GT40

I see the first post says "solved" but I don't see the resolution in this thread..... What was the root cause? I have the same symptoms on a 1997 GT40. thanks

Sorry I typed wrong I had replaced both relays on the back not the ecm. I am just so skeptical about it being an exam because of the way the problem arises. I'm going to try a regulator. I may take the boat to someone after this. The cheapest I found an ecm
for was 675.

Lewy the boat did start with the tps off and WOT. I discovered this weekend with the FPR hose off the boat fired no matter what. It was odd i fired the boat with the hose off then put the hose back on and it chugged like it would barely run until it finally smoothed out. There is no evidence of fuel in the hose but it did smell terrible of fuel. I am thinking the problem is in the fuel system here wether a pump or regulator I am not sure yet. I did apply vac to the regulator and it did hold.

Lewy I have but I forgot to post the result and dont want to say what it did and did not do I will post back here soon with the results probably wont be out at the lake till this weekend but I want to say YES it did still start at WOT.

I replaced the injectors

Replaced the ect but also measured resistance before and it was good. For the $10 the sensor costs

As of now I am pretty much shooting in the dark here and using this post to keep track of the zillion things I have done.

Condition:
Boat fires right up pulling off the trailer. Drive short distance say 100 yards to the dock park the boat come back in about an hour sometimes boat will start and die others boat does not even fire it seems. After some extended cranking plugs are wet. After no start must WOT to get boat to fire then runs good until next long shutdown. I am currently throwing out the overnight cause because it does not seem to offer anything. Seems after first fire then shutdown is the real issue.

Tested/Replaced:
Fuel Pressue:40psi cranking
Map Sensor
Fuel Injectors
IAC Valve
ECT Sensor
Ignition Coil
Distributor
Cap/Rotor
Plugs and wires are around 1-2 years old with maybe low runtime.(Have a new set on the way)
TFI Module
ECM and F/P relays are only 1 year old.
Have Injector Pulse while cranking.
Have Spark while cranking.

Thank you everyone for your help especially Lewy. Even though I never physically could catch my injectors acting up I replaced them anyways just out of a good suspicion after i drove the boat 15 feet shut it off came down a hour later and needed to wot to get it to fire. Seems faulty injectors were my culprit.

Well back again I've searched a few times and cannot find the info I'm looking for. Does anyone have wiring diagrams or a repair manual for the actual boat and not the engine. Vince from skidim advised me to check out my keypad and I'm not sure how it works but I'd like to test it.

Ok I'll have to order that. My thoughts were also the variables. Like how much water is in the coolant passages when I pull the boat. I really leaning far away from a fuel issue but the gas in the tank is another thing that is moved a lot, I know very unlikely but could it be a vapor issue. The vent in the tank seems clear as I blew into it. The whole pulling the boat deal is what throws me the most. I'd hate to take it somewhere because they will more then likely throw parts at it and cost me money. I can throw parts myself but at least I can return them.

Lewy I posted the garage info a few posts up. Things that make thr condition happen. Leaving the boat in overnight, running for 5-10 minutes come back down boat is not gunna fire unless wot. If im sitting with friends for a few hours wot ok first start. The odd thing like I said is if I pul the boat and put it back in the next morning first startup would not be an issue. Thanks for all the help you have been giving.

And ecm heatsoak doesn't make sense to me. If I were to pull the boat every night it would start every morning without an issue. When I leave it in the water overnight wot is a must in the morning.

Andrew, I would remove the TPS from throttle body but still electrically connected and see if it is actually having the throttle butterfly open that is helping the restart (correcting an over rich condition). Not the different resistance from the TPS at WOT that is allowing engine to start.

It may be a ECM heatsoak problem but I hope not.

Ect sensor checked ok after going a few more pages found out those resistances should be in Kilo ohms and not ohm.

Why the Coolant Temp Sensor you ask?

When this sensor isn't working, the ECU has to assume the engine is cold and makes a richer fuel mixture, kind of like a choke.

When the engine is actually cold, this assumption is correct and it starts fine.

When the engine is warm, this assumption is NOT correct, and the engine won't start.

However, when you give it WOT it overrides the enrichning mode and goes into the flood clearing/less fuel mode which allows it to start.

That's my story and I'm sticking to it.