Engine sometimes will die

[Brandon5778]

Boat is a 1975 mercruiser 888.

As title states, my engine will sometimes randomly die. When it happens and I try to start it, it will fire back up but then die the second I let the key fall back into the run position. To me out on the water, this indicated something electrical, and I was able to get it going again by unplugging the wiring harness on the engine, blowing it out, and plugging it back in. This has only happened maybe 5 or 6 times in total, and I have got it working again each time quickly by the aforementioned method. Why does this happen? Do I need to replace the entire wiring harness to fix it?

Here is a pic of what I'm talking about. Thanks!

 

[kmarine]

corrosion on a 40 year old connector is probably your issue. Clean all pins and sockets inside with spray can of electric motor cleaner or contact cleaner and tiny wire brush or super small pick. Try to find which wires are affected and as a last resort jump the bad wire with removable blade type electrical connectors. the colors ahould be the same on each side of the plug make sure the jump wires are heavy enough for the wires jumped.

 

[alldodge]

it will fire back up but then die the second I let the key fall back into the run position.

I would test you key switch

 

[Bondo]

Ayuh,.... If the problem is in fact in the cannon plug,.... Take it apart, 'n Clean it,....

Grease or fluid film will stop further corrosion,....

The pins, I believe you'll find are split, so can be tightened by ever so slightly spreadin' the pin's half's,...

 

[Brandon5778]

Yup pretty dirty, but there appears to not be any corrosion at least. I'll clean it.