my 84 with a 300 6 and dual tanks died on me this mornig on the way to work in a hurry i figured out it wasnt getting any gas i used the replace and pray method and put on a ne fuel pump and filter and still nothing. on the way home from work the day before it kept spudering when i would hit bumps like it died for a sec. but when i got home my battery cables were lose so i figured that was it problem solved well i was wrong. well i just crawled underneath it with a flah light and really started looking i notice a line with a very small leak comming from the rear tank but i wouldnt start on either tank so i dont thnk thats the preblem then i notice a well i guess i dont know whats it called its the part were both fuel lines from both tanks hook together and go into what looks like a switch or sending unit. the strap that holds that to the frame id busted and the little tube thing is just hangging there if that has to be groundeed to the frame thats my problem if not i need help but i really hope that starp is the prob becasue its not touch the frame to get a ground. thanks and soory about the crappy typing im in a big hurry. thanks agin

 

wish I could help you...my truck wont start at all and i was suppose to be at a new job today and yesterday. =(

 

i found out its called the tank selector switch i think. if it has to be connected to the frame for a groud that would be whats going on i think. because if theres no ground the switch wont work and then both tanks are close and no gas can flow. i just need someone to comferm this for me because the new one is 40.00 and i allready put 30.00 in to a new fuel pump and filter and misc hose stuff. but its just my work truck and i dont want to put a bunch of monery in to it especially on the wrong parts, thanks

 

I had a problem with my 86 F250 where it would start up and run for 5 or 10 seconds then die. I found out that it was two relays that I found under the hood by the driver side firewall. They cost me about $10 each and solved my problem. (After 2 new in tank pumps, and a carb rebuild) You might try those. I don't know if there is a way to test a relay before buying, but they're cheap enough anyway. Good Luck! As far as the tank selector switch, I don't THINK that both tanks can be shut off. It's either one or the other.

 

yes theres a way to test the relays...need a voltometer thingy...

 

You do need a voltmeter however you have to check to make sure that it is the switching valve and not the actual switch in the truck. What I would do and did do with my truck was I just disconnected the switching valve and ran it strait from one tank to the carb. Its alot easier to do unless you desperately need both tanks though I cant think of any reason why you would.

 

hell im 18 but u can take my advise if u want but i think u should use a voltmeter to check everywhere the fuse ports and on the relay its self and i but i think it has to be grounded but i hope u get it fixed...

 

i fixed it after work today i was going to try and gound it out or replace then i found some fuel line so i just hooked up the front tank and it runs great. thanks i dont know if i will replace it or not

 

what years fit my truck for the fuel tank valve i have a 1991 f 150 i would like to try and use if it will fit if not i know were there is one in a junk yard or wouldnt it be worth my time meassing with a used one. im kinda bkoke

 

It wont fit. You have to get the ones for an 80-85 because they are for trucks that have mechnaical fuel pumps.

 

There may be a problem with the rear tank. If your valve failed it should have defaulted to the rear tank.