Craftsman Model 917.276810

[bob106]

Need some info on the 19.5 hp briggs motor. The tractor was giving to me and is in pretty good condition. I don't know how old it is, so I would say maybe 5 yrs. old. The problem is the tractor turns over and I'm getting spark but no gas into the cylinders. This engine is turbo cooled which I haven't looked into yet. I can see gas pumping into the carb and tried starter fluid also. Could this be a timing or valve problem? I would appreciate any info in solving this problem......Thx bob106

[Mark / Ohio]

Welcome Bob!

Maybe the spark is coming at the wrong time in the cycle?
(Sheared flywheel key)


Does the engine seem to be pumping the usual amount of air? Can you feel suction on the carb and any exhaust air movement while cranking?
(Broken valve or piston connecting rod)

[bob106]

Mark, thanks for the reply. I'm gonna try and look at it a little more in depth this weekend. The correct model # is 917.270810. I'll get back to you and let you know what I found and hopefully it's not a major fix....bob106

[bob106]

Checked everything out and all was good but still can't get gas into cylinders or starter fluid. Good suction on carb and air moving thru exhaust and shear pin is good. Is there some other way to check timing? Any info would be greatly appreciated....bob106

[Mark / Ohio]

I just noticed that is a twin, one of the old style designs without the overhead valves.

http://www.searspartsdirect.com/part...&prst=&shdMod=

If your flywheel key is good the spark timing should be ok. Really no way for it to change aside from the magnets on the the flywheel being in the wrong position in relation to the crank position. Although that being said I suppose with an electronic ignition defect it might be possible for the timing to be off a hair. But I think generally they either work (plug fires) or they don't (no spark). If I recall correctly they fire both plugs at the same time on those.

So the plugs never get wet or you never smell raw fuel from the exhaust?


BTW, Briggs has a decent basic troubleshooting section on their website that you might find useful:

http://www.briggsandstratton.com/sup...olving%20tips/

[bob106]

No fuel out of the exhaust and there is good suction on the carb I believe. If it's not drawing fuel or starter fluid then I can't see it exhausting any gas. I'll try dumping some gas directly into the cylinders and I'm gonna check the compression today and I'll get back to you. Also will try looking into the electronic ignition...Thx bob106

[bob106]

Try spraying starter fluid into cylinders and nothing happened. I turned the motor over with my finger blocking the spark plug hole and had good compression on both cylinders. The carb has strong suction when I covered it with my hand which makes me believe the intake valves are working properly. I did notice on the one cylinder when I removed the spark plug it was wet but it still wont fire up. Gonna repeat the process with gas instead of starter fluid in the cylinders. I got good spark and everything seems to be in order for the motor to run. I would think even if it was a timing problem the motor would backfire or gas would come out the exhaust. Any info on this matter would be greatly appreciated. What am I missing????....bob106

[Mark / Ohio]

Originally Posted by bob106

... I would think even if it was a timing problem the motor would backfire or gas would come out the exhaust. Any info on this matter would be greatly appreciated. What am I missing????....bob106

Sounds like you have all the makings of at least a backfire or a small pop at a minimum from one cyinder.

[bob106]

Mark, was getting ready to take it to the shop and decided to pull the fly wheel even though the shear key was good. Well, the bottom of the flywheel was packed with dirt. Cleaned it out and to my surprise the mower started right up and runs good. I didn't think that any dirt would affect the magnets but live and learn. Thanks for the info and may the lawnmower gods be with you.....bob106

[bwdbrn1]

Who'd have thought. Glad to hear it's up and running.