fuel switch

[cewofford]

Ok check this out. I run off my front tank constanly. When i filled up my rear tank i switched over and ran off it and it ran fine, so i thought. After running on it an hour or so i noticed fuel leaking out of the fuel fill nozzle on the back tank. i switched back to the front and the fuel level was way down. Apparently the truck kept running off the front tank but also pumped fuel to the back tank and overfilled it. I know it doesnt run off the back cause i ran front tank low and then switched to back. Showing half a tank on the back and none in the front and with switch on rear tank i ran out of fuel. What are my possible problems?

 

[tjb]

This probably doesnt help you, but your front tank pumping fuel into rear tank how does that happen? Maybe the switch is bad and when flipped over doesnt close off to front tank but opens for rear and fuel is transfered while still running to engine? Is there a type of check valve in the line between tanks? On mine the rear sending unit doesnt work so I just use my front tank and maybe some day I will fix it.

 

[cewofford]

i have no idea why this happens i was hoping someone here would. or maybe there is a way to wire it different so it works my truck goes through 19 gallons pretty quick.

 

[LCAM-01XA]

your tank selector valve is shot, when they start pulling from one tank and returning into another that's a dead giveaway.

 

[cewofford]

thanks mlsc i thought that might be the problem. but wasnt sure. didnt wanna spend the money till i knew for sure

 

[snicklas]

your tank selector valve is shot, when they start pulling from one tank and returning into another that's a dead giveaway.

x2

I had an 83 F-150 351-M that had dual tanks. We had a FSV fail, I was driving the truck and had run the front tank out, and switched to the rear tank. I had been driving on the rear and was getting under a quarter tank, so I was headed to the gas station (Where my parents live, at the time it was 30 miles to the closest gas station), on the way to the station a ran out of gas, (the gauges had a bad ground and would "wonder" around so I was actually lower that I thought). Dad came out and brought a can, we put some in and filled the rear tank only.

Dad drove the truck a few days later, and just out of curiosity he flipped back over to the front tank, and it had a half tank in it. He asked me about it and I had run it out and it should be empty, we changed out the FSV and all was good......

 

[cewofford]

So can anyone go through the process of changing one of these on my 94. My haynes book is confusing as to which Fuel selector valve i have and where it is. Of course it doesnt cover diesels anyway. But if anyone has any suggestions or tips for doing this please let me know.

 

[snicklas]

It should be on the drivers side inside the frame rail. It will have 6 fuel lines total attached to it, 2 draw from the tanks, 2 return to the tanks (these are all on the back side) and a supply and return to the engine. It also has an electrical connector. It will be bolted to the frame rail. I believe is has the "quick dissconnect" type of connectors at the FSV, the type that take the release tool, like the ones used on the A/C lines. Disconnect the fuel lines and the power connector. Unbolt it from the frame rail, reinstall and the new FSV, reconnect the power and fuel lines and you should be good to go, It really isnt that hard, it is just somewhat time consuming and dirty.......

 

[cewofford]

seems simple enough. i think i know the tool you are talking about. used one on my in tank fuel pump change on 1998 chevy. Would i fing this close to the engine or close to the tanks or between the tanks?

 

[snicklas]

It should be close the the front tank, toward the front of the truck.

 

[sassyrel]

and when you do this--take a air blow gun--and blow on the back side of each of the fittings, to get the dirt out--if you dont--and use the proper tool--it will drive the dirt into the fitting--and youll have fun getting them apart---well,maybe not so much fun!!!-

 

[RLDSL]

Or you might want to consider ditching the electronic mess and putting manual valves in. I'm thoroughly ticked off after spending a fortune on a dealer fuel selector valve and a month later it got iced in the winter and it's never worked right since. in a few weeks I'm going to ditch the piece of junk and put a couple of manual valves mounted in the floorboard , one for the feed one for the return and be done with that noise for good.