1994 454 Merc EFI cuts out for a second only in the water

"I bought this boat last summe

"I bought this boat last summer, was running great. I decided one morning to clean the engine area. That day on the lake it started runnig real bad. Took it home, took off the distributor cap, was green, replaced it and ran great on the trailer. In the water however, it cuts out for a second and then comes right back. The more rpm, the more it does it, low rpm it runs fine. Hit a wave, cuts out. Turn back and forth, cuts out. It's like you turn the key off and then right back on. Put it on the trailer, runs perfect. It has the fuel system that has both a sea pump and an electric fuel pump. The real proplem is my wife didn't want me to buy this boat, help me!"

"Richard...

Welcome..

We

"Richard...

Welcome..

We hear you about the wife. Try to get something fun for the whole family to do and .....

Sounds at first like you have a wire thats grounding out and shutting things off, or loosing contact with what it supposed to be touching. The more vibration, the more that loose wire is shaking around and touching something it shouldn't be or breaking contact. How did you clean the engine area? Is there a chance that you pushed up against anything and slightly pulled a wire out of a wire harness connector and now it makes intermitent contact with what its connected to? Maybe you pulled a connector apart a little?
Snoop around and gently pull/wiggle on wires and see if anything obvious shows up.

Wrench"

"Thank You Wrench for your inp

"Thank You Wrench for your input. When this problem first started, I had no dought that it was electrical, because of the how quick it would stop and restart and hitting a wave making it do it also. I have changed my mind. I think it is fuel, I think. Other than the bumps, it is power related. Even if the water is glass, the more throtle, the more of the problem. If I open the throttle, it will never plain off, I have to do it slowly. Once I get it going, I can run at about 3500 rpm. This being said, why does banging it around make it worse? This is my first EFI boat, when it was running I loved it. Give me points and a carb, I can fix it. I did buy a service manual to try to figure out what makes this thing tick, but my knoledge is limited. I did have a thought that there wasn,t enough gas in the electric fuel pump tank, supplied by the sea pump. I just dodn,t know. Thanks again for your reply, maybe this added info will spark another idea, or maybe I need to go back to my first idea."

"Richard
I think you're g

"Richard
I think you're going to have to try the process of elimination. I'm with Wrench, I'd be looking at ignition first off. After checking all the connections on the engine, (where the action of cleaning started it),I would go after the pickup coil in the distributor first. Where the two wires join it gently pull on them and see if the plastic covering begins to stretch, if so the wire inside is broken. Then the dist cap and then the coil.
Let us know. (I like to know when I'm wrong)
Bert"

"Without going thru the experi

"Without going thru the experience, it is somewhat difficult to disect this problem. No promises, just thoughts...

Some other events recall that a failing battery can play havoc with fuel injected engines. Borderline voltage can cause injectors to kick out. Take into consideration the age of battery and test it thoroughly. Make sure alternator belt is tight so it is getting full charge. And perhaps it is in order to test the alternator itself. Failing alternators can disrupt circuits intermittently.
Low overall voltage can also restrict engine/boat speed. Believe me, I have had all these problems at one time or another."