Starter motor won't disengage only when engine doesn't fire - Need Advice
 

Hi guys,

I have had had this issue for years, but it only surfaces when I have no fuel or no ignition to the engine, ie no firing, and try to start the car.
For example when I had sticking primary injectors, or when my ignitor plug wasn't connected.

Basically when I crank the engine and there is zero firing, the starter motor continues to turn even when I remove the key. The only way to stop it is pull a battery lead.

But then as soon as I fix the no fuel/no ignition issue, and the motor fires internally, the starter disengages perfectly as normal.
So I am assuming the engine's power turning the flywheel disengages the starter motor, but when there is no firing the starter is not disengaging on it's own accord.like it should.

What could be causing this? The car is automatic btw.

Thank guys.

Does the car have an aftermarket car alarm or remote start? Sounds like a problem with one of those doodads. The remote start has a tach input that stops trying to start the car once it sees the tach signal showing the engine is running.

I can't think of any way a stock car would do that.

Dale

Faulty starter solonoid? Engages but does not disengage? Engine running may jar it loose

Dale it's funny you say that, I literally discovered an old alarm/remote start module under my dash on the weekend, but it didn't seem to be fully connected up. There is a newer Mongoose alarm which is connected up and working. I assume the old module was bypassed for the newer one.

So I ended up removing the old module on the weekend to clean up all the under dash wiring.

The same problem with the starter motor staying on is happening, but not only that, now when I pull the earth lead off the battery to stop the starter motor spinning it stops, but when I go to reconnect the earth lead to the battery it's like it's shorting the battery, there are huge sparks and the earth connector starts burning into the battery post, and the engine starts turning over again!

Previously every time I used to pulled the battery lead to stop the starter it would stop, I would wait a few seconds then connect the earth back to the battery as normal and nothing else would happen...

I'm guessing TomU is correct - the solenoid contacts are probably welded together (that would cause the sparking and trying to start again) and not able to separate except when engine starting forces them apart due to the reverse force on the pinion internal spiral. It was probably having a mild version of that issue before, but now it is more severe.

I would still double-check that alarm wiring, sounds like it's a mess. You can unplug the small wire from the starter and hook the battery up - put a meter on it, if it's getting 12v, it's a wiring issue. If not, it could be something with the solenoid.

Dale

I actually pulled the small wire off the starter solenoid, then tried to connect the earth lead to the battery and it still sparked like crazy and started burning the post. I then waited about 10 minutes and tried again and then there was no spark and I could connect the earth to the battery as normal...

Maybe when it cooled off, the solenoid contacts separated - some sort of thermal expansion issue making them stuck in the closed position. If you didn't hear a "click" from the solenoid moving when it sparked and turned the engine over, the solenoid contacts likely were stuck together - if the solenoid had to move to contact there should have been a "click" sound.