I have a 85HP Mercury Boat Motor. The motor will not turn over at all.?

Question

I had a got a new battery so I know it is getting enough juice, but it still will not turn over. I do not think it is seized up becasue when I jumped it off the starter it tried to turn over. Any suggestions would be greatly appreciated.

Answer 1

You should first verify that the motor is not seized by removing all of the spark plugs and turning the flywheel by hand. If it turns easily, next make sure all of the battery cable connections are cleaned and tightly secured to their connectors on BOTH ends.  If that doesn't fix the problem, you probably have a bad solenoid or starter.

Answer 2

If it turns when you jump directly to the starter, but not through the normal wiring harness, there is a problem in the ignition circuit.  It could be as simple as a loose cable/corroded cable connections, or it could be a bad starter relay/solenoid.

The ignition circuit (where you turn the key) is a low amp circuit; the igniton circuit activates a relay or solenoid that can handle the high amp draw of the starter.  

Some starters have the solenoid built in, and some are separate.  If the starter has one or two really big terminal posts and nothing else, then the relay is somewhere else in the circuit.  Follow the positive starter cable back until it reaches the relay; it should be about the size of a computer mouse.  Two big terminals will handle the starter circuit, and one or two much smaller terminals will go to the ignition circuit.  If the starter has the smaller terminals, then the solenoid is built in.

A little bit of troubleshooting should determine what the problem is.  Sometimes, LIGHTLY TAPPING the solenoid with a hammer will fix the problem, if the relay inside is sticking; this is more prevelant in boats than cars, for obvious reasons.  If tapping the solenoid fixes the problem, then make sure you replace it; the problem will only get worse with time.

Answer 3

take the plugs out my be stuck on a compression stroke...spray some lubricant in  let set .....then turn over without the plugs in it .....then if it turns over put plug back in it...if that dont work check to see if flex plate a.k.a fly wheel is connected or broken ...