Mechanic Question: Choke Wire Question on a 1985 Boat Mercruiser.

[AngryPossum]

Hi, any mechanics with some advice please.
I just installed an electric fuel pump to my 1985 Mercruiser 140hp Inboard Outboard Engine, I removed the mechanical pump and blocked it off with a block off plate.

I'd like to know if I can run the positive power lead from the 12 volt electric fuel pump to the positive lead to the choke wire on the carb, (purple wire).

In what I have read, the voltage may drop to 9 volts on the choke wire. Any advice would be greatly appreciated.

Photo Enclosed below. I'm thinking of tapping to or off that wire connected to the carb choke terminal.

 

[Richard Cranium]

Your first post on a Mopar forum is about a Mercruiser boat engine issue?

 

[AngryPossum]

Your first post on a Mopar forum is about a Mercruiser boat engine issue?


View attachment 1445290

Lmao, yes. I figured there would be some good mechanics on this forum.

 

[AngryPossum]

 

[toolmanmike]

Hi, any mechanics with some advice please.
I just installed an electric fuel pump to my 1985 Mercruiser 140hp Inboard Outboard Engine, I removed the mechanical pump and blocked it off with a block off plate.

I'd like to know if I can run the positive power lead from the 12 volt electric fuel pump to the positive lead to the choke wire on the carb, (purple wire).

In what I have read, the voltage may drop to 9 volts on the choke wire. Any advice would be greatly appreciated.

Photo Enclosed below. I'm thinking of tapping to or off that wire connected to the carb choke terminal.
View attachment 1445284

I would run the choke wire separate. You don't want to overload your fuel pump circuit. I would also suggest some kind of a oil pressure shut off that will kill the pump if the engine stops.

 

[AngryPossum]

Here's the color codes I believe for my harness. I'm not 100% sure. That purple wire seems to be the go to. But I'll check the other options.

 

[mrhemi]

Electric fuel pumps in a boat are a no no, unless the original application was fuel injected, which yours is not. The fuel pump would need to be marine rated and approved as well as the appropriate safety interlocks applied. You should just repair the original pump or replace it in kind, meaning a marine approved fuel pump.
Probably not the answer you wanted to hear, but you asked for experience.

 

[72redbird]

I have a 1995 Maxum with a 4.3 l Mercruiser in it. It is the carbureted version 185 hp. It came with a electric pump from the factory that is connected to the starter solenoid, but it also has a low oil pressure switch that shuts it (the fuel pump) off as a safety. The pump is also a low pressure pump due to being carbureted. Fuel injection engine uses the high pressure pump, they look the same.

 

[mrhemi]

I should have expanded my reply to include OEM installed electric fuel pumps. 72redbird, your example would be a marine rated fuel pump and includes the necessary safety interlocks. Even a mechanical fuel pump on a marine engine is different than it's land based equivalent and should never be replaced by a cheap parts store auto replacement.