As an update, I also went with getting a Moates chip burned and a new (to me) ECU to have as a backup if nothing else as they are not getting any more common and would rather have it and not need it than miss out on a precious weekend on the water again. Will continue to update as we find the problem (wont be back at the boat for another few weeks).

[beamons]

There a a lot of things that are more likely problems before the ECU. Here are some of the most likely problems causing the issue:
First and most likely, there is a fuse that is right off the battery that can either blow or just have some other connection issue. Check that and if that it is good and getting power through it.
Second check that the kill switch(safety switch behind the throttle) is not unplugged or clip has fallen off or missing. If needed pull the wires from behind it and bypass with a wire.
Third, the relays in the back by the ECU are common issues that cause the fp to not cycle.
Fourth, loose wires on the bottom of the fuel pump.
To replace the fuel pump it is an easy thing and not terribly expensive, if it has never been done I saw a significant performance increase when I changed mine. This is a replacement from amazon. https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

All else, I have a spare ECU that I would be willing to sell. I know it works.

[sphodros]

More excellent feedback, thank you, beamons! Since my original post, my dad has let me know he checked the battery fuse (is fine) and the FP relays have been replaced with brand new ones without fixing the problem. Will check the kill switch and FP electrical/wires next. Pump has been replaced once before, but obviously does not mean it doesn't need to be replaced again. Updates with each test we do as we trouble shoot, hopefully I can still get in some slalom time this year!

[FMSKI]

Is the FCC HP pump priming or are both the pickup and FCC pump NOP? (not operative). Kill switch the engine will start and die IIRC.

Key on (no start) the pumps will spin for 2-3 secs, then stop.

[sphodros]

I'm not sure about the HP pump, will have to double check that. The boat does crank but does not start at all which seems to be different symptoms than a bad kill switch which, as you say, should mean the engine starts and then dies (I think).

[Tom_H]

Kill switch interrupts the 'run' signal off the ignition (which includes the fuel pump power). So, a bad/tripped kill switch will allow a crank but no start. It may start and die if you have some residual fuel in the line if it had been running previously, but if it hasn't worked for a while, I wouldn't expect it to start at all.

[sphodros]

Oh-ho, thank you for that clarification, Tom_H! I was getting confused reading over the forums what the definitive symptoms of a bad/tripped kill switch are. That is still in the running as the possible cause of our ills then, I will be at the boat next weekend and will test out what is mentioned here and post an update with a (hopefully) running boat at the end of the dock.

[sphodros]

Ok, update from the lake. We have now replaced:

1. The kill switch,
2. the ignition switch,
3. the computer using an ebay + moates chip (major shoutout to t.franscioni for programming the chip for us!), and
4. all relevant relays

and confirmed that:

5. the fuse on the battery is good (all contacts look clean, fuse itself transmits based on multimeter reading).

Unfortunately, none of them solved the problem. The low pressure FP is still not getting any power (using a multimeter at the contacts on the bottom).

Next steps:

- Will double check the HP fuel pump situation as per FMSKI above,
- Will check for loose wires on the fuel pump as beamons suggested above (although I assume that no power at the pump itself rules this out)
- Then try jumping the fuel pump directly off the battery tomorrow to hopefully get the boat running long enough to get it out of the water so we can bring it to a mechanic to look it over, unless anyone else here (please please!!) has any other ideas?

Thank you again for all the help so far, fingers crossed we can still avoid paying for a loose wire snipe hunt!

[gary s]

There is a diode in the wiring harness- I have heard it can cause trouble. Don't know where it exactly is though, a search here or on Correct Craft Fan will likely turn it up as I remember it being discussed. It's replacement is like 2 bucks

Found it- https://www.correctcraftfan.com/foru...g-sporadically

[sphodros]

Whelp, the boat is at the mechanic, I will update here with whatever they find. We ran out of time to keep troubleshooting, and then when we went to tow in the boat the the boat launch, our lift broke. When it rains it pours, hopefully the fixes for both will be quick, easy, and cheap!

[sphodros]

Hello All,

Update after the mechanic solved the issue, as promised. It's a photo of the documentation they sent back with the boat, hopefully it helps someone someday!

Looks like a real gremlin that the mechanic ended up just totally bypassing with the addition of a new wire. I did not have the opportunity to talk directly to the mechanic, so cannot add any additional information to what is written out.

[Scooter G]

Nice write up sphodros from start to finish. Read like a good Detective Novel, can't wait for the movie to come out, thanks for the share.
Electrical problems can be mind blowing, not to mention lost sleep. Sounds like you are ready for this Season's runs, um, once the ice melts...

[bturner]

Pretty darn good tech. I'd keep his number in my phone's address book.