1964 mercury thunderbolt 50hp

[dustinjohnson36]

I read and searched tons of threads the last couple of days trying to figure out my problem. I wasnt able to find exact issue so im starting a new thread.

Heres my issue- My outboard will fire right up on muffs, idle fine. But when I put it in the water and push the throttle the motor loses all power and stalls out. Heres some things I have checked, I pulled each of the bottom plug wires while running and the engine stalls out. When i pull the top two there is no change in the motor. Another thing I check was the bottom card has nice suction and the top carb has no suction. So im assuming it has something to do with the top carb. Whats your guys thoughts? Fuel is fresh, primer bulb is nice and tight, lines are clean. Ran sea foam through it couple days back hoping to clean the carbs out.

Thanks

 

[kazek]

Re: 1964 mercury thunderbolt 50hp

here is the start..compression test.just when u r doing that, check for a nice blue spark on each plug that should jump at least 3/8 of an inch(timing light would come handy also)

 

[Texasmark]

Re: 1964 mercury thunderbolt 50hp

Really, the only difference in idle and WOT, if all the ponies are with you at idle, is the spark is highly advanced (like moves from 5 BTDC to roughly 20) and you are supplying fuel to make the horsepower.

The service manual on the 90 3 cyl says that the low speed jet is adjusted such that the engine doesn't die on acceleration. It starts with the jets open 1 to 1 1/2 turns and then opened up slowly and checked for choking down. Opening continues (trial and error) till the engine will take throttle.

That's a condensed version of the process. Course on an engine of that vintage, you could have underlying problems such as low compression....do you know what that is for each cylinder?

Mark