Spark but no fire

TSWolf

Member
I am working on a 1979 Power King with a 16hp briggs on it. It ran fine until the coil went out. I replaced the coil, and found that the push rod wasn't pushing the points open properly, so I replaced that as well. Now, it seems to be getting strong spark, but it just won't run. Checked the carb, everything seems to be working and clean. Even with carb cleaner sprayed directly into the cylinder, it won't fire up. Does anyone have any idea of what could be the problem?
 
Check that you have compression,you may have a sticking,stuck or leaking valve due to carbon buildup on valve stem or carbon on valve/valve seat,if compression loss not the problem and eng has magneto ign check that flywheel key not bent/sheared changeing ign timing.
 
Had the head off and checked valves-no problem there. Also I am getting a strong blue spark from the current plug. No sheared key either. I did get it to fire once earlier in the day, but only once.
 
If eng has mag ign & coil mounted on an aluminum bracket held by 4 screws click on link below & read text about checking/setting armature timing same may be off,move mouse pointer over text & click left mouse button to enlarge.Another possible cause of problem head gasket leaking if you reused old gasket.
ign
 
1. Try another NEW plug. I was fooled just this week by a 'good' old plug that would misfire under compression.

2. Longer shot, but i have seen it happen: Are you sure that the valves and the spark are at the proper time?

3. Try a different jumper wire between the points and the coil. I had one that had a high resistance short once. Had spark when checked, would not run. This was on a battery ignition Kohler engine, though.
 
Get a new sparkplug then see if the engine will start. Do you have good compression? Hold your hand over the throat of the carburetor to see if there's good suction while a helper spins over the engine. Weak suction means low intake manifold vacuum. Hal
 
(reply to post at 08:22:24 12/07/14)
I take that this is a 32xxx series cast iron B&S? Try reducing the point gap to 0.018 this will retard the time some and may help, I've found some of the 32xxx series to be very sensitive to point gap others not so much.
GB in MN
 
I would check the plug too. You did say it fired ONCE> sounds like you may have sheared the key. Went through four keys on a twin "V" Briggs untill I found that the washer was bad. The convex is up and I had to add a lock washer before it would stay tight. Runs like a kitten now.
 
Pull the plug to see if it is wet. If it is, hold a long handle lighter next to the hole and turn it over to clear the cyl. Shoot some starter fluid in the hole install the plug and try to start it..
 
Ok, I determined the flywheel key was the problem. I got it running
with a new one, but it sheared also, and tried another with the same
result. What could be causing this?
 
When you installed the new armature did you line up the arrows in the mount plate and the flywheel? Its out of time most likely advanced a bit. Do you have the B&S Repairmans Handbook covering B&S engines 1919 thur 1981? If so go to page 46.
 
Recheck armature timing per instructions in link provided in previous reply,check that keyway in flywheel & on crank not worn/damaged,make sure flywheel tight to spec in text.
 

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