No power fuel pump

[Baldy177]

Hello to whoever reads this. I have a question about the main power relay and the other main power relay that mounts under the ECM. ITS A 2003 Mercury 150efi. I removed and had cleaned the injectors, after putting back together fired it up and it sounded great, after about ten seconds it died. I later found out the electric fuel pump went out but also had no power going to the fuel pump. Checked the relays and they work fine, but had no power to the fused relays. I’ve tried everything to find out a way that the fused relay gets power and the relay switch doesn’t work when I turn the key on. If anyone has any suggestions please respond, thank you in advance for any help

 

[alldodge]

Not an OB guy but being its a Mercury the wiring should be the similar to a Mercruiser. Power is present all the time at the main power relay (MPR) fuse and fuel pump (FP) relay fuse. The fuse passes voltage to one side of the relays.

When power is applied to the ECM by the turning on the key, the ECM will connect a ground to the other side of MPR and FP relays. The ground turns on the relays on and then power is connected to fuel pump and the motors system.

Since it was working and then stopped, look for something which has become disconnected. Also check the kill switch that even though it appears to be on, it may not be passing voltage.

 

[Baldy177]

Thank you for your help, do you think the ECM is fried? I’ve looked for days trying to find something broke or disconnected and can’t find a thing.

 

[Baldy177]

Is it a possibility that the key switch went bad?

 

[alldodge]

I doubt the ECM is bad and there might be an issue with the key. Need to use a voltmeter and track where your loosing power. My guess is its something simple because it just happened, hard part is finding it