Thinking Bout The Fuel Tank Switch over Valve.

[icanfixall]

Today during my 200 mile road trip with the radio off listening to the engine sing to me I got to thinking about changing the fuel tank switch over valve. Taking it out of the fuel system all together. I felt we could run two seperate electric fuel pumps plumbed into the fuel system. That way we could have a backup fuel pump working all the time. With some thought I felt we could run the power feed thru the dash switch and that could sent power to a relays just because I don't know if the dash switch could take the load of an electric fuel pump. Both pumps would need to feed fuel into a Tee at the main feed line to the engine with check valves. Same with the returns. I'm no expert but what do you think bout this. Run with it if you want.. I'm interested in what others think. The way I see it we no longer need to worry bout a fuel tank switch over valve and the money saved more than pays for the redundancy of having 2 electric pumps. Now neither of the pump will work at the same time. When we change from the front to the rear tank the dash switch changes the pumps power thru relays. Unless we find out the dash switch can handle the load..

 

[mjs2011]

You would still need a valve for the return lines. Otherwise, how does the return furl change which tank it is going to.

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[laserjock]

I was thinking the same thing. Could possibly use a latching solenoid 3way valve. They require power the switch but very little to hold them open (typically a big and small coil). I've thought about replacing the fsv with a pair of them but haven't found one I'm happy with. Then it's just buying a relay with an extra set of poles to run the fuel sender wires through. So essentially a double pole double throw relay would switch the valves and change which sender the gauge is reading.

I'd probably set it so that the valves are normally open to the front tank (its bigger) so the coils would only be energized for using the rear tank. It really wouldn't matter. If you do key on power to the system, the valves would flip as soon as the key was pushed to run.

Now to Gary's point of dual pumps. It's certainly an option. I'd probably run the lines to near the front and put the Ts under the hood. Just easier to get to. I would also probably put check valves after the pumps so that you don't push fuel backwards from one tank to the other. Some pumps will allow that if they don't have an internal check of some sort.

As you can see, I've spent a little time thinking about this one.


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[OLDBULL8]

Sure you can. Using a two position double pole switch. "DPDT". UP--On Down--On. With a relay powered by the FSS circuit, that would supply fused battery power to the switch. The swiitch would power two relays, relay one=front tank and solenoid, relay two=rear tank and solenoid. Switch in the up position = front tank, switch in down position = rear tank and solenoid. Each pump would have it's own suction from a tank. The return fuel would tee off to a solenoid, each solenoid would return fuel to it's proper tank, the solenoid that is de-energized would block fuel to the other tank.

2-Relay's-- three pole
2-Solenoids
1- DPDT or a DPTP Center would be OFF position.

The diagram won't copy as typed, have to shift R,S and P over to the O, also the o pilot lite under the O
B+
o
|| 15A Fuse or Resettable circuit breaker
o B-
| |
= FSS |
| |
| S1 R1 |
|-----------o/o------------------O-----|
| |------0-----| Pilot Lite in Cab
| S2 R2 |
|-----------o/o------------------O-----|
| |------0-----| Pilot Lite in Cab
| R1 P1 |
|-----------l l---------------------O----|
| |
| R1 S1-----|
|-----------l l--------------------O-----|
| |
| R2 P2 |
|------------l l--------------------O----|
| |
| R2 S2 |
|------------l l--------------------O----|

 

[The Warden]

FWIW, according to my 1984 shop manual, the 460 dual-tank trucks were set up like this from the factory. Each tank has an in-tank pump (integral to the fuel sending unit), and the in-dash switch activates one or the other pumps. The fuel switchover valve was a dual-port, allowing for a return line, and was switched by fuel pressure in the input lines. I don't remember how the gauge switchover was handled...but, if anyone's interested, I can dig out the manual and post more details when I have time (if that ever happens )...

 

[ifrythings]

FWIW, according to my 1984 shop manual, the 460 dual-tank trucks were set up like this from the factory. Each tank has an in-tank pump (integral to the fuel sending unit), and the in-dash switch activates one or the other pumps. The fuel switchover valve was a dual-port, allowing for a return line, and was switched by fuel pressure in the input lines. I don't remember how the gauge switchover was handled...but, if anyone's interested, I can dig out the manual and post more details when I have time (if that ever happens )...

On the gassers, the dash switch selected the sending unit and in tank fuel pump(low pressure, low power) and on EFI units they added a booster pump(high pressure) with a relay that the ECM turned on and off, on the diesel's the FSV does the tank selecting and sending unit selecting and the dash switch is used to switch the polarity to the FSV making the internal motor move 2 sets of valves and the sending unit switch.

 

[tbrumm]

Today during my 200 mile road trip with the radio off listening to the engine sing to me . ..

Gary - I do this too. I turn the radio off and listen to the soothing sound of a well running diesel! The Wife thinks I am nuts and wants the radio on.

 

[laserjock]

Now there is an intereting idea. If you chose a pump that put out enough pressure you could litteraly set it up like a gasser. Just use a hydraulic valve that would be plumbed much like an air system only using the fuel pressure. Or if you have onboard air, pnematic would completely be the way to go. Only problem then is if the air goes out you are stuck on which ever tank you are on. A well plumbed system and a paintball CO2 can could last a really long time though. It would take next to nothing to actuate the valves. I did that on a work project a few years ago. Used those belt clip CO2 air tool gadgets to drive the pneumatics on a device out in the field.

Hmmm.

 

[theguruat12]

Sure you can. Using a two position double pole switch. "DPDT". UP--On Down--On. With a relay powered by the FSS circuit, that would supply fused battery power to the switch. The swiitch would power two relays, relay one=front tank and solenoid, relay two=rear tank and solenoid. Switch in the up position = front tank, switch in down position = rear tank and solenoid. Each pump would have it's own suction from a tank. The return fuel would tee off to a solenoid, each solenoid would return fuel to it's proper tank, the solenoid that is de-energized would block fuel to the other tank.

2-Relay's-- three pole
2-Solenoids
1- DPDT or a DPTP Center would be OFF position.

The diagram won't copy as typed, have to shift R,S and P over to the O, also the o pilot lite under the O
B+
o
|| 15A Fuse or Resettable circuit breaker
o B-
| |
= FSS |
| |
| S1 R1 |
|-----------o/o------------------O-----|
| |------0-----| Pilot Lite in Cab
| S2 R2 |
|-----------o/o------------------O-----|
| |------0-----| Pilot Lite in Cab
| R1 P1 |
|-----------l l---------------------O----|
| |
| R1 S1-----|
|-----------l l--------------------O-----|
| |
| R2 P2 |
|------------l l--------------------O----|
| |
| R2 S2 |
|------------l l--------------------O----|

I think Oldbull has the right idea with just using two solenoid open/shut valves rather than the one finicky switching valve to block/open each return line. I'm sure the dash switch could handle running a bosch relay (that's all it would have to run, the power for a solenoid could run off of the same relay that does the fuel pump itself). I like the idea of redundant pumps, especially because if I did this, the pumps would be right next to each other, so even if the tank I'm using fails, and the other is empty, it only takes 5 minutes and a screwdriver to swap the other pump in.

 

[OLDBULL8]

As I stated before in a previous post, this can be done, but it could become awfully expensive and a lot of work. So, instead of that, why not this as a spare part behind the rear seat, for a meer $76 bucs. It's a direct replacement, made by Pollack, the only maker of these valves. http://www.autozone.com/autozone/pa...-8ve9x?itemIdentifier=518461&_requestid=92988. These FSV on a dual tank diesel is mounted on the frame rail, some are mounted Verticle, some are mounted horizontal. The older FSV's have a different electrical connector than these, hence the new connector comes with the new style connector, wire color code is the same, just have to splice in the new one. The switch that comes with it is NOT necessary to change.
You can get this one without the switch or pigtail, but the pigtail has to be bought seperate. FSV only for $63. http://www.autozone.com/autozone/pa...iwqk7Z8ve9x?itemIdentifier=18894_686940_5320_ IIRC the connector is $13.

OR, you can go to a Ford dealer and purchase the same FSV made by Pollack for $260, your choice.
Advance, CarQest, O'Rielly or any other Auto store may stock the same FSV, do your own search.

 

[laserjock]

As I stated before in a previous post, this can be done, but it could become awfully expensive and a lot of work. So, instead of that, why not this as a spare part behind the rear seat, for a meer $76 bucs. It's a direct replacement, made by Pollack, the only maker of these valves. http://www.autozone.com/autozone/pa...-8ve9x?itemIdentifier=518461&_requestid=92988. These FSV on a dual tank diesel is mounted on the frame rail, some are mounted Verticle, some are mounted horizontal. The older FSV's have a different electrical connector than these, hence the new connector comes with the new style connector, wire color code is the same, just have to splice in the new one. The switch that comes with it is NOT necessary to change.
You can get this one without the switch or pigtail, but the pigtail has to be bought seperate. FSV only for $63. http://www.autozone.com/autozone/pa...iwqk7Z8ve9x?itemIdentifier=18894_686940_5320_ IIRC the connector is $13.

OR, you can go to a Ford dealer and purchase the same FSV made by Pollack for $260, your choice.
Advance, CarQest, O'Rielly or any other Auto store may stock the same FSV, do your own search.

Yeah, fair point but where is the cool factor in that....

Who wants the reasonable straight forward solution to a problem when for twice the price and complications, you could have a cool Rube Goldberg solution??

 

[oworm]

As I stated before in a previous post, this can be done, but it could become awfully expensive and a lot of work. So, instead of that, why not this as a spare part behind the rear seat, for a meer $76 bucs. It's a direct replacement, made by Pollack, the only maker of these valves. http://www.autozone.com/autozone/pa...-8ve9x?itemIdentifier=518461&_requestid=92988. These FSV on a dual tank diesel is mounted on the frame rail, some are mounted Verticle, some are mounted horizontal. The older FSV's have a different electrical connector than these, hence the new connector comes with the new style connector, wire color code is the same, just have to splice in the new one. The switch that comes with it is NOT necessary to change.
You can get this one without the switch or pigtail, but the pigtail has to be bought seperate. FSV only for $63. http://www.autozone.com/autozone/pa...iwqk7Z8ve9x?itemIdentifier=18894_686940_5320_ IIRC the connector is $13.

OR, you can go to a Ford dealer and purchase the same FSV made by Pollack for $260, your choice.
Advance, CarQest, O'Rielly or any other Auto store may stock the same FSV, do your own search.

Thanks for this. I've been running around on one tank for a year because of a faulty fsv

 

[franklin2]

FWIW, according to my 1984 shop manual, the 460 dual-tank trucks were set up like this from the factory. Each tank has an in-tank pump (integral to the fuel sending unit), and the in-dash switch activates one or the other pumps. The fuel switchover valve was a dual-port, allowing for a return line, and was switched by fuel pressure in the input lines. I don't remember how the gauge switchover was handled...but, if anyone's interested, I can dig out the manual and post more details when I have time (if that ever happens )...

I believe you will find most of the older 460's had the exact same finicky valve and the exact same setup as the diesel, except for the in-tank pumps. I believe you are correct though, later on they did use a valve that worked off of the fuel pump pressure, but these would probably be the efi trucks which would have had the higher pressure pumps in each tank. The later smaller engined efi trucks also used a FSV with no wires going to it, fuel pump pressure worked it back and forth.

 

[typ4]

my efi 460, not any more , dually has 2 low pressure tank pumps and a high pressure mounted on the frame rail after the switch canister, which is fuel operated and uses a diaphragm arrangement to select, I will be using this setup temporarily at least to run the diesel with a bypass tee to regulate pressure to the transfer pump.








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[ZWilson07]

Interesting thread.

I will definately be following along.

Just more excuses to spend more money on my rig

I think when I get another IDI I might just run one large tank and make it easy and not have to ever worry about anything. But then where is the fun in all that lol. For my 90 I plan on keeping it as close to "factory stock" as possible, but just a few improvements on factory setups to make them better and safer such as headlight wiring, maybe electric fuel pump, etc.