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Dominick, Marine Mechanic
Category: Boat
Satisfied Customers: 1009
Experience:  25 Years Experience as Mechanic, 20 Yrs Boat Yard Owner/Mechanic, Factory Certified
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I have a 2010 or so mercury 40hp 4stroke efi. Fuel pump not

Customer Question

I have a 2010 or so mercury 40hp 4stroke efi. Fuel pump not energizing, I figured out there is no ground going to it. Also just realized there is no spark (assuming no ground for it too) Trying to find a diagram of the main harness. Starter is grounded, and trim and tilt are working which makes me think it mnay be a ground issue in the main harness.
Submitted: 1 month ago.
Category: Boat
Expert:  Jason replied 1 month ago.

Hello my name is ***** ***** am I speaking with?

All Mercurys are cataloged by serial number, can I start by getting that number so I know what you have.

Customer: replied 1 month ago.
This is john, serial number is1c131345
Customer: replied 1 month ago.
40elpt bf maybe that's the one you wanted\
Expert:  Jason replied 1 month ago.

Hi John, got it.

Did you need help troubleshooting the issue or did you just need a wiring diagram?

Customer: replied 1 month ago.
Well both possibly
Customer: replied 1 month ago.
I've got a pretty good handle on what I'm doing, but not an expert. I'm actually a Harley Davidson master tech.
Expert:  Jason replied 1 month ago.

What's the story on the engine, when did it last run?

Customer: replied 1 month ago.
Was running earlier this season, the way I understand it, they just came out one day and it wouldn't start.
Customer: replied 1 month ago.
I thought the fuel pump was bad beause I couldn't hear it energizing, and it had power going to it
Expert:  Jason replied 1 month ago.

Is the emergency stop switch clip in place?

Customer: replied 1 month ago.
Customer: replied 1 month ago.
there is no ground getting to the fuel pump
Customer: replied 1 month ago.
i'm guessing the coils as well. however the tilt/trim and starter are grounded
Customer: replied 1 month ago.
fuel pump gets its ground from the ecm
Expert:  Jason replied 1 month ago.

Wiring diagrams and service manuals I have. But I'm not going to be able to help you actually troubleshoot this. The ECM provides the grounds on the circuit, if the ECM is not grounding out the fuel pump, then either you have a bad ECM or a bad sensor on the engine not telling the ECM to turn on. Either way it would have to go into the dealer to be hooked up to a scan tool.

Customer: replied 1 month ago.
I don't think that'll be necessary, but thanks for trying.
Expert:  Jason replied 1 month ago.

You bet, good luck.

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