Briggs intek backfires at full throttle and surge at low.

Iowa900

Iowa900

Forum Newbie
Hello everyone. Have a 23 hp b&s intek. Was mowing the other day. All the sudden I started to get a back fire through the exhaust. It has 164 hours. Changed the plugs fuel filter and air filter and no change. Compression was 128 and 125 a side. I’ve read camshaft horror stories. I’m hoping it’s not. Seems to surge at low idle now. Any ideas or places to start? I’d appreciate anything you guys can throw my way.
 
Also I can take off the left side park plug wire and it runs really rough like on the verge of dying but it stays running. If I take off the right nothing changes other than the back fire seems to disappear.
 
Close the choke 90% closed. Does it smooth out?

Clean the cylinder cooling fins. Neglect this yearly and you will eventually get some engine damage.

Spray flammable spray around carb and intake pipes slash flanges. If the engine smooths out you have a vacuum leak.
 
slomo said:
Close the choke 90% closed. Does it smooth out?

Clean the cylinder cooling fins. Neglect this yearly and you will eventually get some engine damage.

Spray flammable spray around carb and intake pipes slash flanges. If the engine smooths out you have a vacuum leak.
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Yes if I close the choke it smooths out. I’ll be sure to check the fins. I’ll also check for leaks!
 
Iowa900 said:
Yes if I close the choke it smooths out. I’ll be sure to check the fins. I’ll also check for leaks!
Click to expand...
Clean the fins first. This is not you main issue but needs to be done yearly. Clean as in CLEAN.

You have a fuel delivery issue.

1.Remove and flush out fuel tank.
2.Clean the carb internally with carb spray, compressed air and a jet cleaner of your choice. Make sure you have good fuel flow at carb.

Some carbs have welch plugs that cover internal carb passage ways.
 
The backfiring is unburned fuel igniting in the muffler
Remove the blower housing and remove the kill wires form the coils
Problem goes away = failed diodes

If the problem stays then swap the coils left right
Problem moves to other side = bad coil

Problem stays on same side = carb or valve problem
 
Anyone know of a good place to order a coil for this? Model number is 4455 77 1187 B . Not bringing anything up. Any help or a website to try. Thanks
 
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