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1979 9.8 2 Stroke Throttle issue

M

Mikes2stroke

New member
I have this older Mercury. It starts and runs fairly well. But when I try to rev it up by pushing the throttle with my finger it stalls itself. I replaced the fuel pump gaskets, cleaned the carb as best I could. Some jets I could not unscrew. I replaced the fuel lines and am using fresh fuel. Why does it do this?
 
How did it run last season ?----Timing has to advance at the same time.----Or it will stall like you found out.-----What other trouble shooting was done ?
 
racerone said:
How did it run last season ?----Timing has to advance at the same time.----Or it will stall like you found out.-----What other trouble shooting was done ?
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A friend gave me this engine and it had been sitting a couple years, I believe. So perhaps if I operate the throttle with the twist handle thus advancing the timing she should run fine?
 
One thing on the carb, when I cleaned it the jet in the center of the carb I was unable to unscrew. Guess I worry that it is gunked up. But I will try running the engine again today and see if she revs up when I advance the timing.
 
It sounds like it's only running on 1 cylinder check the spark on each cylinder and the condition of the plugs; the motor will only rev so high in Neutral; will it go higher in Forward?; you have to set the low speed adjustment while the motor is running in F at about 1,400 rpm but first set the carb needle at 1-1/4 turns out.
 
If you have cleaned the carburetor 5 times then maybe it is not a carburetor issue.----Post compression test values.----And have you considered possible leaking crankshaft seals ?----Reed valve issues?-----You have inspected water pump impeller ?---That item needs replacement about every 3 years.
 
racerone said:
If you have cleaned the carburetor 5 times then maybe it is not a carburetor issue.----Post compression test values.----And have you considered possible leaking crankshaft seals ?----Reed valve issues?-----You have inspected water pump impeller ?---That item needs replacement about every 3 years.
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I have replaced the water pump, I haven’t tested compression as I don’t have a tester. If this matters at all it does feel like it has good compression, very stiff to pull. I cleaned the low idle read valve. One guy suggested To meet to try testing if the gasket between the carburetor and the engine might be leaking. I will look at that and also see if both cylinders are firing. Since someone on this forum had asked that question.
 
Finally this thing is running correctly. Thanks for all the advice! I cannot honestly say what fixed it. However, I have a strong feeling it was only running on one cylinder and that the float setting was off. Combined with all the other work I did, it seems to run great. It idles fine, it shifts into gear w/o stalling, and it revs up beautifully. I have a sense of satisfaction for sure and I learned an awful lot working on this thing. Never worked on one before!
 
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