Mercarb wiring question?

[dsims]

I bought a 15 foot ski boat last year and rebuilt the carb at the end of summer. Well after rebuild I let it sit in garage covered. Now that I am putting it back on I have an embarassing problem. I cannot get the fuel pump to come on to pump fuel. There is a wire that goes from the fuel pump on top of gas tank to what looks like the carb because thats how long the wire is and it is a black wire. There is also on top on other side of carb closest to the oil filler cap 2 black wires that look like they should go to the carb or somewhere close. The only wire I am sure of is the electric choke wire. I have a mercruiser 120 motor. Does anyone have a pic of the fuel pump wire or the top of the motor to tell where these wires go? Thank you in advance everyone.

 

[Don S]

Re: Mercarb wiring question?

I cannot get the fuel pump to come on to pump fuel.

That is because you have a mechanical fuel pump, not an electric one. The only way it will work is when the engine is cranking over.<br /><br />If you actually have a fuel pump on top of the fuel tank, it's probably not marine and definatly not safe. <br /><br />You also shouldn't have any wiring going from the center of the fuel tank to the carb.<br /><br />I would suggest you take your boat to a certified Mercruiser dealer and get it looked at. Maybe not fixed, but at least evaluated.<br /><br />The next step would be to get a Merc service manual for your engine, whatever year it is, and do some reading before you even start trying to fix things.

 

[Bondo]

Re: Mercarb wiring question?

Well,...... Boats Don't have Fuel Pumps located In the tank..........<br />There's a Pretty Good Chance that None of the Wires you mention even have Anything to do with the Carb............<br /><br />So,......<br />Without ALOT more Info,........ I Doubt anybody is going to be Able to Help you..........

 

[dsims]

Re: Mercarb wiring question?

I rebuilt the carb last year after the accelerator pump went out. I think that the wire coming from the tank maybe a sending unit then and the wire is a ground. Now the other two wires are loose on the other side and they have round terminals on them. When I took the carb off last year I know that I would not just take the wires loose unless I had to to pull the carb off. I am thinking they go under the screws that hold carb top to base as just grounds. I am sorry I didnt know about the fuel pump being mechanical. So now that I have it back on if I understand you right I just need to try cranking it and as I do that it will add fuel to the carb?

 

[ron7000]

Re: Mercarb wiring question?

yeah,<br />you didn't mention the year of the boat or motor, unless the previous owner did something you have a mechanical fuel pump. The wires coming out of the fuel tank are for your gas gauge on your dash. One wire will be a ground and the other will go to the back of the gas gauge.<br />These wires won't matter in starting the engine, since you had the carb off you will have to crank it a while to refill the carb with fuel before it starts, and longer if you had to remove fuel lines going to the carb and any (large) fuel filters.<br />What I will do is have the fuel line at the carb disconnected and going into a can and crank the motor till I get fuel so I know I got fuel, then hook it back up to the carb and crank it for 5-10 seconds and it'll start.

 

[dsims]

Re: Mercarb wiring question?

Thanks Ron it is an 87 with the 2.5 mercruiser motor. That is what I wanted to make sure of that I was getting fuel to the carb and I will try your way. I wasnt familiar with marine fuel pump and didnt know they had mechanical fuel pumps. Now I am understanding how it works. I just wonder what the two wires are that are close to the choke on the carb. I know they dont go to the choke cause I have a purple wire that goes to it but they are just close to the choke coming out of some wire loom. I followed them and they go down to the circuit breaker and another small thing bellow the breaker.

 

[kcole683]

Re: Mercarb wiring question?

Probably a ground wire that goes under a screw on the choke housing.<br /> It seems that my mercarb has a wire plugged into the choke heater and a couple of wires with ring terminals on them under one of the choke housing screws.