lgt2654 running on one cylinder ideas please

[spanky324]

26 hp briggs only running on one cylinder (I pull one plug wire and nothing changes) new plugs any ideas??

 

[ILENGINE]

Check for spark on the cylinder that is not firing. If you have fire then check the pushrods to make sure they are still in place and straight.

 

[spanky324]

Check for spark on the cylinder that is not firing. If you have fire then check the pushrods to make sure they are still in place and straight.

its has spark and the pushrods/rockers seem to be normal when cranking with cover off !what next??Thanx

 

[reynoldston]

its has spark and the pushrods/rockers seem to be normal when cranking with cover off !what next??Thanx

How did you check the spark and what is the compression on the cylinder not firing? There could be several reasons for this, compression, spark, fuel, timing, you will find one of these things missing with the last two not that likely but not impossible. I might add plugged exhaust.

 

[spanky324]

don't have a compression tester but I checked for spark by cranking it with a plug touching ground --great spark-I could hear compression though--valve adjust maybe??

 

[spanky324]

ILL borrow compression tester tomorrow any special procedure that needs to be done?Like both plugs out or squirt oil in cylinder ?Its been awhile!

 

[reynoldston]

don't have a compression tester but I checked for spark by cranking it with a plug touching ground --great spark-I could hear compression though--valve adjust maybe??

The proper way of checking spark is under compression with the plug in the engine with a tester and also make sure the spark will jump a good 1/4 inch. As for myself I find its impossible for me anyways to check compression without a compression tester or a leak down test. Just don't have a feel for it. I am doing this work on customers equipment in my shop also and have all the tools to do this. Not that hard to check for a tight valve with a feeler gauge so that may be your next step ?? Buy a new spark plug they are very inexpensive.

 

[spanky324]

ill check out the valves --I got two new ngk plugs too!

 

[bertsmobile1]

ILL borrow compression tester tomorrow any special procedure that needs to be done?Like both plugs out or squirt oil in cylinder ?Its been awhile!

Both plugs out, throttle WFO ( not choked ) dryI like to
I like to do it by jumping the trigger on the starter solenoid, so the ignition is off thus no spark.
You can do it again after squirting a little oil into the cylinder and revolving the motor a few time to distribute it. called a wet compression test.
Only old farts like me do this. A difference of 10% or more = bad rings.
You need something better than 75 psi for the engine to fire even allowing or decompression.

You might like to try shoving the piston down with a stick while you rotate the engine to check the rod & crank are still together

 

[gainestruk]

Both plugs out, throttle WFO ( not choked ) dryI like to
I like to do it by jumping the trigger on the starter solenoid, so the ignition is off thus no spark.
You can do it again after squirting a little oil into the cylinder and revolving the motor a few time to distribute it. called a wet compression test.
Only old farts like me do this. A difference of 10% or more = bad rings.
You need something better than 75 psi for the engine to fire even allowing or decompression.

You might like to try shoving the piston down with a stick while you rotate the engine to check the rod & crank are still together

My thoughts also, you could have broken rod and valves would still work.
With spark plugs out you can put your thumb over hole with good compression it will push your thumb off (you still need to do compression check) if you don't get this on dead cylinder you need to put screw driver in hole go till it touches piston bump starter or roll over by hand to move engine if piston doesn't move you will need to open engine up to see what happened.