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I am having trouble getting my Lt155 running, I have to to this point changed fuel filter and lines from filter to carb, removed carb and cleaned with carb cleaner, checked keyway to make sure it had not jumped time, replaced bad wire to coil. It cranks fine but will not start it just back fires. I have a strong spark on my tester. Any ideas? I am out of them!:confused2:

try a new spark plug, if your spark is good from the coil & you say the timing is good, check compression/valves.

I have a new plug in it but have not check compression or the valves, anyone know what kind of compression it should have?

bluetrac said:

I am having trouble getting my Lt155 running, I have to to this point changed fuel filter and lines from filter to carb, removed carb and cleaned with carb cleaner, checked keyway to make sure it had not jumped time, replaced bad wire to coil. It cranks fine but will not start it just back fires. I have a strong spark on my tester. Any ideas? I am out of them!:confused2:

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Just wondering how the engine performed before you changed filters, carb removed , cleaned and replaced? Backfiring can be from too lean a mixture, possibly from an air leak around the carb/block, or throttle shaft, etc. But that sounds like a long shot. How long do you crank it over until it backfires? Some backfires are like puffs~~and others are like shotgun blasts, which is yours? One of the other mechanics thought it might be a sticking valve and that would cause backfiring, but it looks to me like it would do that before you tore it down. I've had people bring me a mower to work on and I swear I'd be better off if I gave them $10 and sent them on down the road. Save a lot of headaches, troubleshooting woes, and dead ends in many cases. Keep us informed. Hopefully one of us will come up with a solution.

The reason I started working on it in the first place was: It would start and run, when I engaged the PTO it would die, so I began with the simple stuff first. When it backfires it it loud. To be honest and it now does not seem like a great idea, I tried the old trick of a little trany fluid in the gas to clean the carb. I drained the fuel and purged or cleaned the whole system in tess the fuel pump. It has not started since. I suppose it is possible that the jet is clogged and may need a kit in the carb??

Do a compression test.

In all the work on the Motor, Have you had the fly wheel off, i had 1 off 1 time, I would have put my Life on it , that the Key was in Place, jumped on it and nothing but Back Fire, I could not believe it could possible be that it was out of time, pull the fly back off and there Lay the key, Just Thinking, allso I have heard of a Key Just starting to shear, and cause this

LakeRat1

First I would like to thank everyone for the tips! Did a compression check and got 30lbs, It was a valve guide, reseated and braded it, she starts and runs now. Thanks again!