What would cause the engine to make a thumping sound (usually 1-3 times) after failing to start with the key off?

In other words, try to start truck, it cranks but does not start

Turn key back to off position and the engine makes a thud or thump sound almost like it is turning over slowly a few times after key is off.

Thanks!

 

Welcome to the forum.

Maybe ignition timing is too advanced. Just a guess.

 

Bad starter?

 

Is it something like a piston in a compression stroke not making it and getting pushed back? Sounds kinda like horse snorting?

 

That is exactly what is sounds like. Seems like compression pushing a cylinder. What would cause this?

 

Too much timing advance.

 

Alright, one more thing for the to do list. Thanks 73Shark and EinST.