1972 402 40 HP Mercury again

[buddhapi]

here we go again. this thing ran like a top a couple months ago....I sold it, and now it'll only idle good. I can quick rev up to high RPM, but then it'll cut out like there's a rev limiter gone bad. you can't run it up to any useable RPM position like off idle or higher. this thing ran like new, then I removed it from my boat, and laid it on it's side for about 2 months. I sold it, and the guy said it never ran good the second he put it on his boat. I removed and cleaned the carb today, and found nothing wrong. I also fixed a couple cracked- coated wires, and even tried a different fuel line, bulb and fitting on the motor. I'm at my whits end. is there a capacitor somewhere that may be bad? could I be having an issue with the mercury switch, that's partially grounding and still allowing the motor to start? any and all help is appreciated. thank's; Greg

 

[buddhapi]

Re: 1972 402 40 HP Mercury again

Bump!

 

[achris]

Re: 1972 402 40 HP Mercury again

Bump!

Patience grasshopper.... (It's gone midnight in most of the good ole US of A. )

You laid it on its side.... Which side? (I'm betting it was the starboard side....)

Have you done a compression test? Sounds like water may have drained from the exhaust covers and into the cylinders and rusted the bores or rings....

Chris........

 

[buddhapi]

Re: 1972 402 40 HP Mercury again

thank's for the reply...all are welcomed. I laid it down on the port side, where the cables would hook up. so that would be exhaust cover down? could something have got into the exhaust baffle plate...maybe carbon particles?
I was also wondering if it could be water in the fuel. it has good compression in both cylinders, and good spark. I've cleaned the carb again and come across nothing. thank's for any other idea; Greg

 

[buddhapi]

Re: 1972 402 40 HP Mercury again

Bump!

 

[achris]

Re: 1972 402 40 HP Mercury again

Check that all the linkages are moving, that the spark advance arm is moving to maximum spark...

Chris.....

 

[buddhapi]

Re: 1972 402 40 HP Mercury again

thank's for the reply. the cables move fine, as does the linkage rod that advances the timing. I found today that tipping my Mercury switch doesn't kill the motor. my stator/charging unit doesn't work, and the rectifier readings are bad. this motor fires right up and idles, but I can't get any RPM unless I just floor it, but then bogs down a couple seconds later. it's not fuel..if I spray carb cleaner into the carb,it chokes the motor out. this motor has a miss to it like bad contact points or bad condenser, but it's electronic ignition. 1972 402 2 cylinder 40 Horse Mercury. would a bad rectifier or stator give me a motor that starts great, but give me bad voltage readings off idle? is there a chart online somewhere that would give me OHMS and Voltage readings to look for, throughout the entire electrical system?