2nd Gen Non-Engine/Transmission tank return?

[Ahopper]

i am putting in a aux tank in the bed with a gravity feed. i noticed on top of the fuel pickup/sender that ther is an extra barb with a cover on it not going to anything. can i use this to drain my aux tank to my regular tank? thanks!

 

[JLandry]

i am putting in a aux tank in the bed with a gravity feed. i noticed on top of the fuel pickup/sender that ther is an extra barb with a cover on it not going to anything. can i use this to drain my aux tank to my regular tank? thanks!

If you're referring to the rollover vent valve on the top of the Dodge main tank, then I don't think that would be a good idea for a couple of reasons...

1. That's a check valve and would likely have enough restriction in it to prevent fuel flow via gravity feed.



2. The rollover valve enters inside the the fuel pickup module, and thus fuel entering through this location would be bypassing the fuel filter screen (at the bottom of the module).​

That said, you DO need to run a 1/4" ID fuel line as a vent line from that rollover valve barb to a location at or above the top of your aux tank. This will prevent fuel from seeping out of the rollover valve when the main tank gets completely filled from gravity feed to the main tank filler neck.



Regards,



John L.

 

[DMcLeod]

The barb you're referring to may be an auxilliary port (like on my 01). This is not part of the rollover valve. My espar preheater draws fuel from this port. I've never had the fuel pickup/sender out, so I don't know first hand what it looks like internal to the tank, but it does draw fuel from low in the tank. I would think it may work for ya.

 

[Ahopper]

i hooked the fuel hose on it and blew through it and could hear the air bubbling. does anyone have any other ideas? will this work or should i find another way to get it in the tank?

 

[Joe G.]

My '95 service manual shows the port that is covered with a little cover as an auxillary input. I used it for a while as a connection for my aux tank. I've changed the setup since then.

 

[Ahopper]

joe, what do you use now for your aux tank? is that port not ok to use? is it to slow?

 

[Joe G.]

That port works fine. The problem was with the gravity feed. I found that if my main tank was full or almost full the pressure from the gravity feed would cause a very small leak in the pressure relief valve when the tank plus the filler neck was full. I kept getting a very small spot of diesel on my garage floor. I eventually traced it to the pressure relief valve on the fuel tank module. If the tank was lower than full this leak didn't happen.



Then I realized that I already had a line to the fuel tank that input fuel to it. That is the return line from the injection pump. So why am I messing around with transferring fuel from the aux tank to the main tank which requires some plumbing changes at the main tank? I now have a tank selection valve mounted on the frame near the engine. It selects either tank as input to the fuel heater/pre-filter assembly. All fuel is returned to the main tank. The plumbing is pretty simple. Fuel hose from the aux tank to the valve which is spliced into the fuel hose from the steel line to the fuel heater/pre-filter assembly. I do have a way to easily disconnect the aux tank if I want to remove it. The fuel transfer rate from the aux tank is a lot faster than I expected. I designed a simple controller to turn the tank selection valve to the aux tank when the main tank is low and turn it back to the main tank when the main tank is full or the aux tank is empty.

 

[Ahopper]

joe, you wouldny have part #`s or pictures would you? thanks for the help

 

[Joe G.]

No I don't. No pictures. I went into NAPA and asked for a tank selection valve that only switch one line in stead of both the supply and the return line. He asked what make and year etc etc. I told him anyone would do since I'm using it for a modification. He got one from stock. I think it is for a Chevy but I'm not sure. I can take some pictures of my installation if you will email me for them. My aux tank is removable for when I need the entire bed for hauling something.

 

[bwromine]

That is kind of what I did with mine also. I installed a selector valve and a fuel pump from oreilly's and put a toggle switch in my cab by the a pillar. I had a 1/4" pipe welded on the filler neck and ran a hose from it to the selector valve and which is wired to toggle switch. Going down the road I just flip the switch and pump from aux tank into the main tank. I had this same setup on my 95 and when I sold it I pulled tank, switch, pump and valve off and installed it on my 02. No problems what-so-ever.

 

[Joe G.]

That is kind of what I did with mine also. I installed a selector valve and a fuel pump from oreilly's and put a toggle switch in my cab by the a pillar. I had a 1/4" pipe welded on the filler neck and ran a hose from it to the selector valve and which is wired to toggle switch. Going down the road I just flip the switch and pump from aux tank into the main tank. I had this same setup on my 95 and when I sold it I pulled tank, switch, pump and valve off and installed it on my 02. No problems what-so-ever.

The way I did it is fundamentally different. I don't use an extra pump and no mods to the stock tank are necessary. My tank selection valve selects the aux tank as input to the fuel system so the stock lift pump is doing the fuel transfer by input from the aux tank and return to the stock tank. The only mods to my stock tank are vents for the bumps to the stock vent tube so I can get more fuel in it.

 

[rweis]

I have tried several different gravity feeds from bed tank to OEM tank. Here is what I settled on and why.



1st attempt: Feed bed tank to tank filler line with Northern Tools "gravity feed" universal valve. Problem, the Northern Tools valve has a float in it and the opening that the float sits against is about 1/16" and will not feed enough fuel to make up unloaded engine operation, much less pulling my RV.



2nd attempt: Made a tank filler line adapter with a firewall fuel pass through fitting. Problem, tank filler line is round and firewall passthrough is flat. Tried several ways to seal the round against the flat and never got a good seal.



3rd attempt: Brazed (not soldered) a 1/4" copper pipe into a tank filler line adapter to get a full flow fuel from the bed tank into the OEM tank and totally sealed. Works great with AN-6 line. The 3/8" id of the fuel line is smaller than the 1/4" od of the copper pipe but you can lube the copper pipe and get a good 1" of fuel tubing pushed up onto the copper pipe for hose clamping.



Now, to the tank cannister.



I tried to vent the OEM tank through the overflow valve up to the bed tank. Did not work well because the OEM tank overflow vent willl not pass enough air around the roll over valve to vent enough so the bed tank can refill the OEM tank at more than a trickle.



I looked at the OEM secondary return fitting on the OEM tank. It is a about 3/8" diameter fitting on top of the canister and on my 02. It only goes int the OEM tank and does not have any extensions into the OEM tank. I did not use this because it is sort of short (1/2" maybe) to be able to get a hose clamp around it and trust it.



I installed a DrawStraw II some time ago. The DS II has a second port in the head of the DS II. I put in a 1/4" barbed fitting and use that as my vent line back to the bed tank. One thing to know about the DS II fittings is the DS II head is round with the 1/4" threading NOT perpendicular to the round shape. This means you have to be sure you get a really good LONG threaded fitting (not long fitting, long threads) to be able to seal the threads adequately before the wrench part of the fitting starts to mechanically interfere with the DS II head and prevents you from further tightening of the fitting into the DS II head.



(put your finger across the top of a soda can not perpendicular to the center, but offset about 1" from the center but straight across. You see the threads toward the center start sooner than the threads toward the outside of the can. The threads towad the outside of the can have to seal to not leak)



So, I use the tank filler line to drain the bed into the OEM tank and the DS II to vent the OEM tank back to the bed tank (which is also vented to the outside through a lawn mower fuel filter to keep bugs out on a different fitting)



Just my experiences with bed tank to OEM filling and venting,



Bob Weis