3.0 mercruiser ignition wiring problem.

[putback]

This is an '85 starcraft 3.0 alpha 1. Electricity shuts off after 1 or 2 minutes running. Here's the background. Ran fine, starter was getting weak so I changed it out for new instead of rebuilding. When I removed it I noticed the solenoid stud for the coil was obviously broken off inside, no doubt, could almost pull it out before I touched it with a wrench. Installed the starter, started fine ran well for a couple minutes then shut off. No electricity at all for about a minute, then power comes back on starts fine runs well and shuts off after a minute or two. Do it all day. Just like a circuit breaker. Next step, I disconnect the Purple-Yellow ignition coil wire at the solenoid leaving only electricity to the coil from the Purple wire, problem goes away. As on an older GM car there is only power from the solenoid stud to coil on start. What am I missing?

 

[Bondo]

Ayuh,.... No ignition power,..?? Start at the ignition Switch,....

 

[tlewis1]

Agree with Bondo...When the engine dies check to make sure you still have 12v going through the switch. If not you can jump the wires on the switch to see if the engine will stay running..If it does you've found your culprit.

 

[putback]

That's one of the symptoms. When it shuts off there is no power to the switch on the Bat terminal for about one minute. Then shazam, power restored, every time, no exceptions. The coil has two power sources. Solid purple, a resistor wire from a junction block that also supplies power to the elec choke. When working properly this wire is the primary coil power supply whenever the switch is on. The second wire directly to the coil from the starter solenoid is the purple-yellow stripe wire. It only supplies power to the coil when the starter is engaged. On the original starter that wire was not supplying power due to the broken solenoid stud and I had no running issues. With the new starter and the purple-yellow connected as confirmed by the manual I get the power shut off. If i disconnect that wire No problems. Because of the way it shuts off and restores I'm looking for a breaker tripping & resetting and why. If no one has any other ideas I'll try a new switch. Plausable idea, the switch shorted and that burned off the solenoid stud internally on the old starter.. With the new starter installed I reserected an old problem?

 

[Bt Doctur]

possable causes are loose /corroded battery cable connections at the starter and the block,looses/corroded engine harness plug , bad ign switch

Main power starts at the starter either the red wire is direct or goes thru a 90A link to the starter lug., then to the 50A circuit breaker, then to the harness plug to the dash, and then (maybe) a second harness plug under the dash, then to the ign switch

 

[Scott Danforth]

....and from the ignition switch back thru the one or two plugs back to the motor

Check all your contacts and connections. They all should be shiney and clean enough to eat off of

If you have a sefety lanyard, check that