1987 OMC Cobra 4.3L won't shut off

[richwilliams]

I have a 1987 Four Winns with a new alternator and the ignition switch is fine but when I shut the key off the engine continues to run until I disconnect the alternator.

 

[Don S]

Re: 1987 OMC Cobra 4.3L won't shut off

NEVER disconnect the alternators main POSITIVE B+ wire with the engine running.

Now, what wire did you disconnect from the alternator. Is this the same type alternator you took off? Is it wired properly?

 

[richwilliams]

Re: 1987 OMC Cobra 4.3L won't shut off

No it's not the same alternator and I disconnect the brown wire from the alternator not the main power wire.

 

[Don S]

Re: 1987 OMC Cobra 4.3L won't shut off

If it's not the same kind of alternator, then it is probably wired different. Whithout knowing what alternator you now have, no way of answering how to wire it correctly.

 

[richwilliams]

Re: 1987 OMC Cobra 4.3L won't shut off

Went from original equipment to a stock GM non-marine alternator.

 

[HT32BSX115]

Re: 1987 OMC Cobra 4.3L won't shut off

Well,

There's probably 10 people getting ready to say this.....

You need to pull that alternator and replace it with a MARINE unit.

If you run it that way you will put yourself and any passengers at great risk. (and your insurance company may refuse to pay if they find out you used an automotive alt in your boat when it blew up......and believe me they'll check and so will the passengers lawyer during the lawsuit)

In the meantime, Keep the fire extinguisher handy, wear a PFD and be ready to jump





Ok, you have a wiring error also. Your coil is getting power independently from the alternator with the key off....... otherwise it would shut down correctly.... (unless you're dieseling, then it's a different problem......)

If you don't have a manual for that engine/drive, you need to get one. It needs to be an OEM OMC manual for an 87 Cobra. (I just sold one recently along with a Drive etc....I know this doesn't help but I bought it on Ebay for about $100. It was a reprint)


Good luck!


Rick