12v power to elec fuel pump?

[fsjcowboy]

I recently bought a 1996 Wellcraft with a carburated 4.3 Mercruiser. I have not yet purchased a factory service manual for this boat so I'm a bit short of tech data and wiring diagrams.

I am not getting any power to my elec. fuel pump. Pump runs when connected straight to battery, the ground wire to the pump checks good continuity, just no power in the purple/w yellow stripe wire. Is this wire connected to the starter solenoid? Thanks for any help until I get my manual.

 

[Haut Medoc]

Re: 12v power to elec fuel pump?

It is most likely the oil pressure switch that has gone bad....
It is a safety feature that kills the power to the fuel pump when oil pressure is low....
Or the switch goes bad.....

 

[Haut Medoc]

Re: 12v power to elec fuel pump?

Don S

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Re: fuel pump relay
You get power to the fuel pump 2 ways. When the starter is engaged, power to the pump is provided thru the starter solenoid. See drawing below.
Once you let off the key, you have no power till the oil pressure builds up to 3 to 5 psi, then the oil pressure switch closes and the power goes to the pump.

If you are expecting to hear the pump come on when you turn the key to the run position, it's not going to happen.

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Don S. ​

This should help.....
Welcome to iboats, btw......

 

[fsjcowboy]

Re: 12v power to elec fuel pump?

Guys and girls.....please disregard my post...I got caught up so much in continuity, voltage checks, grounds, shorts, etc., I didn't look at the simplest and most obvious.....my lanyard to the kill-switch on the dash was not attached to the kil- switch. Once again.....look for the obvious. thanks for the quick reply.

 

[Bigdave196]

Re: 12v power to elec fuel pump?

X2 on the oil pressure switch. Also check the connection to make sure the wire is making a connection and not just looking like its.

Stupid question, Have you checked the fuze panel to make sure that you have not thrown a circut breaker/fuze? Some times we over look the simple things expecting it to be rocket science. AKA Boat wont start.....fuel tank is empty even tho gage says 1/2 full. Catch my drift.

Worst case is that your fuel pump doesnt like you, lol!!!

 

[Diggerpine]

Re: 12v power to elec fuel pump?

Guys and girls.....please disregard my post...I got caught up so much in continuity, voltage checks, grounds, shorts, etc., I didn't look at the simplest and most obvious.....my lanyard to the kill-switch on the dash was not attached to the kil- switch. Once again.....look for the obvious. thanks for the quick reply.

I've never done that before!!!....But,in all truth, It's happened more than once!:redface: Glad you found your problem solved!

 

[Maclin]

Re: 12v power to elec fuel pump?

Fsj,

You will still not see any voltage at the pump even after the kill switch is in unless the engine is cranking or the engine has started and oil pressure has begun to build. You will not see any voltage with just the key on and engine not started/running.