Fuel tank switch bypass

[Mulochico]

Well, I finally did it and it works great! A little history. A few months back I posted to get ideas. My tank switch went bad (pulled off of the front tank, returned to the rear tank) (?). I thought about replacing the factory switch, to much money for something prone to failure. Thought about manual switches (2 needed, 1 for supply, 1 for return), at $70-80 each I wanted to look into other options. I decided on the Truckers fix (I am one of course), gravity feed between the 2 tanks. Pull out of the front (a little lower tank) return to the rear. I took some time to figure out parts, etc. and I came up with the following. About $60 total with a few days work (most was waiting for sealer, JB weld, to setup (15hrs)).

So here it is.

Parts: Purchased Plumbing @ Home Depot, Fuel line @ AZ
2 Valves ½” id. (Need to be rated for oil as the ones only rated for water might not last w/fuel)
4 Steel washers ¾” `
2 Elbows
2 5/8" Hose Barbs
5’ Fuel line 19/32”
13’ Fuel line 7/16” (to run new line)
13’ Fuel line 3/8” (to run new line)
10 Hose clamps (2 0n larger hoses between tanks, 8 for fuel lines)
1 3/8” bolt (to block off line) 1
1 7/16” blot (to block off line) 1

You will need to remove both tanks at different times throughout the process so you will need to plan which tanks to drain (they are a lot easier to handle empty ) if you are going to need to use the truck. I did the front tank 1st as this let me plan where to put the fittings and I also had air getting into the lines when I was pulling off of the front tank thru the switch (this was resolved when the switch was no longer used).

See pics for the layout of the parts as they would be installed. (note: I had to cut off the larger end of the fitting that is in the tank otherwise it would limit the amount of fuel available in the tank) The washers are installed 1 one the inside, 1 on the outside of the tank.

I had to drill a 13/16” hole in the tanks (front tank = low and on the side, Rear tank = bottom front drivers side) and enlarge the washers to accommodate the fittings. Also, I had to cut a notch out of the skid plate under the rear tank for access. You need to be sure you can reach into the hole for the fuel p/u to be able to tighten the fittings. If you do not plan this ahead you just might end up with only a holy fuel tank!!!

These are pics of the finished product:

I used JB Weld (regular not Quick to give more time to get things in place before hardening) as a sealer. I wanted more strength at the tank to avoid the possibility of something hooking the valve and ripping it off of the tank. I also sprayed Brake-Kleen to remove oil residue before sealing it up for a good seal. I have the valves setup so that there is as little chance for something to hook on them as possible and still be able to use them as needed.

The connector hose between the tanks has to be at pointed least a little downward or level with the front valve to make sure that the fuel will feed into the front tank. You also have to watch that it is a little loose as the rear end could force some parts up so leave a little slack (I zip tied it to one of the e-brake cables to avoid contact with the rear end)

I have not rewired the sending unit for the gauge yet. I just moved the switch out of the way and left it plugged in so that the switch on the dash will allow me to use either sending unit. I also have, as stated earlier, set it up to pull off the front and return to the rear tank. This has allowed for a good fuel flow and venting of the system.

Some people who have done a similar mod chose not to use valves at each tank. I chose to use valves as this allows me to disconnect either tank if needed, drain a tank if needed, etc. It just gave me more options. I also ran new fuel line from both tanks (supply and return) to where the switch went, plumbed the lines I needed, capped the ones I didn’t, this will allow me the option to use only 1 tank if the need arose.

I hope this gives someone else an additional source for ideas to make their truck better.

 

[Mat J]

mine is set up similar but no valves which is a great idea.

my fittings are brazed in and adapted to jic flare fitting and used #8 hydrolic line for the vent and feed line between the two tanks. i also pull and return on the front tank which is how the PO has it set up and works fine so i have no need to change it.

 

[MIDNIGHT RIDER]

That is a very good no-non-sense set-up.

As for the fuel compatibility of the shut-off valves, don't take me as gospel on this, but it has often been my observation that the better valve is water-compatible and will handle fuel and oils fine; whereas, a specific fuel/oil valve may not be able to withstand the corrosive elements in plain old water.


Having operated many big trucks that were similarly plumbed, there are a couple things I would add to your already fine system.

I would route the line between the tanks to an easily accessible location and install a valve mounted in a bracket, such that when both tanks were FULL, I could close the valve without having to crawl under the truck in my Sunday-go-to-meetin' clothes.

Of course, if so done, the RETURN would have to be in the same tank as the DRAW.

For those not experienced with such a system, the reason for closing the valve between FULL tanks is to prevent the higher elevated tank from over-filling the lower tank and most likely pouring fuel on the ground, such as when having to park with one end of the truck higher than the other ( of course, with side-mounted saddle-tanks, the problem occurs when one side of the truck is higher) .


For the tank outlets, JIC and NPT bulkhead fittings, both 90* and straight, are available with self-sealing O-ring integrated washers; but, I would still double insure the seal with the JB-WELD = better safe than sorry.


A valve TEEed to either of the other valves, situated BETWEEN the tank shut-off valves, would be very handy for those times when one needs a gallon or so of fuel for whatever reason, plus making it more convenient for fuel thieves.

And, should one need to drain either tank, without draining the other, simply close the valve to the tank not being drained and connect a hose to the TEEed valve, and open the valve to the tank to be drained.

Of course, this valve should be securely capped when not in use, both to keep out buggars and to prevent accidental opening.



One could also connect the DRAW-line to the bottom system, instead of drawing out the top.


It all looks good.

 

[sootman73]

could just set up a float and needle type of valve inside the lower tank to keep from overfilling. plus how would you run the valves somewhere else? you couldn't go any higher than the bottom of the upper tank because then you wouldn't have the flow of any fuel to the front tank.....

 

[MIDNIGHT RIDER]

plus how would you run the valves somewhere else? you couldn't go any higher than the bottom of the upper tank because then you wouldn't have the flow of any fuel to the front tank.....

Every truck/situation is different and offers different challenges.

One option, and in this situation = probably better than re-routing the hose, is to utilize a swivel-ended "drive-shaft" to operate one or the other valve from a remote position; this can be either home-made/custom-built, or store-bought.

The extention shaft connects to the valve handle and is mounted in a bracket at the out-board end, with a similar knob/handle attached.

Universal-joint ratchet/socket extensions can be utilized for the extension-rod.

 

[sootman73]

ah got ya. that would make it nicer like if you put a place for a ratchet to hook into in the fuel tank filler location to make it easier while you are filling.....

 

[HammerDown]

"I thought about replacing the factory switch, to much money for something prone to failure."
All due respects, I can appreciate your efforts but > how prone to failure could it be? I'm still on my original switch >since new 1988 and 195,000 miles
If mine fails, I'm pretty sure I'll install another OEM unit...just guess I like factory stuff

Hope I didn't jinx myself here

 

[MIDNIGHT RIDER]

"I thought about replacing the factory switch, to much money for something prone to failure."
All due respects, I can appreciate your efforts but > how prone to failure could it be? I'm still on my original switch >since new 1988 and 195,000 miles
If mine fails, I'm pretty sure I'll install another OEM unit...just guess I like factory stuff

Hope I didn't jinx myself here

Many years ago, I quit counting after the fifth selector-valve quit and left me in the middle of the highway with a load.

The first few were from the Ford parts-counter, and the next ones were a couple different after-market ones.

I never got a warning when one would fail and they always fail in very un-handy places, busy intersections, bad hills, and the like.

I couple times it happened in the road just in front of a fuel-stop, from when I would fill the tanks and select a different tank while sitting at the pumps; there would be just enough fuel in the line to get me right out in the way.

I ran across a bunch of these dead soldiers the other day, while looking for something else, so I do have the evidence to back up my story.


Enough was enough, so I plumbed in ONE manual valve in the DRAW lines and by-passed the return-line to the front tank.

I would run on the front tank until about empty; then, switch to the rear and run on it while the return almost refilled the front tank again.

When the rear was almost empty, and the front almost full again, I would then start looking for a good fuel-stop to refill.


I added a 52-gallon auxilliary and a four-position valve, and still only had a return to the front tank.

I ran this way awhile and later added all new lines, a second four-way valve, and all has been good.

The gauges have been on a SPDT toggle for years and it always works.

The vents of all three tanks are TEEed together, such that should one tank over-fill, the excess simply finds a tank that has room for it.


I know it reads all complicated and mysterious, but is really very simple and completely reliable.

 

[CDX825]

Mine went out last summer going down the highway as well. Switched to the back tank and the truck lost allot of power. I thought I was pulling air so I switched back to the front tank but the fuel gauge level did not change.

Here the valve stuck in the middle keeping the motor energized. I pulled off at the next exit to check the valve and it was so hot I could not touch it. I pulled the fuse for it so it would not catch fire.

I ended up taking a bath in diesel fuel and had to cut up my new fuel lines to bypass the valve.

I'm set on figuring out manual valve setup after that incident so if you guys know of any good manual valves let me know!

 

[The Warden]

"I thought about replacing the factory switch, to much money for something prone to failure."
All due respects, I can appreciate your efforts but > how prone to failure could it be? I'm still on my original switch >since new 1988 and 195,000 miles
If mine fails, I'm pretty sure I'll install another OEM unit...just guess I like factory stuff

Hope I didn't jinx myself here

FWIW you're not alone. I guess some people have had bad luck with the switchover valves, but I'm not one of them. I replaced the valve on my truck once, and it PROBABLY didn't need to be replaced (was trying to diagnose a problem that turned out to be a bad injector pump)...and the one I installed was bought used and has been working fine for over 50K miles now.

Some people prefer to rig their own personalized setup, but OEM's been working well for me; may as well stick with it...

 

[MIDNIGHT RIDER]

I ended up taking a bath in diesel fuel and had to cut up my new fuel lines to bypass the valve.

I have had my share of fuel baths on account of the electric valve.

I once had it happen on the bypass around Atlanta with several days/miles of hauling ahead of me and was nearly strangled on the diesel smell before I could get somewhere to change clothes.

Some people prefer to rig their own personalized setup, but OEM's been working well for me; may as well stick with it...

One simple measure of emergency planning that I would definitely do if I were relying on the electric valve is to install a simple "BYPASS" line from whichever tank-line that was most apt to always have some measure of fuel in it.

Much better to be smart enough to do this in the safety of your own driveway, at your convenience and leisure, than to be laying under the truck in the middle of an intersection and getting drowned with fuel while the greenie with the EPA on speed-dial is making the call.

This can be easily done right at the electric valve with a foot or so of hose and a simple cut-off valve.

NOT if, but when the valve fails, simply open the cut-off valve in the by-pass line and you won't even lose a drop of fuel, probably won't even dust up your Sunday britches.

Fail to heed that bit of advice and someday, somewhere, you will be reminded of this long-forgotten post.

If this is a long-hauler truck, I would also install a power-kill switch in the main wire to the electric valve; it's easier to flip a switch than fight with un-plugging the filthy mess.

And, take the fuel-gauge switching circuit away from the factory set-up, using a plain old SPDT switch instead; thus, one would always know how much fuel they had, regardless of a failed valve.