Motor Starts but won't shut off

[JBRJ65]

Thanks in advance for any advice provided.

72-73 Mercruz 120, sn # 3377984 it's a GM. it's in a 91 Glassstream as a replacement for a 3.0L that the previous owner failed to properly winterize. I did not do the swap and have used the boat for two seasons without issues.
Starts just fine but won't shut off.
I have replaced the ignition switch and starter relay solinoid. Anything is possible with swaping wires by accident and if this happened it was on the ignition switch.
Please check my work on this three prong ignition switch. RED wire to "B" ; PURPLE wire to "I" and YELLOW w/ red runner to "S". If have have this right then please advise if you have another idea of what the issue could possibly be. I don't have an issue replacing the coil or Starter solinoid but can't figure where that would be the problem as it starts and runs perfect. Then again I don't claim to be the smartest fellow. I have a service manual #1 but it doest match the set-up.

 

[dubs283]

Re: Motor Starts but won't shut off

sound like you got the wiring for the switch correct

but is the switch bad?? - dunno

with the key off, check voltage at the purple wire (I post) on the helm switch, you should have zero volts

if zero volts with the key off and you still have the issue, the problem is towards the engine

replacing the slave solenoid would not affect the ignition circuit

 

[Bt Doctur]

Re: Motor Starts but won't shut off

what type of alt and how many wires

 

[JBRJ65]

Re: Motor Starts but won't shut off

I will check once the sun returns to the sky and let you know . Thanks and I will get back to you.

 

[JBRJ65]

Re: Motor Starts but won't shut off

dubs283,
Checked voltage at purple (I post) only got a slight reading (90mV) in the off position and 11.56V when in run position. got 11.56V at Red (B post) and then again on (S post) when cranking. Checked switch off boat for continuity again in the off, run, and start positions and all checks out. ???? I'm stumped

 

[Don S]

Re: Motor Starts but won't shut off

Check that the battery cable attached to the starter is not touching the small terminal on the solenoid.

Still need to know what alternator, and maybe a picture of the wiring to it.

 

[JBRJ65]

Re: Motor Starts but won't shut off

Bt Doctur,

The alternator has 4 wires. Large Black to engine ground / wire harness. Large Orange to Starter solinoid. small Pink or violet (old wire) to wire harness. and a smaller Red that runs into a junction (main breaker / starter relay solinoid / wire harness).

As stated before this is a repower moter that replaced a Merc 3.0L due to winterization block failure and I didn't do the swap. I have used the boat for 2 season with issues. The Red lead and Black lead have both been spliced in but the splices look good and are properly insulated.

 

[JBRJ65]

Re: Motor Starts but won't shut off

Don S,

Already check that connection and the others to insure they are all clean and nothing is touching / grounding.

Question though???? I had a tough time starting motor on water at night last season. Opened cowl and had buddy crank engine and had a light show down by starter. The boat started and we made haste to the dock. Once there we had the same problem with itnot shutting off. I killed it using the interupter switch. Next moring a check revealed the face of the starter solinoid had cracked wide open. I visited my local NAPA and purchased a new statrter solinoid (a marine one) and once installed the problem was fixed. No sparks and it shut down when switched off. Is it possible in some way that the solinoid has gone bad and I need to replace again ?? I looks fine but looks can be deceptive for sure

Help Help its Friday on Memorial Day Weekend LOL Thanks

 

[JBRJ65]

Re: Motor Starts but won't shut off

The alternator has 4 wires. Large Black to engine ground / wire harness. Large Orange to Starter solinoid. small Pink or violet (old wire) to wire harness. and a smaller Red that runs into a junction (main breaker / starter relay solinoid / wire harness).

 

[Don S]

Re: Motor Starts but won't shut off

The alternator has 4 wires. Large Black to engine ground / wire harness. Large Orange to Starter solinoid. small Pink or violet (old wire) to wire harness. and a smaller Red that runs into a junction (main breaker / starter relay solinoid / wire harness).

Yes, you already posted that, but it doesn't tell us what kind or what wire is where. Can you post a picture of it please.

 

[JBRJ65]

Re: Motor Starts but won't shut off

PIC'S AS REQUESTED. That is provided I did it correctly

 

[JBRJ65]

Re: Motor Starts but won't shut off

Yes, you already posted that, but it doesn't tell us what kind or what wire is where. Can you post a picture of it please.

Posted the Pic's as requested

 

[Don S]

Re: Motor Starts but won't shut off

Remove the purple yellow wire off the starter solenoid and see if that lets it shut off.

If that doesn't fix it, disconnect both small wires on the alternator. Leave the orange and the black wires attached.

 

[JBRJ65]

Re: Motor Starts but won't shut off

If puprle yellow doesnt work and I disconnect wires on alternator would I re-attach the purple yellow back again prior to trying ?

 

[Don S]

Re: Motor Starts but won't shut off

Go ahead and re-attach it. That test is just to eliminate the solenoid as the problem.

 

[JBRJ65]

Re: Motor Starts but won't shut off

Don S,

disconnected the battery and removed purple/yellow from solenoid. Boat would not start and didn't appear to be getting any fire. Reconnected the wire and attempted to start again and it fired but wouldnt stay started.
This is new as prior to this procedure it fired and ran on first turn.

Starter solinoid???

 

[Don S]

Re: Motor Starts but won't shut off

Is your lanyard kill switch hooked up?

 

[JBRJ65]

Re: Motor Starts but won't shut off

Yes it is and I double checked the connections as a precaution. It was also replaced but only as a cosmetic issue. The previous would not turn off issue wasnt caused by it as I actually had it hanging down and both pull the kill lanyard as a test and also removed a wire to insure that wasnt the problem

 

[Don S]

Re: Motor Starts but won't shut off

Can I assume you have a points type ignition system?

 

[JBRJ65]

Re: Motor Starts but won't shut off

Yes you certainly can.