tarp818

Just purchased 1990 F150 4.9l with dual tanks and heres the problem.

Tank 1 works fine but fuel gauge always shows empty.
Tank 2- When I switch to it tank2 it stalls and dies but fuel gauge works.

Could it be a clogged filter or I'm looking at new fuel sending unit for tank 1 and a new fuel pump for tank 2? Any thoughts would be greatly appreciated.

Thanks
Tim

nauss85

I am in a similar situation. My fuel gauge reads over F for both. I need to get 2 new sending units. If I switch on the front tank, after a short time, it will stall out. It runs fine of rear tank. So either my front tank is empty, or pump is bad. I took it to the gas station, and I put $25 into the rear tank, then was going to put about 5 gal into the front. It wouldnt take any fuel at all. I stood there and kept trying to pump it, but every time I pulled the pump trigger, it would click off as if it was full...

So either I have a full front tank with a bad pump, or something is blocking it and I cant gert fuel into it and the pump is good... Rear tank is just the sender. Thinking of just replacing both pumps and both senders while I am in there. Have no idea of how old the working pump is...

I think you are correct in saying sender tank 1 and pump tank 2. (IMO)

techrep

iTrader: (1)

I think your correct...the filter... filters fuel from both tanks...so if it was that... tank 1 would not work either...very common problem

techrep

iTrader: (1)

Good call replacing both...pull your bed off...you will have access to everything...not hard at all.

nauss85

Thats my plan...just in case I think I will pick up some extra bed bolts in case I break them off...Is it 4 or 6 that hold it on? I use a 2010 and 2012 f-150 at work, and I think they have 6...

smt

well what happened? I just bought a '93 with the same problem, front tank wont feed. just wondering what you found and what you did to fix it

kbmoss

I had the same issue in my 88
To get the gage to read right you need new sending units. Got mine from rock for about 55 each.
As for one tank picking up and not the other it could be the pumps in the tank. Which some new sending units come with new ones. Mine did. My problem was the fuel tank valve. It sits on the inside of the left frame rail. They're known to go bad. Either the diafram or valves in it. The parts stores don't sell the oem style anymore. It's a universal electrical one you have to hard wire in. I haven't put one of these in yet so I can't help you there.

I took my original one apart and it was rough. O rings were missing and valves were stuck. I played with it and got the valves unstuck put it back together and it leaked badly. I was able to find some fuel safer tv silicone and I took it back apart and put it around the top and bottom where it leaked. You have to let it sit and cure since the top is pressurized from the front tank. That was a few days ago and the problem is fixed for now.