Mercruiser 5.0 Mpi electrical issue

[salty3rd]

Gentlemen, I recently purchased a Sea Ray with twin 2002 5.0 Mpi bravo 3's. The steering pins on both transom assemblies needed replacing. Instead of cutting into the transom assembly, I removed both engines and transom assembles to make the repair. After reinstalling and hooking the port engine up, I turned the ignition on, the gauges acted normal but the fuel pump didn't come on and I didn't get the audible tone like normal. The engine will turn over if I go to the start position. I checked the basics, loose connections, etc..The three fuses by the relays were all good however only the middle fuse had 12 volts on it..Any ideas on where to go from here is appreciated..Thanks in advance..

 

[Fun Times]

If the center fuse seems good which in the diagram below suggests it to be for the Main Power Relay via the red/purple wire heading to #30. If the relay is stuck or not connected properly then the relay might not be switching over from 87A to #87 powering up the Red/Black wires which run to the two outer fuses to power up the fuel pump, injectors, coil and coil driver.

If this seems to be the case you could try both tapping on the top of the relays with the key on to free them up internally or switching the two relays around to see if you get some sort of power change in the system as the other relay if for the fuel pump only.

All this is of course that all your ground wires are connected properly which would include one or two small black wires running towards the rear of the engine bell housing studs as those little black wires are for the ECM ground connection which needs to be clean and tight + not damaged during reinstallation, etc..

Make sure the port engine ignition safety lanyard switch is in the on position by physically moving it a few times.


http://ww2.justanswer.com/uploads/thepuddleduck/2010-01-05_103332_ignition_relays.jpg

 

[salty3rd]

Thanks Fun Times for the reply. When I finally got around to looking at the issue I found one of the ECM connections a little loose. All set now.Thanks for that wiring diagram, it will help in the future for sure..