Hello, I'm sort of new here. I've been a member for a while but I never really posted, I generally surf for information and what-not. I've been a member on NLOC since 98' though. (There was a 3 year hiatus while between trucks.)

...but, I have a buddy with a 92’ with dual tanks. He says that when the rear tank is switched on, it hard to start the truck without holding the pedal all the way to the floor until it catches and that it will wind up pumping the gas from the rear tank into the front tank! The more peculiar thing is when it’s switched to the front tank, it starts right up and there is no siphoning!

Any thoughts...?

 

You're describing 2 distinct problems, but the fuel transfer is a common one, and you can find MANY old threads about it on this BBS, & even more on FSB, using the SEARCH function. The short version is: replace the FRONT pump module (complete) to fix the fuel transfer problem. Put a fuel pressure gauge on the rail to find out why the REAR pump causes the engine to flood. It might have to be replaced, also.

Click my signature link & look in the EFI Fuel Pump album. Read the captions.

 

The next question would be what the ballpark cost to replace a fuel module. Where do you find them? He's unable to do it and I'm 3000 miles away so a shop would have to do it.

 

AFAIK, dealer only. I have no idea on the price, but I'd guess it's $150-350 just for the part. A decent shop should charge 1-2 hours labor to install it; a dealer will probably charge 3-4, but you can negotiate.

But he can do it himself using those photos & captions. I have another album called "Fuel Pump Access" that's a popular modification.