1983 Johnson 140 hp

[Kendub]

Top two cylinders are receiving spark but no combustion and carburetors appear to be delivering fuel. Compression is good, too. Any ideas on what the problem might be?

Frustrated Kendub.

 

[gm280]

Re: 1983 Johnson 140 hp

If you have verified 100% you have spark and compression to support ignition and you know there is fuel, then the only thing missing is timing. But be very sure of all those things you THINK you have first. Don't assume anything without verification... Because you could be thinking you have those things and spend days scratching your head wondering what's wrong... YOu need four things for any engine to run, Fuel/Air, Compression, Spark, and Correct Timing... Leave any one of those things out and it will never run... So recheck each one again before marking it off your checklist...

 

[Kendub]

Re: 1983 Johnson 140 hp

If you have verified 100% you have spark and compression to support ignition and you know there is fuel, then the only thing missing is timing. But be very sure of all those things you THINK you have first. Don't assume anything without verification... Because you could be thinking you have those things and spend days scratching your head wondering what's wrong... YOu need four things for any engine to run, Fuel/Air, Compression, Spark, and Correct Timing... Leave any one of those things out and it will never run... So recheck each one again before marking it off your checklist...

How do you adjust timing on this motor? Checked all the above four times. At a loss.

 

[emdsapmgr]

Re: 1983 Johnson 140 hp

If the flywheel key shears, the engine will get out of time and won't start-period. If the engine is getting fuel, sometimes the engine will fire, even seem to backfire-due to the timing being off. You can check the timing on either #1 or #2 cyls with a timing light. Compare the flashes from the gun against the marks on the top of the flywheel and see if it firing as it rotates past the timing pointer.. I'd be very careful with adjusting the timing on this engine. It's somewhat of an ordeal to get it set properly. The aforementioned timing test should at least tell you if the timing is in the ballpark.