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Aux Fuel Tank Questions

lil_Blue_Ford

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I’m inclined to say that if the F-150 tank would fit between the frame rails, that might be your ticket
 


ford4wd08

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I’m inclined to say that if the F-150 tank would fit between the frame rails, that might be your ticket
I will still use the aux tank on the flatbed as it is cheaper than trying to replace it with another tool box.

Still think I would like transfer tank on bed for other reasons, for sure a gas rated tank. Better than hauling gas cans to me.

My only concern is adding all the wiring and selector valve etc to another rear tank to get it to work.

I'll have to think on it. I wonder how carb motors did it with dual tanks?

I have an electric pump in front tank, but it is not an efi pump from my understanding not as high pressure.

Could always just pump whatever to main tank and just use it that way.

I've got time to figure this out.
 

JoshT

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Dude, no offense, but I'd ditch the hitch. If you really want to install an aux tank, a "factory" tank back there is the best place for it. Not only will a reciever hitch solve the tank problem, it'll be more useful than a plate mounted pintle hook.

I understand the whole grandpa had it built thing. My 68 F-100 had a hitch built by my dad back 30+ years ago, it was very similar in construction to what you have there except for a reciever instead of pintle on plate. When pulled it out of the weeds and started working on it a few years ago, even he said get a bolt in reciever hitch. He said that if he had the option of buying the recievers like they produce now back then, he would have done that himself. He didn't and had cheap easy access to the metal.

You don't have to spend an arm and a leg for a replacement either. Find one that'll fit in the junk yard. I bought new for the F-100 because local junk yards suck and because of the age it has narrower frame than later models making it harder to find a match. For the Ranger build I found one off a later model Ranger because the frames on that end are practically the same. Then I ended up with a spare on another parts truck.
 

ford4wd08

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Dude, no offense, but I'd ditch the hitch. If you really want to install an aux tank, a "factory" tank back there is the best place for it. Not only will a reciever hitch solve the tank problem, it'll be more useful than a plate mounted pintle hook.

I understand the whole grandpa had it built thing. My 68 F-100 had a hitch built by my dad back 30+ years ago, it was very similar in construction to what you have there except for a reciever instead of pintle on plate. When pulled it out of the weeds and started working on it a few years ago, even he said get a bolt in reciever hitch. He said that if he had the option of buying the recievers like they produce now back then, he would have done that himself. He didn't and had cheap easy access to the metal.

You don't have to spend an arm and a leg for a replacement either. Find one that'll fit in the junk yard. I bought new for the F-100 because local junk yards suck and because of the age it has narrower frame than later models making it harder to find a match. For the Ranger build I found one off a later model Ranger because the frames on that end are practically the same. Then I ended up with a spare on another parts truck.
I'm ditching the pintel hitch and welding in a square reciever hitch when the time comes.

I see no reason to ditch the hitch and the tie backs to the frame. They work, why throw it out?

Go back to my first post. I already HAVE one aux tank. It is mounted below the flatbed. The intent of thread was really how to plumb it vs what it has previously. It won't be getting replaced either.

I might add another rear tank, but not sure it's worth the hassle of my current Aux tank currently offers. Plus I probably don't need to carry 60 plus gallons of gas on the truck. 40ish would probably be plenty.

Transfer tank would be to serve other purposes so I don't have to carry gas cans for toys when on the road.
 
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JoshT

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You posted while I was typing. Do the tanks how you want, that was just my 2 cent up there. I did miss-understand what you were trying to do. By the time I got to the end of the thread I thought that you wanted to add an other aux tank and use the existing one as a transfer tank.

So am I right thinking that you want to keep the main tank, change the way that the aux tank feeds, and possibly add a third transfer/aux tank?

I will still use the aux tank on the flatbed as it is cheaper than trying to replace it with another tool box.

Still think I would like transfer tank on bed for other reasons, for sure a gas rated tank. Better than hauling gas cans to me.

My only concern is adding all the wiring and selector valve etc to another rear tank to get it to work.

I'll have to think on it. I wonder how carb motors did it with dual tanks?

I have an electric pump in front tank, but it is not an efi pump from my understanding not as high pressure.

Could always just pump whatever to main tank and just use it that way.

I've got time to figure this out.
Carbed vehicles typically used a simple switching valve. Either mechanically or electrically operated. Trucks like my old F-100 would have had a simple ball valve mounted down on the floor by the seat to switch tanks, but that was also a mechanical engine drive pump.

My Ranger is an 85 dual tank, so similar vintage, but EFI. The Ranger has an electrical switch on the dash that controlls the tank seelction boy powering the selected in tank, low pressure pump. There is a filter/reservior that accepts feeds and returns to each tank, it probably has check valves to prevent cross feed, and a high pressure pump that pushes fuel from there to the engine. The reservior is necessary to keep the high pressure pump supplied when switching tanks. The dash switch also switches the gauge between the main and aux sender.

Your carbed truck would not have needed the reservior and it appears that they used a switching valve very similar to what @bobbywalter posted above. Based on pictures of the valve and sender for your truck, it appears that even the carbed engine would have had a fuel return port which is surprising to me. If I had to guess, a dual tank version off your truck wouldsend power to the selected tank's pump and change the sswitching valve via a single switch on the dash.

If you can add a low pressure pump to the aux tanks (in tank or inline), a valve like the one that Bobby posted would probably be your best option for in cab tank switching. It's got two sides (one for feed, one for return) but if you don't have a return then you don't have to use both. Simple toggle switch on the dash will handle tank selection and a relay for switching between the pumps. For the second aux tank, add another valve plumbed into the first and nother relay to switch the power between the two aux tank pumps. . If I were doing it I'd have one switch/valve to go between main and aux tanks, a second switch/valve plumbed into the first for aux1 or aux 2.

My crude stick figure sketch of how I'd do it:

Untitled.png

Having a sender for the gauge wouldn't be quite as easy, but could be done using the same switches and some relays. Being carbed, I probably wouldn't bother. Start out on the aux tanks, the engine will let you know when they're getting empty, then switch to the main and start watching the gauge.

Most of the posts I've come across about dual tank trucks is from people having issues with the reservior, so I wouldn't mind getting away from it. I also don't care for the potential failure point of the inline, frame mounted, high pressure pump. If I ever need to rebuild the fuel system in my dual tank Ranger I'll be ditching the reservior and inline high pressure pump. I'll go to high pressure pumps in each tank, the valve that Bobby posted, and a cartridge style fuel filter.
 

lil_Blue_Ford

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I’d be curious to know if these trucks all came wired for dual tanks whether they got it or not. It’s certainly possible. I’ve seen Rangers and Bronco II s with wiring for premium sound for the stereo and such even if they didn’t come with it. Easier to build every chassis with one wiring harness no matter what the options so adding a dual tank may not be overly difficult
 

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If you have a Return fuel system it complicates dual tank systems but just by the plumbing of fuel lines, you can buy 6 port fuel line electric valves, or just use 2 regular 3 port valves

And the a dash switch to activate the 6 port valve and to switch fuel gauge to that tank's sender

Just 1 12volt wire to 6 port switch and 1 wire to AUX tank sender, from Cab

I would wire the AUX tanks fuel pump to the 12volt power at the Valve so it only runs when using that tank, the main tanks pump can be left on, doesn't hurt anything as long a tank has some fuel left in it
But if it worried you, you could install a 5 pole relay by the valve that would switch power to pumps when Valve was activated


If you just want a storage tank then not sure why you would need to pump gas from that tank to the main tank while driving?
Better to fill up both tanks at last place available before heading out to no gas land, lol
 

ford4wd08

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You posted while I was typing. Do the tanks how you want, that was just my 2 cent up there. I did miss-understand what you were trying to do. By the time I got to the end of the thread I thought that you wanted to add an other aux tank and use the existing one as a transfer tank.

So am I right thinking that you want to keep the main tank, change the way that the aux tank feeds, and possibly add a third transfer/aux tank?



Carbed vehicles typically used a simple switching valve. Either mechanically or electrically operated. Trucks like my old F-100 would have had a simple ball valve mounted down on the floor by the seat to switch tanks, but that was also a mechanical engine drive pump.

My Ranger is an 85 dual tank, so similar vintage, but EFI. The Ranger has an electrical switch on the dash that controlls the tank seelction boy powering the selected in tank, low pressure pump. There is a filter/reservior that accepts feeds and returns to each tank, it probably has check valves to prevent cross feed, and a high pressure pump that pushes fuel from there to the engine. The reservior is necessary to keep the high pressure pump supplied when switching tanks. The dash switch also switches the gauge between the main and aux sender.

Your carbed truck would not have needed the reservior and it appears that they used a switching valve very similar to what @bobbywalter posted above. Based on pictures of the valve and sender for your truck, it appears that even the carbed engine would have had a fuel return port which is surprising to me. If I had to guess, a dual tank version off your truck wouldsend power to the selected tank's pump and change the sswitching valve via a single switch on the dash.

If you can add a low pressure pump to the aux tanks (in tank or inline), a valve like the one that Bobby posted would probably be your best option for in cab tank switching. It's got two sides (one for feed, one for return) but if you don't have a return then you don't have to use both. Simple toggle switch on the dash will handle tank selection and a relay for switching between the pumps. For the second aux tank, add another valve plumbed into the first and nother relay to switch the power between the two aux tank pumps. . If I were doing it I'd have one switch/valve to go between main and aux tanks, a second switch/valve plumbed into the first for aux1 or aux 2.

My crude stick figure sketch of how I'd do it:

View attachment 83174

Having a sender for the gauge wouldn't be quite as easy, but could be done using the same switches and some relays. Being carbed, I probably wouldn't bother. Start out on the aux tanks, the engine will let you know when they're getting empty, then switch to the main and start watching the gauge.

Most of the posts I've come across about dual tank trucks is from people having issues with the reservior, so I wouldn't mind getting away from it. I also don't care for the potential failure point of the inline, frame mounted, high pressure pump. If I ever need to rebuild the fuel system in my dual tank Ranger I'll be ditching the reservior and inline high pressure pump. I'll go to high pressure pumps in each tank, the valve that Bobby posted, and a cartridge style fuel filter.
No issue, I got a little of track myself.

Now that you say that I forgot that Ford used two pumps on the early EFI rigs in the 80's.

The hot fuel option was common on 460's in the south with AC and all. It has an in tank pump which is probably the same as the low pressure pump EFI used in the tank and no reservoir. It pumps to the carb through a little small contraption that has an orifice in it to my understanding and has a return line. It is supposed to always recirculate cool fuel from the tank and it does work well. Never had a vapor lock issue on this truck.

Due to keep that option and run two electric pumps I would have to run to solenoid or something like you mentioned.

I do like the ability to have a backup pump for the aux in case the one in tank failed (which happens too often anymore on aftermarket replacements).

Yeah tank on the bed would only be transfer tank. Too much work, etc to try and make it for gas as it is a different class than diesel, but can be hauled that way in a gas approved transfer tank.

I'll just have to think this all through.
 

ford4wd08

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If you have a Return fuel system it complicates dual tank systems but just by the plumbing of fuel lines, you can buy 6 port fuel line electric valves, or just use 2 regular 3 port valves

And the a dash switch to activate the 6 port valve and to switch fuel gauge to that tank's sender

Just 1 12volt wire to 6 port switch and 1 wire to AUX tank sender, from Cab

I would wire the AUX tanks fuel pump to the 12volt power at the Valve so it only runs when using that tank, the main tanks pump can be left on, doesn't hurt anything as long a tank has some fuel left in it
But if it worried you, you could install a 5 pole relay by the valve that would switch power to pumps when Valve was activated


If you just want a storage tank then not sure why you would need to pump gas from that tank to the main tank while driving?
Better to fill up both tanks at last place available before heading out to no gas land, lol
I already have AUX tank, I added in Transfer tank to the conversation, but I'll just leave it out for toys only.

The only thing it did when new was pump gas from AUX tank to main tank filler neck with frame mounted electric pump and a switch. Which, technically worked.
 

JoshT

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The hot fuel option was common on 460's in the south with AC and all. It has an in tank pump which is probably the same as the low pressure pump EFI used in the tank and no reservoir. It pumps to the carb through a little small contraption that has an orifice in it to my understanding and has a return line. It is supposed to always recirculate cool fuel from the tank and it does work well. Never had a vapor lock issue on this truck.

Due to keep that option and run two electric pumps I would have to run to solenoid or something like you mentioned.

I do like the ability to have a backup pump for the aux in case the one in tank failed (which happens too often anymore on aftermarket replacements).
Yeah, in that case the valve Bobby posted would be perfect. Put it in line between the tanks and the orifice valve. It has two sides, one for inlet and the other for return. Each side has three ports, one port to each tank and one port to the engine/orifice valve. You shouldn't need a reservior, there is plenty of reserve in the carburetor bowls for the fuel pump change over. You would need to add a fuel return port and pump (inline or intank) for the aux tank.

For the pumps. I'm attaching a file that shows how to wire that valve. Don't recall where I found it, but I saved it incase I use one myself. In the photo it shows how to wire wire in the two pumps. I'd change it up a little though. Instead of wiring each pump through the DPDT switch, I'd pull power from the truck's original fuel pump wire. I'd cut the wire going to the main pump and install a 30/40 amp NO/NC automotive mini relay, that's the kind with 5 terminals. Attach the hot side of that wire from the fuse box to the common terminal (30) of the relay. The other half of that wire to the Normally Open contact (87a), then wire the aux tank pump into the Normally Closed contact (87). From the diagram of the pump attach the auxiliary pump wire to terminal 85 or 86 and the other to a ground.

Function of that would be when DPDT switch is in main the valve is switched to main and the relay is open sending power to the main tank pump. When you switch to aux tank, the valve switches over and a signal is sent to close the relay and power is changed to aux tank pump. Since you tied into the original fuel pump power, either pump would only get power when the truck is turned on.

Introduction to Automotive Relays | GTSparkplugs


If you did want to add a sending unit to the aux and wire it up to the dash gauge, that valve Bobby posted can even help with that. It's got it a switch for that built in, just got to get the right sending unit for the tank and wire the valve between the tanks and the gauge. Like I said I wouldn't bother with the sending unit, just empty the aux first and switch over to the main for the gauge.
 
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ford4wd08

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Yeah, in that case the valve Bobby posted would be perfect. Put it in line between the tanks and the orifice valve. It has two sides, one for inlet and the other for return. Each side has three ports, one port to each tank and one port to the engine/orifice valve. You shouldn't need a reservior, there is plenty of reserve in the carburetor bowls for the fuel pump change over. Wire it so that flipping the switch changes the valve and energizes pump for the selected tank. You would need to add a fuel return port and pump (inline or intank) for the aux tank.

If you did want to add a sending unit to the aux and wire it up to the dash gauge, that valve Bobby posted can even help with that. It's got it a switch for that built in, just got to get the right sending unit for the tank and wire the valve between the tanks and the gauge. Like I said I wouldn't bother with the sending unit, just empty the aux first and switch over to the main for the gauge.
I agree. I think I can make that happen. I would likely go with a frame mounted pump for ease of use, install for AUX tank. Might even carry a spare just in case.

This rig will be pulling a camper at some point and I don't want to be stranded anywhere pulling a camper because of a fuel pump if I can help it.
 

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