Dead spot when starting

H

hdtramp

Forum Newbie
I have a craftsman mower with a 17.5 hp briggs. It developed a dead spot when starting. I changed the starter and it has a new battery and I adjusted the valves. Didn't think it was a relay because for a while I could rock it to get it to turn over. That no longer works, and it just clicks like it's a relay or something. Any thoughts would be appreciated.
 
Since you hear clicking, your solenoid is probably working. But you can easily check to make sure it is and eliminate that possible problem. There are lots of videos on YouTube but my favorite is Taryl Fixes All. I suspect that your automatic compression release (ACR) is broken or you screwed up the valve adjustment. The lash needs to be correct or the cam doesn’t bump the exhaust valve releasing compression and your starter isn’t strong enough to turn the motor over. Taryl also has a video on that. You could take the plug out and see if the starter turns the motor over. If it does, then you have eliminated the starter, battery, and solenoid.
 
Take the spark plug out and see if it will spin over (cover the plug wire before attempting it), it it spins over your issue could be the decompression relief.
 
Have you adjusted the valves? The engine uses a decompression works on the camshaft. If the valves get too far out of adjustment it cannot activate the valve to release the compression.
While the valve cover is off and with the valves adjusted properly turn the engine over by hand and watch the bottom valve. It should go thru its normal cycle but there should also be a slight lift part way thru a turn this should happen as the piston is coming up on compression.
If you do not get the slight lift more than likely the mechanism on the camshaft is broken and the cam will need replaced. A common issue on these Briggs engines.
 
I had a very similar symptom. It was the safety switch connected to the clutch/brake. Intermittent failure.
 
When you adjusted the valves at 0.004 did you check to make sure compression release is working correctly. Check for 1 valve rocker movement just a tad, exhaust side, if no movement compression release on camshaft is bad. You will need to replace camshaft to repair it.
 
outdoorpowermike said:
When you adjusted the valves at 0.004 did you check to make sure compression release is working correctly. Check for 1 valve rocker movement just a tad, exhaust side, if no movement compression release on camshaft is bad. You will need to replace camshaft to repair it.
Click to expand...
Better check that again - the compression relief is on the bottom of the cam and the bottom lobe operates the intake valve. Don't believe me follow the ports.
 
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