Starter Cutting Off/On

[pwgsx]

I am working on a 98 gsx limited. The owner didnt secure the battery and it shorted out melting the posts and apparently killed the starter as well. He replaced the starter solenoid hoping that was the issue but no luck. He didnt want to mess with it so I took on the job, dropped the carbs and swapped the starter. Now when you press the start button it cranks the engine for a second, then the starter seems to just pause, then it kicks back on, then off, then on. Sometimes after this on/off cycle a few times it stays on then it cuts off again. Any ideas? Im thinking the solenoid he put in is possibly bad OR he fried his mpem??

 

[tobytd]

Test battery

 

[Ckrawiec]

I am working on a 98 gsx limited. The owner didnt secure the battery and it shorted out melting the posts and apparently killed the starter as well. He replaced the starter solenoid hoping that was the issue but no luck. He didnt want to mess with it so I took on the job, dropped the carbs and swapped the starter. Now when you press the start button it cranks the engine for a second, then the starter seems to just pause, then it kicks back on, then off, then on. Sometimes after this on/off cycle a few times it stays on then it cuts off again. Any ideas? Im thinking the solenoid he put in is possibly bad OR he fried his mpem??

Simple test.....jump the solenoid posts....this applies battery power directly to the starter.....the starter should crank the engine (remove the spark plugs to remove the compressive load off the engine). If the starter cranks strongly, then start working backwards from there.

PS: While you are there...what's the compression in the cylinders like? Test that as well.....no sense wasting a lot of time on an engine that may be past it.....you are looking for near 150 psi in each cylinder with no more than a couple psi difference between the two....that's just a quick engine health check.....NO Harbor Freight guages though....borrow from AutoZone if necessary.

 

[pwgsx]

New battery, New solenoid, New Starter ( old one was fried ). If I jump the solenoid it cranks fine all day long. IF I use the start button its 2 second bursts. Did I get a bad "new" solenoid or is the MPEM shot from the battery shorting out?

 

[Ckrawiec]

New battery, New solenoid, New Starter ( old one was fried ). If I jump the solenoid it cranks fine all day long. IF I use the start button its 2 second bursts. Did I get a bad "new" solenoid or is the MPEM shot from the battery shorting out?

According to your wiring diagram.....the Yellow/red wire to the solenoid is the "trigger", that wire is pin 3/16 from the mpem. Can you put a multimeter on that wire and see if you are getting a signal. I'd also check all my connections at this point.....corrosion is an insidious thing and will drive you up a wall chasing electrical issues (been there).

 

[pwgsx]

MPEM ended up being fried. Got another and its back up and running! Thanks for the help