1980 V4 electrical fault

[sly_karma]

I bought a project boat with a 1980 J140MLCS on it. The engine has 110 psi on all 4 and will start fine - but the only way to keep it running is to hold the key in the 'start' position. I have a factory service manual and went through the continuity tests for the ignition switch and starter solenoid; both checked out correctly. Clearly I have some kind of electrical discontinuity but I've reached the limits of my own abilities. Before I drop it off at the shop at the busiest time of the year, has anyone seen this before?

 

[woody66912]

Re: 1980 V4 electrical fault

Disconnect the big red plug on the engine side. Jump the starter solenoid from the 12 volt side and the yellow / red, if the engine stays running then your main engine harness is at fault.

 

[emdsapmgr]

Re: 1980 V4 electrical fault

woody has recommended a good test. If you find the harness is the problem, look at the key switch first. When the key is in the "off" position, the black wire with the yellow tracer grounds out the two power packs-killing the engine's ignition.

 

[sly_karma]

Re: 1980 V4 electrical fault

OK, I'll try shorting from the harness plug when I get back to town this weekend. According to the service manual tests, everything is functioning correctly in the key switch. The 20A fuse off the starter solenoid is intact and there is continuity right back to the switch. Thanks for the replies.