Fuel tank selector not working anymore

[lindstromjd]

This is on my '87 with a 6.9... I can't say exactly what I did to get the tank selector to stop working, but when I first got the truck, in order to get it running, I had to use an '86 fuel pickup/sending unit for the front tank. The gauge never worked right after I did that (either read 0, or pegged itself after clicking a bunch of times). I think the fuel pickup/sending units are different styles from '86 to '87? I also changed over the dash and gauges from the '87 to a '91 because the '87 ones weren't working right and I liked the way the '91 looks better.

I fixed my front sending unit just tonight, so the right one for the '87 is back on and I think it's working right now. Is there any connection between the different dash/gauges and making the selector valve not work? I'm almost positive that the selector used to work, or at least it would show me different readings on the gauge when I flipped the switch, before i put the '86 sending unit in. I did have the rear tank filled completely, and was using it for a while until the gauge started acting screwy, so I wasn't sure how much was still in the tank. I switched back to the front just in case, and I saw tonight that the rear tank has about 1/2 tank of fuel in it.

I guess what I'm asking is if it's something I did by swapping in different parts, or if it's just the valve going bad?

 

[Knuckledragger]

I have had 2 of these tank valves go bad on my 85s. Doubt that the senders or gauge problems have anything to do with it. Does fuel leak from the valve body? That is when I knew that the valve had gone bad. Otherwise it performed fine.

I don't know if there was a change after 86, but at some point, the ohm rating for the gauges changed. So your 86 sender may not be speaking the same language the 87 gauge is hearing.

 

[RLDSL]

You did nothing to it, it's 24 years old, and a wonder it made it that long. Unfortunately the replacements aren't made as well.
Now would be a great time to swap it out for a pair of manual valves

 

[boxathey]

do you have any info on the manual valves. Are they just full port stainless ball valves you would get at a local hardware store, with some hose barbs?

 

[lindstromjd]

About those manual valves... has anyone done a write up on them?

 

[lotzagoodstuff]

I don't want to hijack this thread, but I do have a line on a double three way ball valve with a long shaft and ball valve handle. It's actually a stock piece on many class 8 trucks and should be really easy to use. If there's any interest, I'll get a part number and pricing, it's a super nice brass piece that should last as it's designed for use with twin diesel tanks. I have one in stock, just waiting for mine to fail as I'm not putting another electronic selector valve in my truck if/when it fails.

Let me know if anybody has any interest.

 

[bike-maker]

That the one made by Parker? I was thinking about using one of those when I switched over to the manual valves, but I heard they have a higher failure rate - something to the effect of them have enough resistance that they brake the handles off? But my main reason for running 2 separate valves is it allows me to transfer fuel from 1 tank to the other.

 

[lotzagoodstuff]

That the one made by Parker? I was thinking about using one of those when I switched over to the manual valves, but I heard they have a higher failure rate - something to the effect of them have enough resistance that they brake the handles off? But my main reason for running 2 separate valves is it allows me to transfer fuel from 1 tank to the other.

Yes Mike, it's a double version of a Parker 533 series 3 way valve. I don't want to see the guy who broke the handle as it's pretty beefy, and the shaft is 3/8". Just wondering: why do you want to transfer fuel from one tank to another? But just in case: Parker makes a four way valve, look up a XV540P and you should see it.

Good luck, let me know if I can help you find anything from Parker.

 

[bike-maker]

I've used my fuel transferring capabilities only a couple times. Once when I drained one of the tanks to remove it, and once when the high school kid at the gas station overfilled my tank to the point that it was dumping out of the vent tube.
It's one of those nice to have just in case kinda things.

 

[MIDNIGHT RIDER]

The dual-control manual valves that are capable of switching both DRAW and RETURN on one shank/handle are highly prone to the shank snapping, either between the two ball-valves, or just below the handle.

In theory, they seem like a good idea; in real practice = not so good.

I prefer two separate manual valves for the same reasons that bikemaker mentioned.

One thing I will point out about ALL manual ball-type valves :

It is becoming increasingly harder to find genuine stainless-ball valves; most are some sort of plastic; I am talking about the actual BALL inside the valve, not the brass valve body.

After continuous contact with fuel, the plastic swells, making the valve harder and harder to turn, until the plastic becomes so tight that the stem simply cannot turn it anymore and snaps off.

This takes several years to happen, but it sooner or later does occur.

When the handle begins to have resistance to operating the valve, that is your warning to order another valve; failure to heed that warning will result in that handle snapping off in your hand at the most inopportune place.



For what it's worth, I have never yet seen any sort of tank selection valve on a road-tractor; every one I have ever driven/seen has had a simple cross-over equalizer from tank-bottom to tank-bottom, with a plain old cut-off valve at each tank for isolation purposes and to prevent excess fuel from pouring out the vent of the lowest tank when leaving the truck parked on a sidling incline.

 

[lotzagoodstuff]

The Parker 600 series style diversion valves use chrome plated ball and PTFE seals. The dual version has a 3/8" stem and a very heavy duty handle. The forging encapsulates both valves completely, and to stem seal is very beefy, and rebuildable. Freightliner uses a pile of these, they are very durable. And there is a three position that actually lets the feed draw from both sides, and could be used to transfer fuel with a little thought.

If you are really worried about breaking a handle on a ball valve: take the paddle style handle off and put an oval handle on it. Ball valve handles break because of the side load people put on the standard handle. An oval handle puts significantly less side loading on them.

Have a look at this link if you are interested in more information.

http://www.parker.com/portal/site/P...tcatid=5257&vgnextcat=BRASS+BALL+VALVES&Wtky=

 

[gunz]

Why not just plumb the tanks together and not bother with a switch. Just one gauge on the front tank and let the rear tank feed the front. Just an idea.

 

[franklin2]

We have had several threads on this in the past months. Not complaining, but I am trying to zero in on the best solution for the dual tank fuel system. Knock on wood, my factory system is still working so far.

We talked about tying the fuel tanks together. This is not easily done. Welding fittings on the bottom of both tanks is not readily available to everyone, and takes some skill to do yourself. That's the only way you are going to be able to tie them together like the big semi's. And being the back tank is a little higher than the front, I would fill the rear tank first, then the front. I can see the front tank being filled, and then the rear tank being topped off, overflowing the front tank.

The talk in this thread is manual valves. For the ones that have done it I have some questions;

Where do you mount the valves? I would assume in the cab through the floorboard somewhere? Getting out of the truck on a long trip to change tanks would be a deal breaker for me. Or getting out in the pouring down snow to do the same thing. If they where mounted in the cab;

Where and how did you do it? Are there valves made with long stems that will poke through the cab floor? I am assuming you also brought the sending unit wiring back up into the cab somehow with a manual switch to switch the fuel gauge around?

The other solution was to use a transfer pump to transfer the fuel from the back tank to the front, the front tank being the only one hooked to the engine and having a sending unit. I was worried about this system overfilling the front tank, but the poster that brought up this idea said you could tie the vent systems together, and any overflow would go back to the rear tank. I think this would work and is a viable solution. Everyone on this board should be running the homemade 1/2" tank vent systems on their truck, and this would be easy to tie together and would definitely handle the overflow of fuel.

 

[MIDNIGHT RIDER]

franklin2,

The standard manual tank-selector valves have a stem length that is ideal for mounting the actual valve under the floor with the handle inside the cab.

They also offer the valves with a somewhat longer stem, but it is much too long for our purposes and much more likely to break.

I mounted my two valves in the area of the floor between the driver's seat and door.

The valves are underneath the floor with the operating handles inside the cab.

I made a 1/4"-thick aluminum plate that is screwed to the floor, over the carpet.

The valve-stems protude through this aluminum plate, making for a neat finished appearance; the SPDT toggle-switch that controls the gauges also pokes through this plate, with the actual switch being underneath the floor.


Simple brackets will need be fabricated that the valve-bodies attach to.

These brackets bolt to the floor flange that runs lengthwise underneath the floor.




As for adding outlets to the bottom of the fuel-tanks, although not at all necessary when using the manual valves, this is easily accomplished by using JIC bulk-head fittings that are made for this purpose.

These bulk-head fittings have a long threaded shank with a wide shoulder.

A seal goes against this shoulder; the threaded shank passes through a hole drilled through the tank; another seal goes over the shank inside the tank; finally a washer and large nut on the threaded shank tightens the fitting to a leak-free seal.

I have successfully used these fittings in tanks where I had to pass a string through the fitting and out through the fuel-inlet, threading the internal seal, then the flat-washer, then the nut onto the string such that they follow the string to the threaded shank.

Not easy, but very possible to accomplish.


It is good to have drain-valves in the bottom of tanks, so long as their presence is concealed from fuel thieves.