90 Merc 90hp, can only start by jumping starter with screwdriver..??

[bigvinnie]

Was starting fine with ignition switch previously... shut it down for a while and then turned the key to start, and nothing, starter does not respond... starts ok by jumping the solenoid terminals with a screwdriver. So I figure it's either the solenoid or the ignition switch...

Suspecting the solenoid, but would appreciate suggestions for a test procedure to isolate the cause...

thanks in advance for the help.

 

[Silvertip]

Re: 90 Merc 90hp, can only start by jumping starter with screwdriver..??

You would be wrong on both guesses. If you checked the fuse under the engine cover and found it ok, then perhaps one might go with your guesses. Using a voltmeter or test light, check for voltage on the small "S" terminal on the starter solenoid which someone turns the key to START. No voltage = wire harness, fuse, or bad ignition switch. Voltage present = switch and harness ok. Solenoid probably bad. If you are jumping the two large terminals you are bypassing the solenoid. If you are jumping from the red battery cable to the small "S" terminal then that says the solenoid is OK.