I've got an 86 F-250 4X4 460,4spd. its got dual tanks on it and the fuel pumps on it went out.So what I did was drop the tanks pull the factory ones out connected a piece of solid copper pipe to the sending unit for fuel pick up.Installed a 12 volt aftermarket electric fuel pump and put it all back together.I also had a auto repair shop in town install a new fuel tank selector switch.
Now what happens is driving the truck and it will just shut off. U open the hood and look in the fuel filter and theirs no gas.The pump is working but no gas flowing.Wait about 10-15 mins. and it will start pumping gas,the truck will start up and go again.

The tanks have plenty of gas in them so I'm wondering if maybe the tank is vapor locking or the gas caps aren't venting properly and causing a vacuum and the pump can't pick up gas is just sucking air.

Or I'm wondering if the fuel pump is getting wore out and its getting hot.It's been about a year since I've done all this but before what it would do was run out of gas on the rear tank u switch it over to the front one it will pickup gas and go.
Now it just shut off's u wait a little while it will pick up gas and go again.

It's got me riddled I've had to walk home 3 times to get help.

Dan

 

Try pulling the gas cap off when it does it. Protect yourself from splash! If it's not vented right you will probably hear a woosh. Also fuel filters/tank sock could be a problem.

 

Most electric pumps do not suck very well and must be mounted below the tank level.

 

Yea on mine I have the fuel pump mounted on the inside of the frame rail right under the driver's side door and it is lower than the gas tanks.
Thinking back now I have noticed that sometimes when I go to fill the tanks up w/ gas when u take the caps off it will make a wooshing sound and u can hear the tanks banging around like their expanding from pressure inside.

I did drive the truck today about 30 miles w/ the gas caps off and had no problems w/ it so I'm thinking of trying to find some vented caps to go on their instead my old locking gas caps.

Thanks,
Dan

 

Sounds about right. You may also be able to remove the purge solenoid in between the tanks and charcoal canister.

 

I have removed all the emission control stuff off the truck.The smog pump is gone,I plugged the holes in the heads for the smog manifold system w/ steel plugs.It didn't have cat.converters on it cause its over 8,500GVWR.The fuel tank vent lines that went to the charcoal canister I just tied up in the frame.
I'm gonna go to the parts store and get some vented gas caps and put on their and see what it does.

Thanks,
Dan

 

Good luck