Mercruiser 502 Mpi Starter Problems
 

Hi all,
I went to dip my boat last weekend and she wouldn't turn over. I've had some battery problems so I went ahead and changed the batteries to only find it helped with nothing!

My starter doesn't even turn over, all I hear is a clicking noise from a relay board on the top port side of the motor. I put a screwdriver to the starter and it turned then but the motor still did nothing.

Any ideas?

bad ground....

Make sure the exhaust manifolds have not leaked into a cylinder and hydraulically locked the motor first. Do that by pulling the spark plugs and trying to start the motor. Look for water coming from the plug holes.

If the motor won't turn over with the plugs out, find the slave solenoid that is making the clicking noise on the motor and jumper it on the big poles with a big wire. The starter should turn the motor over. Then you can replace the slave solenoid.

Last look at the starter. You said the starter turned but the motor did not?

Check ( push ) the red breaker to see if its popped.

There is a solonoid at the back of the motor,,,, check for 12 v at the larger studs,,, 12 volt key on one one side,,, ket to start it should transfer to the other side.

Then check the triiger wire ( small purple wire ),,, if nothing at the small wire check ( wiggle ) the main harness.

I'll give it a shot - hopefully it's not the case. She hasn't been ran in over 4 months.

You need a new starter relay. It is under your mpi bracket. They are from 12-25.00. I have had to replace mine a couple of times. I keep a spare on board for emergancies.

Never use an automotive relay. They look the same but they're not. It'll either last two weeks before the moisture gets to it or if you're really "lucky", it will ignite the fumes in your bilge.

pull the sparkplugs and check for water before it takes the teeth off the flywheel, with the small high torque starters, all it takes is a few good hits in the same spot on a locked up motor, use a test light and follow the power from the slave solinoid to the starter, its a yellow with red tracer wire.
Larry

Thanks for all your help but I think I may have bigger problems than I thought. I went to pull the spark plugs and they are rusted in. I'm assuming there was a leak in the exhaust and it just leaked down. I'm confused becasue my boat always ran so strong and I layed off it for a few months and now all this. If the motor is locked up is it a costly fix? Thanks again for all the input.

MobbinMinis,

same thing happened to me, didn't start the boat for a month or so, when i had it checked by a mechanic, he stated it was the starter motor, 3 months later when he finally got starter he says the block is seized due to reversion. now i'm sitting to dry docks trying to decide what is my next move. oh well!
sorry to hear though

If your cylinders filled with water, you'll probably have to do a partial rebuild. If it's not too bad, you may be able to get away with a bore and new pistons. If your motor has some hours on it, I'd have the rods rebuilt and the crank ground. New cam too.