[dillon.melfa06]

I am currently building a race mower using the Frame of a Wheel Horse. I had to take the old engine off because it had been sitting for about a decade and was filled with moss and mouse nests. I replaced it with a Craftsman Intek 18.5 and that was working beautifully. But one day, about a month ago, I had the mower idling and when I went to give it more gas it stalled out and wouldn't start back up. It has spark, air, fuel, and its running 90 psi for compression. That is low, but it ran with that before. I have been trying to start it and the best I got was it running for about 5 seconds and I could only do that once. Any ideas on what the problem would be?

 

[ericforster]

How did you test spark? Using a spark tester wont but that doesnt tell you if you have spark in the chamber. Spark plugs go out. How did you test for fuel? Wet plug ? What if you spray carb cleaner into the air intake? Is a valve sticking open? Does it have a fuel pump? Is the fuel pump operating properly?

 

[dillon.melfa06]

Eric, first off thanks for helping and as for your questions, I used a spark tester, but I also verified the spark by setting the spark plug (brand new) on the block and watching it spark. I don't know how to verify if there is spark in the chamber, but when I spray starting fluid in the cylinder nothing happens. I have gas in the bowl of the carburetor so I know it is getting fuel + the spark plug is wet when I take it out. I have verified that the valves aren't stuck and are adjusted properly. And there is no fuel pump on this engine.

 

[ericforster]

You may have a clogged jet on the carb. This happens beause some small peice of debris gets in there or bad fuel. Do you have a fuel shut off selenoid? These also commonly malfunction. To check the shut off selenoid, simply put a finger on it when you turn the ignition from on to off. You should feel and hear it click open. If not, thats a problem.

 

[dillon.melfa06]

There is no shut off solenoid on the carburetor so I know that's not the issue. Back to the spark issue, I can see that I have spark (and the spark tester can verify that), but when I spray Starting Fluid in the cylinder it doesn't pop. Even with weak spark it should still pop right?

 

[KennyP]

Might want to check the valve lash. B&S engines need that reset every so often.

 

[FrankIII]

Might want to check the valve lash. B&S engines need that reset every so often.

Yes.

 

[FrankIII]

I have an little 5HP Briggs that wouldn't do anything, no matter what I tried. Turned out that the crankshaft keyway was damaged, and that caused the flywheel key to shear. Then the timing got so badly off I couldn't get it to make a sound. Might want to check your flywheel key, although I can't see how yours would have sheared.

 

[FrankIII]

By the way, you can't really check the compression on these mower engines accurately because they have a compression release.

 

[ericforster]

I have an little 5HP Briggs that wouldn't do anything, no matter what I tried. Turned out that the crankshaft keyway was damaged, and that caused the flywheel key to shear. Then the timing got so badly off I couldn't get it to make a sound. Might want to check your flywheel key, although I can't see how yours would have sheared.

I have seen flywheel keys shear from a a slight backfire when the engine was shut off. Although not common in my experience, it does happen.

 

[Vigo]

I was going to say check for a crank key issue too so glad its already covered! As for a way to check for spark in the cylinder, one indirect way to do it is use an inductive timing light. Dont really have to point it at any particular thing, just if it flashes, you probably have spark in the cylinder. Not 100% guarantee but close.

As far as checking for a sheared crank key without taking off the flywheel, you just want to take the plug out and get the piston close to top dead center, and then look at the flywheel and see if the magnet is close to the coil. This is very inexact but ‘magnet should be near coil when piston is near top of cylinder’. That’s enough to let you quickly identify if the flywheel is in a totally wrong position compared to the piston.

 

[dillon.melfa06]

Thank you everyone for your help. I will check the valve lashes, but as for the crankshaft key I made sure to check that because I heard that was a common issue. I will check the valves then get back to you.

 

[dillon.melfa06]

I have adjusted the valves correctly. As for the timing, I have taken off my flywheel once and the key was fine. This was recently so I know it's still fine because it hasn't run since then. The timing should be fine then, right? I am also putting a new magneto on the engine (On Monday hopefully). I'm hoping it is the magneto because that would be a really easy fix. Again thank you to all who have helped me on this project.