GT-40 Pro Boss Engine starting / stopping issues

1995 Ski Nautique GT-40 Pro Boss PMC/Ford 351 EFI

Engine wouldn't start at boat ramp this morning Got it started at home, but now won't shut off.

Several weeks back, replaced fuel pump and fuel relay due to another starting issue. Have used it several times since and no issues.

Today, engine turned over but would not start at the boat ramp. I suspected the fuel relay since I did not hear it prime. I had messed around with the relay the other day to re-mount it as the replacement relay did not mount the same way as the original. I heard fuel pump prime when I was messing with the relay. (Ignition switch is off - shouldn't get power should it?)

I hooked the hose to the boat and was able to start it in the drive way, but went to shut it off and it did not shut down when I turned the key to off. I turned off the ignition switch. Still running. I pulled the kill switch. Still running.   I ended up pulling all the spark plug wires to kill the engine.

I suspect something electrical is messed up, but I have not done anything with the electrical system.

Thoughts ./ ideas / advice????

Also, in my situation above Is there a better way to kill the engine other than pulling the spark plug wires?

tnplicky wrote: 1995 Ski Nautique GT-40 Pro Boss PMC/Ford 351 EFI Today, engine turned over but would not start at the boat ramp. I suspected the fuel relay since I did not hear it prime. I had messed around with the relay the other day to re-mount it as the replacement relay did not mount the same way as the original.

Tell us more about the relay. You say it didn't mount the same way. What was different?

The original Hella relays have a small metal bracket which snaps in the back of the relay and blots to a bracket on the back of the engine. The new relays (from a different manufacturer from NAPA) did not work with the small Hella bracket. I velcro-ed them in place instead.

It ended up being a bad "new" relay, I believe. I had replaced both relays previously, so I had 2 "old" ones, one bad, one good and the 2 "new" relays. Well apparently one of the "new" relays is now bad. The boat currently works normally with the good "old" and the good "new" relay.

What I didn't understand is why there was power to the relays without the ignition switch on or the key in the on position. Like I said previously, I got it started but then it wouldn't shut off.. I am not good with electrical systems, but something in the relay was allowing the boat to continue to run with no key, ignition switch off, and kill switch removed.

Now with 2 good relays, everything works as it should.

Not sure, like I said am not good with things electrical, but everything should be "original" on the boat. There have been no modifications that would have increased electrical demand.

I am going to order a couple of new Hella relays to have on hand for the next time, if and when it happens.

I am hoping I have taken care of the issue for now.

I am just glad it seems to be working for now.   I appreciate the helpful advice.

Gary S wrote: 8122pbrainard wrote: . I feel it comes down to using cheap instead of going with the NEMA standards. Your being pretty hard on PCM there Pete.I think 20 years in a marine enviroment is pretty good. The NAPA replacement is the one that lasted what weeks? The originals are Hella's,got my spares on Amazon for something like 6-7 dollars each

Gary,
I never said anything about Napa.

I feel part of the high failure rate of these relays is how hot the plate on rear of engine gets. You could fry eggs on it most of the time. So instead of acting as a heatsink for the relays it is more of a heat soak. Insulating and spacing them of the plate with some air gap may help reliability.