Me and my son just purchased a 91 RS. It has the 305 w/ a 5speed. The car drove ok. Once we got it home and really started looking I noticed a PO had installed a fuel pump under the hood (see pic). I didn't think those type pumps could pull fuel that far and maintain pressure at the TBI. I have not gotten under the car to see what is going on at the fuel tank yet. The car stumbles at higher RPMs. Any help is appreciated. Thanks,

Jim

 

Jim,

Generally I'd agree with you. They normally want those mounted as close to the tank as possible.

The only thing I can think of is the factory pump was still working, but low on pressure. Adding this as a "booster" was perhaps easier than pulling the tank.

 

Maybe i dont see it but all i see is an inline filter not a pump.

 

Knowing my luck he wired his new pump in and left the original unhooked and is trying to pull fuel through the in-tank pump. Looks like me and my son will be dropping the tank. Thanks,

 

That is the pump. Click on the thumbnaiil, then again on the photo, then again to zoom in.

Can you hear the in-tank original run when you turn the key on? Mine isn't super loud, but if it's quiet in the garage, I can hear it in the driver seat. Of course, you may have two running, so maybe have your son key it up while you listen at the back wheel?

 

Recommend removal of hood pump. Drop tank, replace pump w/tpi pump. Verify operation.

 

with external pumps, it's not -really- about how far from the tank it is, it's how much restriction you have on the inlet.

pumps like to push, not pull.

if it's sucking through stock plumbing, for example a dead stock pump and a filter (having the pump post-filter is extra stupid) you have problems.

if it was done properly, through a straight line with only a sock in the tank, and a filter after the pump, i wouldnt even worry about it, at least for now

 

I will see if I can hear the in-tank pump. I verified the stock filter is installed. But, will plan to drop the tank, install a tpi pump and remove the under hood pump. Thanks for the help.

 

A stock TBI in-tank pump is a turbine pump, rather easy to pull fuel through one.

I ran a TBI set up with an inline pump under the hood, no pump in the tank (retro-fit). It worked surprisingly well. Better then I expected. Before that I ran the TBI from the mechanical carb pump without a return line.

That too worked but vapor lock was an issue. Adding a return line helped with that, then went with the inline pump.

RBob.

 

Me and my son replaced the in tank pump with a TPI unit and got the tank back in. I have not started it yet, I wanted to remove the wire added by the PO to make sure he did not cut anything to have the under hood fuel pump run. But all in all a straight forward job. The fexible line between the pump and hard line was gone, which probably lead to the PO installing the underhood pump. We will get gas in it this afternoon and start it up. Thanks for the help!

 

Got some fresh gas in the car this evening and she fired right up. Idled fine, no surging or sputtering. Next on the list, change out the ignition lock cylinder and key. Then get a new steering wheel, but those are topics for other threads. Thanks again!

 

Outstanding! I hope you and your son enjoy this car.