Mercruiser ignition acting funny....
 

Top of the afternoon to everyone! Hope everyone has a great weekend out on the water!!

Question...

I'm having a strange problem with the starting/ignition circuit on my 383 (Merc Thunderbolt ignition). When I go to start her, she just turns over, but then as soon as I let go of the key (back to run) she fires and starts. I'm thinking that the starter solenoid might be going south (I bought a replacement), but I was wondering if maybe any of you had any insight into what could be going on.

I hope to be out on the Bay this weekend, but I'm hoping to have this solved first because though she does start now, something is on its way out and I'd rather not be stranded.

Thanks!

Re: Mercruiser ignition acting funny....
 

There should be three terminals on the starter solinoid the one furthest from the block should have a wire going to the coil it is a by pass so that while you are cranking the coil still gets enough votage to start the mtr I would check that wire ( some mtrs do not have this )

Re: Mercruiser ignition acting funny....
 

That usually means low voltage at the coil. With the starter cranking the voltage is so low that you are getting very weal or no spark. When you release the key, the voltage jumps up, the spark gets much stronger and if the engine is still rotating fast enough, it may start.

It could be the battery, or a connection somewhere, but I betting if you check the voltage at the positive side of the coil during cranking, it will be low.

Dave

Re: Mercruiser ignition acting funny....
 

dave is right, that is why they used to use the outter terminal on the starter to power coil while cranking it is also used for electric fuel pumps for power before oil press builds enough for the press switch to take over

Re: Mercruiser ignition acting funny....
 

I didn't think of the problem as being a low voltage condition. My starting battery is new/strong so it may be a bad connection that I'll have to diagnose. Fun fun!

Re: Mercruiser ignition acting funny....
 

I would have to agree. Had same problem but with a street bike.

Re: Mercruiser ignition acting funny....
 

Low voltage symptoms.
Check batter, wiring. Also, there's a good chance it could be some corrosion or poor contacts in the ignition switch itself. Had a similar problem, the key witch contacts were old/worn/corroded so much, it would not supply enough current for both solenoid and ignition while cranking.
Gary

Re: Mercruiser ignition acting funny....
 

Yeah, I'm going to clean up all the connections and see how it goes. The salt air really likes to screw with stuff I guess.