Engine is dieselling

[ACF]

i run my briggs engine for an hour and when i shut engine off the engine will diesel (try to run backwards). engine starts up fine runs great. camshaft was replaced 3 months ago. what could be cause and the fix

thanks

 

[Hammermechanicman]

What is the engine model number? Can you post a pic of the spark plug and what is the numbers of the plug?
When you sad dieseling is it running on when you turn the key off or just kicking backwards once when you turn the key off?

 

[ACF]

model 331877-1371-b1 will send pix of plug later,
trying to run when key turned off

 

[StarTech]

Hmmm, I never seen a Briggs to come to a hard stop and start turning backwards during shut down.

Now I seen them to run longer than they should when the ignition coil kill circuit fails and the shutdown starts to depending on the fuel solenoid to shut down the engine.

 

[dana a]

I believe over heating can cause it to run after the key is turned off.. Clean the dirt and crud off the air fins and see if that fixes it.

 

[sgkent]

"what could be the cause of this?"

anything that either allows the coil to continue to work such as a corroded kill wire ground, corroded kill switch, or ANY hot spot in the combustion chamber including sharp surfaces, carbon, or other such as a head that is too hot. Heat, excessive compression, and a lean mixture can contribute to it. Try premium gas if you can't figure out the cause.

 

[ACF]

changed out the ignition switch did not solve the problem. could a clogged crankcase breather cause the engine to build up pressure since it is not allowing excessive to vent off, thus when you turn the engine off the pressure is vented off via the pistons and causing combustion in the cylinders of the engine until pressure is released. just thinking outside the box what does the group think any comment would be grateful thanks

 

[Hammermechanicman]

Dieseling and running on (fuel solenoid off but ignition still on) look totally different. Dieseling from a carbon hot spot or over heated spark plug electrode results in engine operating erratically and usually making some off knocking sounds. With run on the engine just slows down and dies. Which do you have?

 

[ACF]

Dieseling and running on (fuel solenoid off but ignition still on) look totally different. Dieseling from a carbon hot spot or over heated spark plug electrode results in engine operating erratically and usually making some off knocking sounds. With run on the engine just slows down and dies. Which do you have?

mine makes a knocking sound

 

[Hammermechanicman]

Dieseling is usually caused by either carbon buildup that is very hot from a hot running engine or more likely overheated sparkplug tip from either the wrong heat range plug or very hot running engine. What does the plug look like?