Mercury 500 1970 low spark

[midgetme23]

I have a mercury 500 that was running great. Was cleaning the old boat up so decide to clean motor to big mistake run better dirty. Well got to river motor started and run good for bout 30 second v while warming up. Since then I have got it to hit a lick or 2 but will not run drain bowls on carb just in case water got in it. Still nothing. Check the spark with a gauge and I'm only getting about 1/8 spark that is blue some times lite color other times can get a good 7/16 spark coil ohmed out round 50 ohms but it did ohm out any ideals checked coil wire going to dist cleaned all connections when it does hit I got throttle all the way forward when I back it off it dies

 

[midgetme23]

Anybody got any ideals. Could the distributor have water in it causing it

 

[clueless75]

Check the distributor as im not sure about your model but there should be a little carbon lead and spring in the middle. Sometimes those things break causing a weak or no spark. Also, check points in the distributor for corrosion as well as spark plug boots.

 

[midgetme23]

Well I run a straight wire into coil to check for spark there I have a light spark there could the coil be getting weak

 

[CharlieB]

The trigger in the distributor models have a history of dying. The CDI Troubleshooting guide clearly spells out the correct testing method. Follow it to the letter.

Do NOT attempt to remove the rotor. It does not come off, it is part of the shaft assy and very expensive. Be very careful around it.

CDI Troubleshooting-Guide-Inside-Pages.pdf

 

[CamaroMan]

has it had enough time to dry out? water in the plug holes can cause this..

 

[midgetme23]

Put a new coil on it now have no spark. Both coils ohm out the same

 

[midgetme23]

Well I went straight out of coil with wire when motor starts to turn over got decent spark but if I keep turning it over spark is just intermittent. Does the stator have anything to do with it. If switch box was bad I wouldn't even get spark right. I am completely lost

 

[midgetme23]

Nobody has nothing to try. Got 2 triggers order for the distributor not sure they will work but going to replace