Fuel will not pick up and acts like it runs out of gas. This forum has been very helpful... But I just can not seem to find the problem. I have checked the wiring, replaced the fuel selector, the selector switch, and the fuel cut-off relay (under the hood)... I found that by unplugging and repluging in the fuel selector electircal connection a few times it started working... I was checking continuity at the connection. Whick was ok.... It actually worked very well for a few months. I vowed to keep the tanks over 1/2 way filled... yeah right... I let that idea lapse as I figured the problem was cured.

When the front tank got down to 1/4 on the gage. The problem suddenly re appeared. Won't start, no gas... or maybe when problem occurs the gage just go to 1/4 ? dunno.

I dumped a little gas in the carb, which was good for the 2 second test, wanted to go but of course wouldn't ...

Both tanks read the same, exactly 1/4... so went and got 5 gallons of gas at the gas station and added to front gas tank.... No help. still reads 1/4 on gage... both tanks.

I suspect some problem with the tank wiring, maybe a ground wire or something? But I have no idea what to check or where to look.. just seems odd that everything was working well as long as tanks were kept over 1/2 way full.

I might be able to get it working again by unpluging the fuel selector plug a few times... But that does not seem like a reliable fix.... I would appreciate any help or idea's .... also I drove on a very rough logging road this weekend, wonder if something shook loose causing an erratic problem ( the most fun type).

tia

 

I think some gas tanks had issues where the bottom part of the pickup tube would break off, so the pump could not get any fuel. I would try putting more gas into one of the tanks, and if that doesn't work, then I think you have a wiring problem.

 

Ok, I guess it is safe to assume you have the dual in-tank low pressure pumps same as mine. On the back of your engine is a two lead oil pressure switch, this powers the fuel pump circuit through a resistance wire once the truck is running. On your starter relay is a light blue wire on one of the small pins. This wire provides 12 volts through the relay to the pump circuit when cranking. Jump this to battery and see if either pump runs. If the pumps run this way, go jump the oil pressure switch wires. If it will run the pumps then, change the switch. If it still doesn't work, check your inertia switch (on the heater duct) and then suspect the tank selector valve as the actual pump change switch is part of it. I have the EVTM for the 86 models.

 

I have found another problem... the connector plug to the 6 port "hot fuel"fuel selector has a crack in it... I want to replace it but the Ford Dealership said the female connector is no longer available. I went to the local junk yard and none to be found.

Can someone help me. As to where I can get one. I have tried to call and e-mail our parts sponsors but they have never responded....

 

Bypass the lines around the valve and see if it will run on just the front tank. The dash switch selects the correct pump and sends a switching signal to the frame mounted valve. The selector valve on the frame selects the proper sending unit, and switches the fuel lines.

 

You can try NAPA if you have the Ford PN they can cross a lot of them to Echlin numbers. Unfortunately it won't help you now, but when I do the change to EFI on mine I will have that whole harness and valve and won't need it.

 

I thought I would continue this thread, as it might help someone else sometime... so fwiw.

I was able to find a used fuel valve selector Connector from the junk yard. Naturally that truck had the wheels off and sitting in the mud... But I got it.

I cut the old connector off and soldered the replacement connector on after shrink tube over the wires. But before wrapping it all up I wanted to see if it fixed the problem.
NOPE! same problem... no start, pumps not running.

So I got the trusty jumper wire out and jumped the little blue wire from the starter solinoid to the Battery... ok rear pump running and turned key on and checked front and rear tanks... both read the same. Rear tank reading.

So, I wondered if the front tank pump was shot? I ran a really long jumper wire to the selector valve wire front tank ( it was plugged in and remember left bare) on the selector valve connector to the battery... Vola' the front tank pump ran.

I thought fixed, not quite. When I hooked up everything normal. The front tank would not work... So, I put the selector switch on the dash to the front tank and used the trusty jumper solinoid to battery... The front tank tool off and worked just fine... I held my breath and flipped to the rear tank, it also worked just fine... everything back to normal.

I am still puzzled, is it possible for the pump and selector switch can get out of sync.?

Anyway I finished up the connector with shrink tube over the solder joints, wrapped it with black tape and packed the connector full of di-electirc grease... hope that is the right way.

Also 85lebaron2, when you mentioned changing the switch. Did you mean change the Starter Solinoid? I suppose low voltage or a problem it would not create enough current flow to the little blue wire..... I had already replaced the selector switch on the dash.

Also... the problem is always on the first start of the day after the truck sits out all night.... It cranks good so battery is strong.

Hope not to rambling. Thx again, I might be getting closer.
Never knowing for sure I keep that little jumper wire handy.