I will start off by saying that I know this topic has been wore out, but I was unable to find direct answers to my questions in other forum postings.

Both in-tank fuel pumps are shot in my 1989 f150. High pressure in line pump is working. I would like to replace only the rear in-tank pump and convert to a single tank set up and completely remove the front tank.

To do this correctly, I believe I need to keep the dual function reservoir as a fuel supply to the high pressure pump when needed. I have gathered this information from other posts. Others mentioned that by simply bypassing the reservoir, issues may arise from the engine not getting enough fuel in high demand situations.

Now for my questions.

To mitigate the possible issue of fuel not returning to the correct tank, can I simply tie both returns together from the dual function reservoir with a T fitting and rubber fuel hose? Both returns from the reservoir would then be routed only to the rear tank if this became a problem in the future. I understand that the single function reservoir from a Bronco or single tank F-150 would be best, but those are nearly impossible to source.

Next, in the 1989 year the fuel selector switch in the cab only controls which pump turns on, correct? If this is the case, I should be fine to just leave the selector on the rear tank in which case would act as a single tank system.

If any of this is incorrect please let me know. With little knowledge about this system I am attempting to simplify it to get my pickup on the road.

 

I would get a 1989 Ford F-Series service manual and see how the single tank setup is done, and then emulate that.

 

That is strange that you lost both in tank pumps at the same time. I assume that you verified that there is power at the selected pump but it does not turn on? If you do not select the front tank then the valve inside the reservoir would not change position so how would fuel return to the wrong tank? My ‘89 F-150 sat for almost 10 years. When I got it back on the road the DFR was stuck on the front tank so I could not access the fuel in the rear tank. The switch should also change the selected sending unit for the fuel gauge.

 

I should have mentioned this, the truck sat for around 5 years before I got it. Was not getting fuel to the rail, pulled the rear tank and the in-tank pump was in pieces and rotted. Never did pull the front tank, but know that the front in-tank pump was not running and assumed the same issue.
My fear with fuel going through the wrong return is if the DFR is stuck as you mention. People in other forums had mentioned their other tank overfilling from the return line returning fuel to the wrong tank. I figured if I ran a single tank and tied the returns together this would never be an issue.

 

I replaced both tanks and pump assemblies with Spectra over 10 years ago. Only when I got the truck back on the road did I realize that the DFR wouldn’t switch to the rear tank. At this point you don’t know if the reservoir is stuck. What if it is stuck on the front tank any you replaced the rear tank. Now what? You won’t be able to get fuel from that tank so the returning fuel is irrelevant since there isn’t any.

 

If this was the case, couldn’t the lines be switched on the DFR itself? The pump would still be running in the correct tank, would just have to switch the rear tank lines to where the front tank lines would normally hook up on the DFR, right?

 

It would be much easier IMO, given all the issues, to convert the system to ITR.

 

ITR?

I replaced both tanks and pumps because of what was in the tank after sitting 9-10 years. I replaced the DFR with one from a junkyard after it left left me on the side of the road with a full tank of gas. I haven’t done anything to the fuel system since then and that was, I believe, over 12 years ago.

The OP does not know if there is anything wrong with the DFR or the rear tank pump.