Mercury 7.5 hp Not Firing

[Oil gypsy]

Hello,

Ive just rebuilt a 1979 Mercury 7.5 two stroke. The engine needed to be rebuilt as the reed valves and oil seals were not sealing.

Im having trouble getting the engine to fire up, the stator can only be installed one way, the flywheel only fits on the shaft in one position due to the woodruff key, there is no fine adjustment. The carb has been stripped down and seems to be working fine.

The resistance on the coils is within spec but towards the low end. I have good compression, both engines have spark but will not fire.

Any suggestions on what could be wrong would be greatly appreciated

 

[racerone]

Switch the plug wires as a test.

 

[Oil gypsy]

Thanks for the reply,

Ive tried that, I even have a donor engine and have changed the cdi box, just the same. Ive also pulled apart every terminal and have cleaned them up, no difference.

 

[racerone]

Does spark jump a gap of 3/8" ( 1 cm ) , yes or no ?-----What happens if you put a few drops of fuel into sparkplug holes ?----Does motor bark when you pull it over ?

 

[Oil gypsy]

Thanks again, the spark was easily jumping 3/8, put fuel in the cylinders and it fired up, messed with the carb and for some reason the idle screw needed to be opened one and a half turns. I had it at the pre rebuild setting, for some reason its changed quite significantly, starts up fine now and runs smoothly.

I appreciate your help, I was so focused on ignition problems I wasn't following up the fuel side.