Fuel Pump Relay

[Scottvr26]

I have 5.7L 350 Mag Horizon MPI's in my 320 and my port engine has blow 2 fuel pump relay's. This time 1 wire going into the plug is burnt and a fairly simple fix but the question is Why?

Wondering why I am blowing the relay and wondering if anyone else has experienced the same problem.

Thanks,

Scott

 

[tony1b2000]

Can you see the contacts of the relay? If they look fine, you may have a loose connection in the relay socket. If the contacts are completely worn to nothing, it indicates to much amperage and the pump may be going bad by drawing to much power. My gut tells me you have a loose connection on the relay socket.

 

[TARANTULA]

Had the same problem in my 320 (5.7's) I need found the problem now i just carry extras. BTW is always the stb engine.

 

[raffles]

I had the same issue a few years ago. The relay was burnt. The relay was replaced and my mechanic used some dielectric grease on the connection and have not had a reoccurrence since.


I also carry a couple of extra relays on board just in case

 

[Vince_nj1]

I had the same problem. The marina now tells me now that the fuel pump is siezed and I need to replace the entire Cool Fuel Gen 3 unit. Between the first diagnosis of a burnt relay ($270 for labor and $30 for the relay) and the 2nd diagnosis of a bad fuel pump and install the new fuel cooler ($440 labor $1000 for the fuel cooler and hoses) I am out almost $1800. Thank you Mercruiser for your bad design.

Do a search for "Cool Fuel 3" and read about these units. My suspicion is that the paint delamanted inside the unit and clogged the fuel pump which caused an extra heavy load to be place on the electric system which in turn burned out the relay and in my case the the fuel pump.

Read this. I would recommend performing the pressure test outlined here:

http://www.marinemechanic.com/merc/distributors/mercurymarine/sterndrive/gen3fuelmoduletesting.PDF

 

[Scottvr26]

Thank you so much for the info. Guess the question is do you need to replace the whole fuel cooler or just the pump that is causing the issue. I wondering if its the low pressure side or the high pressure side.