90 horse Merc won't start

[Tree Farmer]

I have a 91 Mercury 90 horse Electric start outboard i bought used in 2007. i took it to a marina here and had them look it over and give it a tune up. they told me it ran fine and was in good condition. putting it in the water i couldn't get it to start. took it home and parked it. turned the key and it fired right up. back to the lake and it wouldn't start. back to the marina. they hook up the mouse ears and turned the key and it ran just fine. back to the lake it won't run.

i have rebuilt the carbs, replaced the starter solenoid, new plugs. compression is 130 to 135 on all cylinders. have voltage from the stater on red, blue and yellow wires. no voltage to coils. have disconnected the rectifier, no change. new ignition switch yesterday. the battery is fully charge and the starter turns over smooth and fast. i have also cleaned all terminals. gas into carbs makes no difference still no start. it occasionally starts and runs but the next time won't start. when it does start it's after sitting and i haven't made any changes, but then back to a no start condition.

i'm confused on part numbers as the serial number is 0D153xxx and that is a 1993 or newer but all the wiring and parts are off of a 92 or older example is the switch box is a part number 332-7778A1 from a 91 and they look like they belong on this motor. the wiring harness matches a 91 not a 93.

thank you for your help
Tree Farmer

 

[Tree Farmer]

Re: 90 horse Merc won't start

I replaced the stator, trigger and switchbox. it appears to have cured the problem.