Bad rectifier or stator??

[Bimmerdad97]

I’ve been tracking down issues with a 1985 j150tlcos I’m getting fuel pressure up to 5 psi with engine running. I think I’m getting weak spark due to the engine not wanting to fire at first, then letting it idle for about 30 minutes before it starts acting right. It’s also not charging the battery underway, But I’m not sure if it’s supposed to or not. It only runs right after letting it idle for a while.

 

[saltchuckmatt]

What steps were performed to know it's not charging the battery?

 

[Bimmerdad97]

What steps were performed to know it's not charging the battery?

I hooked my multimeter up to a ground on the engine and to the positive side of the battery cable unhooked from the battery and it’s not charging the battery

 

[Bimmerdad97]

I hooked my multimeter up to a ground on the engine and to the positive side of the battery cable unhooked from the battery and it’s not charging the battery

It also will not stay running long enough to really know and I’m assuming it’s a weak spark due to the stater or rectifier being bad

 

[racerone]

Guessing does get expensive.----These parts can be tested.----You should not be running the engine with battery disconnected.----Might as well test stator windings for battery charging and replace rectifier / regulator.----Does spark jump a gap of 3/8" pm all leads?----Be a good idea to post compression test readings here as well.-----There were issues with broken piston rings on these motors.----Might be the reason for running issues.

 

[saltchuckmatt]

Agree with above. Do an ohm test to the rectifier....it could be toast now.

At idle not much voltage is made.

 

[Bimmerdad97]

Guessing does get expensive.----These parts can be tested.----You should not be running the engine with battery disconnected.----Might as well test stator windings for battery charging and replace rectifier / regulator.----Does spark jump a gap of 3/8" pm all leads?----Be a good idea to post compression test readings here as well.-----There were issues with broken piston rings on these motors.----Might be the reason for running issues.

 

[Bimmerdad97]

I have not checked spark gap and compression is 115 to 120 across all cylinders

 

[cyclops222]

The long idle is SLOWLY warming up the motor. Check if the choke is operating when cold.

 

[racerone]

Choke / primer valve is manually operated.----No automatic choke.----If motor takes long to warm up then , check thermostats.

 

[cyclops222]

My old 1986 Evinrude WILL toss the thermostat flat rubber washer around. So much that the thermostat is held open. Cold running engines is the result. I cured that very long problem by Cleaning the washer side of the thermostat and the surface of the washer. Then lightly and NEATLY applied RTV to both surfaces. Pressed together. Allowed to set up overnight. Cut away any squeezed out RTV. Assembled into engine. . Has hundreds of trouble free warmups.