I've inherited my grandpa's 89 F150 4.9L and I was told that only the front tank on the truck works. It runs fine with the switch toggled to either position, but noticed that the fuel gauge read beyond full when switched to the rear tank.

After getting under and looking at the fuel lines, it turns out the canister where the 2 tanks come in to is completely bypassed and they just directly connected the front tank with an inline filter up to what appears to be an inline pump.

My goal is to get both tanks working again. The fuel selector is not electrical. It looks like there are 6 ports on it (4 in the back, 2 in the front). Before I get into purchasing new lines to get this all hooked back up, is there any reason I should not try to hook these up? I assume it was switched to only be hooked up to the front tank because the fuel selector was not working properly. Ideally, I would like to have this working as intended. I don't think the electrical fuel selector is an option for me, or is it?

 

I did see a post about this and the dual tank system so do try to google it as I didnt save it.

Im in the same boat just purchases a 87 f150 4.9 and having some issues with fuel readings.

so I will try to help....ill I can look up the thread I saw about it later tonight as I need to go through my fuel tank system and sending units and fuel tank switch as well.

 

The fuel gauge and the fuel pumping system are two separate system and only share a common ground. They both pass through the fuel selector switch on the dash but are not electrically connected at that point.





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I've got to do something similar - my truck is also missing Tank #2 but the existing pump & line were wrapped up years ago. Hopefully they're OK but it's not a priority for me at the moment.

Sub'd to the thread so I can come back to it.

 

Thanks, this is exactly what I needed!

 

Just to confirm, I am trying to drain the main tank right now. I disconnected the line before the fuel filter. Then, I unplugged the pigtail from the fuel pump relay and jump the pins to activate the pump. When jumped, I hear something running, but it sounds like it is on top of the manifold and not under the truck there I see the pump. Additionally, no fuel is being pumped out of the line into the bucket I have placed under. Is there something else I should be jumping?

Edit:
Sounds like it is working, it's just that the fuel is trickling out of the line. I expected higher pressure, but the rear of the truck is jacked up and I believe the tank was pretty low, so perhaps it is all that the pump is able to grab.

 

When you ground pin #6 and turn on the key the selected intank pump and the HP pump should run:






The fuel pump an filter should look something like this:


The selector valve should look something like this:


The fuel shutoff Inertia Switch:

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Thanks for that. I'm guessing the reason the reservoir is bypass is either because it was faulty or the rear tank did not pump correctly.

I am looking on RockAuto for a replacement reservoir and all new fuel lines, but don't seem to be able to find them. It's only showing the electrical selector value, not the mechanical one. Do you happen to have part numbers for the reservoir and fuel lines, or a recommended place to purchase them?

 

You can order the reservoir from a Ford dealer but you must give the Ford dealer the part (Selector valve assy, p/n F1UZ-9B263-B).
OR
you can get one off of ebay.

 

Would there be any disadvantage to completely converting to an electrical setup instead of replacing these stock components? I just dropped the tanks to drain them and plan on replacing the rear. I figured since it is tore apart and needs all new hoses, it might be worth converting over.

 

Same boat with my 1988. Rear tank is present but fuel lines from it are gone.

Subscribing to see what you do and workarounds!

Good luck.

 

I found this write-up when explains the conversion: Dual Tank Selector Since I'll be eliminating the reservoir, my only concern might be with the tanks and how the pickup is located. If the fuel is low and I'm in a bend or something, it might have a chance to get some air into the lines, but I don't know if that needs to be a serious concern.

 

You will still need a reservoir for the HP pump when you go up hills and use WOT if you use the electric switching valve.

 

Hey Subford, if I was eliminating the reservoir to run off one tank. Could I use a fuel filter housing? Such as a glass bowl type used on tractors?

As for buying the dual fuel tank switch reservoir, fordpartsgiant.com has them listed for $188. But when I called they are back ordered for almost a year with no ETA when they will be in. They are apparently getting hard to find.

 

There is a used one on eBay now for about $80 shipped, but it's the only one I've found available. I'm also looking for aftermarket units.