TOPIC: 1972 mercury 80 hp starting issues

I am having issues getting my 80- hp to start. We have done all the basics as far as compression( 100-105) on all 3 cyl. I was unable to test the 4th on the lowest part of the motor. Would that be the issue for this outboard not to start>?

I have done the following:

-replaced spark plugs
-checked spark on all plugs, good.
-checked compression on all plugs, good.
-replaced a very faulty internal wiring harness. (prior one was smoking out of the ground)
-removed and checked the starter, good contact on all points. cleaned the connections.
-no missing teeth on the distributor belt as suggested.
-I have opened the throttle when trying to start also, same issue
-battery is fully charged and the wiring harness was replaced in september.


thanks for any advice

100 seems low to me but I think it would still run with that. If the bottom plug is 0 then you could be in serious trouble. Seemed ready to fire off in you video. Two things come to mind. Does the choke work? If not you can cover the carb with your hand. Also a quick shot of carb cleaner into the carb will help it. It works like starting fluid but is not nearly as damaging to the engine. Hope this helps. And if your choke is broke and you need it fixed it can be super easy. Good luck!!

thank you Seymour, i will check that out tomorrow and let you know, thank you for the quick response.

It sounds like it is not getting enough fuel.
Have you rebuilt the carburetors?
I'm thinking your float needles are stuck in the closed position, and consequently not much fuel is getting into the engine.
If Seymour's suggestion works - go after the carburetors.
Doc

are you getting enough throttle advance with the fast idle lever.