I have an 1985 F250 V8 7.5ltr XLT Lariott. About 2 weeks ago was driving on the front tank and it acted like it was not getting gas, switched to the rear tank. Ran fine for about another week. Only drive it 4 times a week about 20 miles each day. Then the rear tank started doing the same thing. Was switching between the 2 tanks and worked fine. Have an in line fuel filter and that was clean. Could not find a return fuel line which another thread suggested it might be clogged with plastic particals. 2 nights ago had to drive it 90 miles round trip. The 45 miles in had to switch the tanks twice. Filled up both tanks and for the first time the rear tank acted like it was full and kept shutting the gas pump off. Found the "sweet" spot and was able to fill it up. Have read other threads about this happening. Also added sea foam to both tanks. Drove home and about 35 miles into the trip home (freeway speed) again acted like it was not getting gas, tried to switch to front tank and lets just say that it did not go well. It did not die but sure bogged down and flipped it back to rear tank and proceeded to run fine. At lower speed I was able to switch between each tank with no problem.

Hate to take it in if it is something simple. Plus being a girl they just see extra dollar signs so I like to eliminate as much as I can before taking it in.

 

Most of the 460 trucks had a different fuel system. They had electric fuel pumps in the tanks, a switching valve with 6 lines going to it on the frame(under the driver's side cab/bed area) and a return orifice mounted near the carb with a return line.

There was added wiring and relays to power the fuel pumps, fed by a oil pressure switch on the engine.

Needless to say when things go wrong it can sometimes be difficult to find were the problem is.

I am going to guess, since it's happening with both the front and rear tanks, that it's something common to both tanks. And it seems when you switch the valve on the frame, it makes it start working for awhile. I am thinking it could be the switching valve that could be bad. It does have failure modes also, where the return fuel from one tank can go into the other tank and overfill the other tank. So I would lean toward it being the switching valve on the frame.

If you decide to swap out the switching valve, then that opens another can of worms. The Ford dealer will sell you one that will bolt right in and hook right up. But it's over $200 I believe. Autozone and some of the other stores will sell you the valve, made by the same company, operates the same, but the lines and the wiring plug are universal and need some rigging to get it hooked up. But it's way cheaper. I think it's in the neighbrohood of $70 but I haven't looked in awhile.

P.S. A lot of people have problems with this system, and some get rid of part or all of this system and go with something else. So look your system over to see if it's been changed around or not.

 

Did the Seafoam seem to help? I had a 79 F 350, with a saddle tank, that had some water in it. When I switched tanks once, it ran bad, barely running, even when I switched back to the main tank. Took a long while to get that one straightened out.

 

No the sea foam made no difference. Going to look into switching out the valve first. Anyone know if there are multiple parts Ford might of used or would this be universal? I had not realized but am finding out that Ford did not used the same parts for every truck. I will crawl under it and take a picture so I can order the part and hopefully get it running. Have not tested my theory but it seems worse when I travel over 45mph. Other than that and a small exhaust leak it has ran beautifully. Starts right up. And all the guys who work on trucks tell me the engine is in remarkable shape. I believe it only had one owner before me.

Thank you for all the help. It has been very helpful.

 

Parts stores (Autozone for sure) sells a universal selector valve. I'm in the same boat, 1986 F250 4x4 460. The selector valve is froze up, Ford wants $245 plus tax for it, and the fuel level sending unit is shot. You can replace the pumps but not the fuel pump assembly because no one makes replacement parts other than the pumps.

I thought I was going to use a universal (but specifically for an '86 F250 7.5l) selector valve from Autozone as I mentioned above. Drove 30 miles one way to the store that had it, opened the box at the counter and walked out. Bit more work than I want to do in my case because it may still not work.

It can be done and for $80+/- as well if you choose the universal. But I chose not to use one. I'm going fuel cell and replacing the whole fuel system, something serviceable and simple. Probably overkill but my fuel system has gave me nothing but problems ever since I bought the truck. Not to mention it's been hacked into in several places and it leaks.

 

Thanks for the post reply.

How difficult is it to convert it on over. Don't really want to sink a lot of money into this old girl but if it can be done for fairly cheap I have guys who can do it with me just buying parts and kicking them some cash.

 

It's not that it's difficult to convert over to the universal selector valve if that's what your asking. It's just time consuming. If someone doesn't mind a bit of wiring they might find it not to be all that bad. I couldn't get past the fact that I should be able to plug one in and go (like the OEM from Ford) and it work off the factory tank selector switch (the universal doesn't, it comes with a switch for you to install where you like inside the vehicle in order to switch which tank level reads on the gauge and pumps fuel from). In my case everything is so messed up I could have spent the $245 for the selector valve from Ford and it still probably not work.

With what you said your after the universal sounds like your best bet. It's unlikely that your fuel system is in as bad of shape as mine is so yours is more than likely worth going that route. Just remember that the fuel level sending units are not serviceable. Hopefully you get many problem free years out of yours.

 

Ok stupid question what is the fuel level sending unit and what exactly does it do.

 

The fuel level sending unit is a part of the fuel pump assembly which is inside the tank. It has an arm on it with a brass float. The brass float will naturally float on top of the fuel in the tank. As the fuel level changes the position of that arm changes because of the brass float on the end of the arm. The fuel level sending unit sends a signal to the gauge cluster and tells you how much fuel you have in the tank. (Or in our case how much we don't have).

 

Hell it sucks gas so fast the gauge goes down just as fast as the speedometer goes up. I get 8 miles to the gallon and the gauge has never seemed to be really accurate but if the front tank can over spill into the rear tank no wonder it has never been accurate.

Million dollar question is if that is bad will the truck still run. I have always gone off the mileage anyway so I don't rely on it any way.

Again thank you so much for all of your input and help.

 

Yeah everyone needs an operable fuel gauge, but us 460 guys really need one.

The truck will run with the fuel level sending unit inoperable. Mines inoperable as we speak. If your referring to the selector valve I don't know much about that other than mines froze up and will only utilize the rear tank. I would take a guess and say when they go bad they stick on one tank or the other but that's just a guess based on what I have read and witnessed. I have read about one tank filling the other tank up due to a faulty selector valve but I don't know anything about that other than it happens.

Your welcome, I'm no Einstein on the subject but I know were kinda in the same boat. Like I said my fuel system is coming out and going in the scrap pile. I've wasted enough time and money to have it still not work.

Just so you know which you may already, there are 4 port and 6 port selector valves. I would think you would have a 6 port but I really have no clue. Just be sure to check and see which you have before ordering the replacement. All you need to do is count the fuel line inlets and outlets.

I just remembered that there is some plumbing work to be done as well. You can read more on it here if you like: https://www.ford-trucks.com/forums/1...a-85-f250.html

 

Carol, this Rockauto link might help ........1985 FORD F-250 Fuel/Air Parts

 

You don't have to wire the universal switch for the universal valve. You just have to scratch your head a little bit on wiring the universal valve into the Ford wiring. I have a post from somewhere at home I can paste in where a guy figured it all out.

The simplest solution to get you running is to take the lines loose underneath and just run one tank, bypassing the valve all together. Make sure yo pinch the lines shut to minimize the gas running everywhere.

If you have the plastic lines, you can cut them off and slip them up inside regular rubber line with hose clamps. It seems to work well.

 

Carol, I have the same problem with my truck. I will post a link to the webpage:


Dual Tank Selector


I ordered my switch at ASE-supply.com I cost e $75 with shipping. It will be in Tuesday. They also carry the valve only at Napa for $119. plus S&H.
I got the whole kit with the switch, just n case my wires and connectors are getting very brittle. The valve is called a Pollak 6 port valve. They have a few of these at Amazon also.