wfd2

I have a '86 F150 4x4 5.0L w/ dual tanks.

My dual tank switching valve went bad a while back (like most). It had the filter inside (production before 2/86) so I simply removed the switch and put snapped in a 87-88 fuel filter in the pressure side lines of the front tank and rigged up a return line using the lines from an old fuel pump and rubber fuel hose. Runs great now because I think the switch was clogged up and not allowing full fuel flow.

However, when I get down to 1/2 tank, the truck acts as if it ran out of fuel and won't start. If I fill up the tank, it will run great until I the fuel gauge goes down to just above 1/2 tank, then it sputters and finally won't start until I put more fuel in (about 8 gallons to fill tank).

Anyone experience this before? Any ideas? I know my solution to the broken valve isn't "Ford approved" but I dont' see why this would impact the truck in this way.

Thanks in advance

dirtcrew51m

Possibly the gauge is off, or possibly there is a hole in the pickup tube in the tank sucking air when it gets to the hole.

Stinky

Don't know...but I had a '76 Celica....electric pump in the tank and it did the same thing. ONe day the pump died at a strip mall. As luck would have it, there was a Checker Auto Parts in the same mall. After we changed the pump, it never did it again.

Also, '95 Mercury Villager, it used to vapor lock. We changed the pump, never did it again.

If you suspect that your pump is the original one, then change it.

red1994ford

yep, like mentioned in ^^^ its most likely the fuel pump.

Mr.Distance

Having some of the same issue... My gauge was stuck past full, way way past. Thought it was my wires for a little while, but we went under the truck, wiggled those around, and the gauge started working. But, it only goes down to around 1/2 of a half tank.

I've thought of just running the tank 'till it was dry, or until my truck died, and then taking a gas bilge and seeing if there's actually anything in the tank. May help for you to figure out what's actually wrong if you try the same?

Just carry around a 5 gallon can (leave a little room), go do some pointless stuff, run around in a field if you're up for it, bilge once you're dry into the can to see if you've got anything left. If you're empty, just mark a spot on the dash where it's actually empty, and use that as your reference, unless you want a better fix. In which case, I say check your lines, or a new pump.

Just my two cents.