Backfiring

[tithingman]

My 1997 jeep Grand Cherokee. 4.0 backfired and blew my muffler to a piece of sheet metal. Distributor is on number one. New wire distributor cap and rotor. Whats next?

 

[Jester32]

If the muffler blew up. It's usually from fuel pooling in the exhaust. Flooding. Excessive cranking. Leaking injectors. Etc.

 

[TerryMason]

There are guys here smarter than me, but I'll take a stab.

Did you replace the distributor, cap and rotor before or after the backfire? Improper timing or getting the plugs in the wrong order is a common cause of backfires. I'd start by verifying that you've got your plug wires going to the correct places.

 

[TerryMason]

Jesse beat me again...

 

[Jester32]

Like terry said though. If firing order is wrong it won't burn the fuel and can cause fuel to pool but usually backfires through the throttle body but I have blown up a muffler that way to lol.

 

[0III0forlife]

If it backfired with the magnitude to pop the muffler, i would say that the timing is 180* out, so, timing chain jump? but, a stuck injector can dump excessive amounts of fuel also causing the same problem as the other guys have said. would need more info to be able to help you troubleshoot it further.