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Noel Schembri
Noel Schembri, Marine Technician
Category: Boat
Satisfied Customers: 1954
Experience:  Advanced technical diploma
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I have a customers mercruiser 5.0 catalyst engine with a pcm

Customer Question

I have a customers mercruiser 5.0 catalyst engine with a pcm 09 controller. Engine is out of boat because of a collision that ruined drive. Have engine on stand, hooked up to battery, water, and fuel. Turn ignition key on, main power relay does not turn on, and then of course fuel pump relay wont cycle. Engine will crank normally, but of course will not start. Have checked all fuses, and main circuit breaker. I checked grounds at pcm terminals A4C, C1G, and C2G. Checked for battery power(with main power relay jumpered) at PCM terminals C3G and C3H. Also checked for ignition power at B4G, which should then have pcm send gound control to turn on main power relay. With main power relay jumpered, all 8 fuses are hot, but cannot get pcm to communicate with scanner, and pcm will not cycle fuel pump relay. Had access to new PCM, but had same results. I must be missing either some ground, power, or ignition feed
Submitted: 2 years ago.
Category: Boat
Expert:  Noel Schembri replied 2 years ago.
Hello my name is ***** ***** I will assist you. Check the shift switch on the shift plate where the cables are connected to be in the center position as otherwise it will think that it is in gear. Other from that it seems you are doing everything ok. Noel
Customer: replied 2 years ago.
If it thinks it is in gear, usually that will keep it from engaging the starter, the starter engages as it should, but the pcm does not turn on main power relay, cycle the fuel pump, or communicate with scanner when the key is turned to the run position. To use the normal igniton switch I have used for years on the 454 and 502 efi's, I had to purchase the 14 to 10 pin electrical boat harness adapter, is there more than just the purple wire that needs to be hot when in the run position on ignition switch?
Expert:  Noel Schembri replied 2 years ago.
It should be only that but i do not have the schematics in hand, i will opt out maybe someone else can assist you . Noel
Customer: replied 2 years ago.
okay, thanks anyway!