Only one cylinder firing

[chas1]

Could anyone tell me what could cause only one cylinder to fire on a 1992 40 hp, electric start, with tiller handle. Are the coil and the powerpack the only 2 items that would cause it to fire on one cylinder only? I checked the coil by reversing the leads from the powerpack to the coil and got fire to the plug that wasn't firing before. It looks like the coil is good so it has to be something from the powerpack back. Any idea if it could be something other than the powerpack?
Thanks for any and all help
What a great forum we have here.
Chris

 

[tslarson]

Re: Only one cylinder firing

The only components that will cause no spark on 1 cylinder are the coil and power pack. Since you have eliminated the coil, must be the power pack.

 

[chas1]

Re: Only one cylinder firing

Thanks very much for the information, just needed to be sure before spending $100 on a powerpack.
Thanks again.
Chris

 

[chas1]

Re: Only one cylinder firing

I have replaced the coil, and powerpack, swapped plugs,and wires still have no fire to the same cylinder. Are there any component under the flywheel that could cause one cylinder to not fire?
Thanks
Chris

 

[Joe Reeves]

Re: Only one cylinder firing

There is only one sensor in the timer base under the flywheel. If it causes spark to even one cylinder, the sensor is okay.

Are you assuming that there is no spark to that cylinder (you don't say which cylinder) simply because that cylinder is not firing, or have you actually (with the spark plugs removed) performed a spark test?

Using some kind of spark tester (do not use the spark plugs for a spark test), set the gap to 7/16". The spark should jump that 7/16" gap with a strong blue lightning like flame, a real SNAP!

What type spark do you have, and if faulty, describe it. Also describe exactly what you find on all cylinders.

What is the compression reading of each cylinder?

 

[chas1]

Re: Only one cylinder firing

Here's what I've done so far:
Did the wide arc test to both wires from the coil- no spark on top cylinder.
Swapped leads from the powerpack to the coil and got spark on the top cylinder coil lead but not the bottom lead. This tells me the coil should be ok(it has been replaced anyway).
Replaced Powerpack and still no fire from the same lead coming out of the powerpack to the coil.
The spark is a great spark but only from the one spark wire that is hooked up to the coil from the good lead from the powerpack. By the way the motor specs are:
1992 electric start
Model # E40TELENJ
Thanks for your input and continued help
Chris

 

[chas1]

Re: Only one cylinder firing

FYI
Found the problem, pulled the flywheel and found one of the three wires from the timer base had worked loose from the part to close to solder or fix. Looks like a $175 problem.
Thanks for the feedback and help.
Chris