Popping sound after ignition off

[comandoed]

Have 1991 Explorer that I installed fuel pump after sitting for 6mo.

Now when am driving sometimes I hear popping(like backfire) under the hood
passenger side. ALSO sometimes when I park and turn the engine off I continue hearing the popping under the hood for about 60 seconds. Counted
60+ pops the other day.

What could it be and how do I fix this.

 

[FIND]

are they quiet pops, or loud pops like a backfire. A backfire is really loud actually.

If it is quite pops, the ones you are hearing after shutting the engine off is just stress from the heat soaking and some parts cooling down or warming up now that coolant and oil isn't being circulated. The ones while it is running is probably lifter tick, though it could be knock.

The ones after you shut the key off you cannot fix.


If they are loud pops, and your engine is still turning over after you shut it off, that is what is called dieseling, which would mean your timing is somehow way off. This would mean that the stuff you are hearing while it is running are a combination of backfires or knock.

 

[comandoed]

Both pops are soft to medium. I wouldnt say they are loud.

And when I turn ignition off the engine shuts off and yet continues to pop.

 

[FIND]

Both pops are soft to medium. I wouldnt say they are loud.

And when I turn ignition off the engine shuts off and yet continues to pop.

Yeah... that is just the expansion and contraction of the metals.... stress pops if you would....

 

[comandoed]

But I've owned 5 or 6 beaters Fords, Nissans and Mazda in the last few years
and never had this happen. The 91 Tempo and 93 F150 never dispayed this behavior
and both are Fords. Nor Nissan and Mazda.

 

[FIND]

some vehicles do it, some don't.

My old 98 contour would do it, one of my escorts did it, my old chevy c-10 did it, the explorer I gave to my ex-wife does it, my old grand prix did it.

My Lincoln never does it, most of my escorts didn't do it, my current explorer doesn't, my ex-wifes 99 contour didn't do it.

If you are really worried about the sound, record it so people can hear it.

 

[92exp4x4]

It could be anything without hearing the sound there is no way to start. Have you listened to it to try to find it? Pop and hood after shutting the engine down and see if you can pin point the origin of the sound.

I'm sure you are not describing the metallic ticking of the exhaust cooling after you shut it off. This has to be something different.

 

[1AJeremyD]

I would have to agree with FIND. If its a soft metal to metal pinging going on then its just stuff contracting from the cold.