Briggs 17.5HP Intek OHV single - rebuilt but wont run

11 years ago

A friend of mine has a Craftsman LT-1000 thats at least 5 years old. He threw the connecting rod in it and asked me for help. I replaced all the broken parts (connecting rod, timing gear, sump tube, new gaskets and seals)cleaned it out and put it all back together, now it cranks but wont run. My timing marks are perfect. (double checked it already at the cost of a new gasket) I didn't do a valve job as they seated well and compression felt strong. Adjusted my valve lash to .002 and put the engine back in. It cranks fast and smooth but wont run. I haven't touched the carb (other than checking to see if the bowl had fuel and if it appeared clean. both were good) or the governor arm as it ran before the connecting rod broke. I've checked for all the basics and there's new gas in the tank. It backfired at first and tried to start as if the timing was off. (Exhaust pipe got hot but no go) Hence, why I opened it to double check the timing marks. Now I cant even get it to backfire. The only difference between the first attempt to now is a new E3 spark plug (never heard of this brand before but its supposed to be more efficient) and the valve lash adjustment. Spark is strong and it flodded out on the second attempt. I just cant figure this one out. The engine model/type is 31H777 0297E1.

Appreciate any help or direction you can give.

Thanks, Bill

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Comments (6)

tomplum
11 years ago
Well, you may want to increase the valve lash first. 1/4" PTDC .003 int .005 exh. But then, pull the flywheel, replace the sheared key and resecure the flywheel to 100 ft #s. you want to know that the coil is not installed flipped either. they are marked on the lamination. Resetting the governor is simple should you need to.
wjs1820
Original Author
11 years ago
The shear key is good, I replaced it during the rebuild and the coil was never removed, I measured the gap at .010. I've tried not to mess with what was working (governor and carb). I'll reset the valve lash to your instructions Tomplum, Thank you. My thinking is to confirm the compression even though I think it's good and do a real leak down test. I'm going to pick up a compression tester and see what I've got. Otherwise, what else could it be?
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bill_kapaun
11 years ago
Since the compression release is in effect (with proper valve adjustment) your readings are compromised.
mownie
11 years ago
***The shear key is good, I replaced it during the rebuild"***
Unless you used the correct installation procedure and torqued the flywheel retainer to 100 Lb Ft, your above statement is only a presumption.
There is only 1 correct way to install that key.
Crankshaft and flywheel taper surfaces must be clean and dry....free of any oil, grease or dirt.
Lower the flywheel onto the crankshaft and THEN insert the clean dry key into the aligned keyways.
Torque the flywheel retainer to 100 Lb Ft.
Any deviation from the correct method might result in a sheared key upon the first activation of the starter.
A sheared key will still allow a spark to be generated.....it just will not be at the right time.
walt2002
11 years ago
Agree with mownie. I would remove the cooling shroud, flywheel screen, flywheel bolt & washer and look down the keyways with a pen light.

Walt Conner
wjs1820
Original Author
11 years ago
I never thought I'd be so happy to say I was wrong but at least I found the problem. You guys were exactly correct. The key was sheared in half. I have to order one but I'll put it in per above directions and let you know from there. Thanks for the advice.