Knocking noise

[Omegacsi]

I am having a problem with my 1991 Explorer, and I am starting to pull hair. I was warming it up, about a minute into this a loud knocking, almost a thunk, started in the back. I turned the car off, then turned the key back to the on position and the knocking started up again. I figured a fuel pump problem, so I replaced it. I then had to replace the fuel pressure regulator. Now the knocking has started up again. Any ideas on what this sound could be? The fuel pump is only 3 weeks old.

 

[arco777]

Well if it's knocking at idle, there aren't too many moving parts in the rear of the vehicle. Fuel pump is likely if changing it last time fixed the issue temporarily. But I've never heard of a fuel pump knocking.

I'm going to grasp at straws here but, thinking about all moving parts back there... does your rear wiper work as it should? Not got a busted internal linkage banging around in there?

Sounds like you need to get a mechanic's stethoscope and start poking around to find the source of the noise. Hopefully it is something simple.