Briggs 13.5 ic ohv

[RYANS']

Model. Type. Code.
21B807. 0290 E1. 0512227A.

My engine has a miss. I replaced carb, spark, adjusted valves. It runs but misses a beat every twenty or thirty seconds. Like it's starved for fuel for half a second. I've replaced the carb twice, cleaning and checking on the way. My only guess is there is a vacuum leak , or the valves aren't sealed. Any help appreciated.

 

[Mark H_NO]

You replaced the carb, what about fuel filter and lines? Have you checked fuel flow? Fuel lines break down on the inside, so you don't see it. If there's a fuel pump, what about the vacuum line?

 

[RYANS']

No fuel pump, fuel flow is good. Replaced the fuel filter. Thankyou. The mower is. Poulan Pro, 36inch ride on. 2006.

 

[Mark H_NO]

Where is the spark plug from? I hear there's a lot of clone plugs that aren't very good. Most recommend buying from local auto parts store. You replaced carb, is it running about the right RPM? The governor may need a bit of adjustment to get the throttle right. Are the carb mounting gaskets good? Air filter parts properly fitted? Have you checked the coil? How rusty is the flywheel? How old is the fuel in it? Have you drained the tank and started with fresh? Could be water in it.

 

[Auto Doc's]

Sounds like a bit of water in the fuel. Put a little 60% or 80% rubbing alcohol in the fuel tank and see if it clears up. Isopropyl (Petroleum based) alcohol breaks up small amounts of water. Ethanol (plant based) alcohol that is in modern fuel actually collects moisture from the air when left sitting. Not all alcohol is the same.

Edit:

Also blow back into the fuel line back towards the fuel tanks to be sure nothing in the tank nipple is straining the fuel through and limiting the fuel volume. Debris gets caught at the tank exit into the nipple but also binds up inside the fuel line creating a partial blockage.

A valve problem does not just come and go like described.

 

[RYANS']

Where is the spark plug from? I hear there's a lot of clone plugs that aren't very good. Most recommend buying from local auto parts store. You replaced carb, is it running about the right RPM? The governor may need a bit of adjustment to get the throttle right. Are the carb mounting gaskets good? Air filter parts properly fitted? Have you checked the coil? How rusty is the flywheel? How old is the fuel in it? Have you drained the tank and started with fresh? Could be water in it.

Champion spark plug, full throttle 3420rpm. Checked governor for play, none. Mounting gasket new. Swapped coil with another machine, same issue. Wire brushed fly wheel. Checked fuel, started a fresh lot, no difference.