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Recently I was gifted a non running MTD trimmer. When I give it a good tug the engine seems to have good compression. Seems to have good fuel delivery as the spark plug is always wet when removed. Replaced the coil pack with one from Amazon. Spark is nice and blue when gapped at the 20 mark on the spark tester. I used a business card to gap the coil pack. Any help is appreciated, thanks!

Check the timing key in the flywheel

Yes, I have checked the timing key on the fly wheel . That is still in tact and in good condition.

Try a fresh plug with a short shot of carb cleaner down the plug hole
Engine should fire once or twice if timing is good
If that works then repeat spraying a TINY amount through the carb
If the engine runs & can be kept running with repeated shor shots then you have a fuel problem
If not then you have a valve problem .

Sounds like a valve problem. I ordered an OEM tecumseh coil pack just to make sure. But I have performed all the above. Anyone have the procedure for performing a valve job?

But if valve clearance was the problem, I would not have compression. Am I correct?

is this a 2-cycle or 4-cycle engine? What model MTD is it. Kinda hard to offer advise without that.

Sorry it is a walk behind Murray with a 6hp tecumseh engine. Not sure what year but it does have a solid state coil pack

pour 1/4 teaspoon gasoline into the carb throat with the air cleaner off, and see if it starts. If yes and it dies then probably the carb is not working right. I just went thru this with a Tecumseh 5 hp engine. Was easier in the end to just replace the carb. It starts first pull and hasn't done that in years. Without an engine number or MTD number no way to tell what carb it has on it. You can rebuild the carbs but easier to just replace it if it runs with a 1/4 teaspoon of gasoline.

Santi8604 said:

But if valve clearance was the problem, I would not have compression. Am I correct?

Click to expand...

Well you started off saying it was not running
And valves can be open too far or not opened enough
A common problem is setting the valve lash on TDC exhaust stroke not compression stroke .
I check the ignition timing if the coil is suspect by putting the piston at TDC then painting a line on the flywheel where it passes the edge of the magneto
Thus use a timing light
The light should flash before the line gets to the magneto .

bertsmobile1 said:

Well you started off saying it was not running
And valves can be open too far or not opened enough
A common problem is setting the valve lash on TDC exhaust stroke not compression stroke .
I check the ignition timing if the coil is suspect by putting the piston at TDC then painting a line on the flywheel where it passes the edge of the magneto
Thus use a timing light
The light should flash before the line gets to the magneto .

Click to expand...

All good info I'm in the process of checking valve lash.