149 Won't start now! Stuck Valve?

[105_Tom]

No problems until now. I went to start my 149 two days ago, I choked it as usual, and just as it was catching, it sneezed out the carb and quit firing. I have spark, a good spark plug, plenty of fuel, but I'm not sure about compression. I know I have the compression release set up, but compression is not that strong with the old thumb over the plug bore test. I'm out of ideas. It just blows fuel back out of the carb, and soaks the plug. It won't even fire with ether or gas directly poured into the cylinder. Any ideas? Is it time to pull the head and see what's going on? No funny noises while cranking. These engines are not supposed to flood because of the ACR, right? I'm afraid if I just keep cranking, I'm going to wash out the crankcase with raw fuel.

[cwmcbee]

I usually just lurk here Tom but, it sure sounds like a stuck valve to me. I'm sure the regulars will jump in here soon.

[Rhoderman]

Sounds like a stuck valve or you inhaled a chunk of debris or carbon into the intake. Take the carb off and look at the valve stem. If there's a shiny spot always visible on the stem, the valve isn't moving up and down as far as it used to. Also, check your carb throttle plate and choke plate screws to see if they're still there.

The ACR affects only the Exhaust valve. If, after you get the carb off, and find the intake is hanging open, you might try rotating it with a needle nose pliers on the valve stem. Be sure not to mar the shiny part, stay on the crusty part. If it moves down, put a bit of PBlaster on it and see if it will run. A valve job is probably in your future.

Also, you may have had a valve seat come unseated. If that's the case, you should fix it now since it will wallow out the block if it's loose.

[Yosemite Sam]

The guys are probably right about the valve, watch to see if it moves when you turn the engine over. In any event you're most likely going to have to pop the head off, if you haven't been in there in awhile it's probably time to decarbon anyway.

Good luck.

[eastonct124]

Everyone's correct. Backfire out the carb, means one thing....valve isn't closing.

[Cvans]

The Backfire can also mean a lean fuel setting. Many engines will backfire through the carb. when running out of fuel.
Chris

[dieseldog558]

i had one to do the same thing,while cranking i noticed i felt compression around the head so i pulled the head and there was a crack in the head

[dieseldog558]

i also see that alot of times the inner air cleaner hsg screws come loose and fall out and get sucked in through the carb and hold the intake valve open

[weaverama]

I had the same issue. A bolt holding the air cleaner shroud in place came loose and got sucked into the intake and hung a valce open.

[aagitch]

My backfire problem was caused by incorrect carb settings.