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deere 318 onan b series

D

dbrojr

New User
lost left cylinder....seems to fire intermittently changed plugs,resealed intake,cleaned points and no arching, 90 psi compression in both cylinders...plug is dry after running and white.will run with left plug wire unhooked, but wont run with right side unhooked.does has over 30,000 hours on it.was used for over 10 years to mow 35 acres running non stop for 6 days a week/10 hour days.seems like it isn"t pulling gas into left side.exhaust does have an eye burning gas smell though.any ideas.ran fine last time plowed snow.
 
The last 2 onans that I worked on that would only run on 1 cylinder had valve seat problems.

One would actually fire the cylinder where the seat was almost in the intake port, but would not fire the cylinder where the seat was loose.
 
spark looks good....cranked over w/ intake and exhaust removed and valves are moving,havent pulled head yet to check valve seats...upper bolt in head gonna twist before it comes out ,i'm afraid.repower not in the budget...gonna sell it if comes to that...was my dads,so hate to get rid of it.
 
spark will jump a 3/4 inch gap w/ bright blue spark...switched plugs from side to side,no change...seems to be a fuel issue...if I flood it out for a sec both cylinders will fire for about a minute,then back to missing.

thanks for all the responses...
 
Sounds like you have an intake manifold air leak causing left hand cylinder to run very lean.

Spray some starting fluid around left hand intake manifold when running to see if it finds the leak inward. Be careful!
 
I had one that the plug wire was burned internally, I cut the wire and reinstalled the end and it was fine. One other thing to try is take the wire off of the plug but leave it close to the plug, if it runs you have found a bad plug, or wire.
 
removed intake and found a stripped bolt...fixed bolt and resealed intake..no leaks found..no change....checked carb as well.
 
drained gas and put in fresh.....seems to run fine now...will see when I get the deck on it.
 
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