GT-40 EFI Engine sputtering, ECM relay or FCC???

Hi

I have a CC 97 with GT-40. It is mainly used for slalom skiing at 34mph. I use the boat all year with no more than 2 weeks unused.

A few weeks ago, I used the boat to ski. We skied about 4-5 sets and the boat ran fine until it chocked for 1 sec at 34mph, before the gate. It was like the power died for 1 sec and came back. It was short enough for the skier to complete the pass. The boat ran fine thereafter. It was about 50F air and water.

2 weeks later I used the boat again. Same thing boat starts perfect and we ski a few sets until it did the same thing again. This time I notice that the "check engine light" came on for 1 sec while the boat choked.

On the next pass the boat did it straight away but a lot worse choking several time with a strong smell of gas.

We decided to go back to the dock with engine running fine on idle.

The only thing we noticed is the exhaust manifolds are colder than normal and while the temp gauge is moving, it seems that it is moving a lot slower.

Our theory was that the thermostat is malfunctioning and instead of opening progressively, the engine gets hot and the thermostat opens suddenly which causes the computer to over feed the engine with gas choking it.

Would it make sense?

Last service was within a year and impeller, oil filter, fuel filter... were replaced. Spark plugs are 18 months old and thermostat was replaced 1 year ago as the old one was stuck open.

Thanks

ricofrancois wrote: Our theory was that the thermostat is malfunctioning and instead of opening progressively, the engine gets hot and the thermostat opens suddenly which causes the computer to over feed the engine with gas choking it. Would it make sense?

If you are taking a poll I would say no. I have never heard of this happening, not even sure it is possible. What is there for computer diagnostics out there for this engine? You need to find out what might be triggering the CEL. I think Jody is selling a PCM service manual. I would pick up the phone and start calling CC service departments.

SN206 Did yours stall or ran poorly otherwise? Mine is only under load at 34mph or after getting up a skier.

Hollywood, I think I agree as the thermostat was replaced not too long ago. The CEL may have turned on because the engine almost stalled before power came back but I will check if I can get a read on the fault stored.

Bri892001 Lanyard or ECM relay would be cheap fix

I am going to the lake on sunday and will report back.

Thanks to all

The impeller was replaced last march and the manifolds were definitely warmer with the new one but could be wrong.

The gas smell was out of the exhaust.

I would check over electric connections make sure all are clean and tight.

ricofrancois wrote: This time I notice that the "check engine light" came on for 1 sec while the boat choked.

This is the critical bit of information you have either a faulty SLOW (limp) mode oil pressure switch or the faulty SLOW mode temp switch. These switches are additional to the senders for the temp and oil pressure gauges. There is also the possibility of a SLOW circuit wiring problem.



You can test this by just disconnecting the wire from both of these SLOW switches.

Is the engine running at normal temps 160 ish?

I have some pictures of the location of these SLOW switches that I will post when I get on the right computer.

I was going to suggest oil pressure switch or wiring issue yesterday but decided to keep my mouth shut as I'm not too engine-savvy but my '96 did the same exact thing after Woody put the new GT-40 heads on it a couple years ago. First water test after the new heads were on I backed it off the trailer and idled out, ran great. As soon as I got into it it did exactly what the OP described. Turned out a loose connection to the pressure switch.

It is inside the FCC.

Is the engine check light still on as stated previously? If so you are getting way of track.

Eric, these switches are additional to the gauge senders with the oil SLOW switch you can see the gauge sensor clearly right next to the SLOW switch. The temp slow switch is in the top of the inlet manifold mine is a bit more obvious as I have a "T" and 45 degree elbow in original inlet manifold location for a heater. The temp gauge sensor is in the circulation water pump.

OIL SLOW SWITCH


TEMP SLOW SWITCH

Here's a write up of another member with the same issue...

http://www.correctcraftfan.com/forum/forum_posts.asp?TID=21983&title=pcm-gt40-backfires

Keep Wetskier2000's suggestion in mind too. Considering how frequently that little tube fails, and how relatively cheap it is to fix, it's worth checking, even if it's just to cross off and move to the next suggestion.

wetskier2000 wrote: Here's a write up of another member with the same issue... http://www.correctcraftfan.com/forum/forum_posts.asp?TID=21983&title=pcm-gt40-backfires

For the convenience of all, here's a proper link

Sounds good so far...

Yes, the relays.. I keep a spare in the boat...

Do you have a CEL when the engine is running? If it's only on with key on, engine off, isn't that normal?

Finally did my manifold leaking repair this year also...

I wish I was skiing but it's 16 degrees here right now...

If the CEL light is not coming on with engine running then it will not be the SLOW circuit being activated causing the problem. Maybe you should have been more clear with the symptom description.

The first thing you need to verify is the fuel pressure at both idle (31 +or- 3 psi) and just ignition key on engine off (39 +or- 3 psi). You can also check your pressure at WOT or with the vacuum hose removed from fuel pressure regulator for max fuel pressure. The relays could be the problem but a fuel pressure gauge will help confirm. The computer will not store a code for low fuel pressure.