i have a 91 ex cab 4x4 with the 3.0 and auto. when i start the truck i hear a moaning sound from the rear of the truck that lasts for 30 to 45 seconds then it goes away. it happens almost ever time i start it and it is loud. any ideas?

the truck runs fine and starts on the first couple of cranks every time.

 

Hmm.....I dont know what to tell ya.

 

uhhhh....peel the sniffer off of the tail pipe...lol

 

noisy fuel pump?

 

Ya, sounds like the fuel pump or something to do with your fuel pump. It could be a sign it's going to s**t the bed.

 

A moaning sound eh? :hillbill.

 

What about a small vibration along the muffler/exhaust pipe? Only takes about 30 seconds of run time to warm it up enough that it expands and the rattle/moan goes away. Does the moan occur every time you start the truck or only when it is cold?