Aux Fuel Tank installation

[hdrk60]

Just bought a RDS aluminum 60 gal, combo tool box and aux tank for 2nd gen 3500 RAM.

Trying to decide whether to connent to filler hose and gravity feed as described by RDS or to connect using pump and filter/water seperator before it enters main fuel tank.

Has anyone installed one? Any problems or advantages either way?

Thanks for your comments

 

[steved]

Being a 2nd gen, you ought to be able to gravity into an unused fitting on top of the tank...

I have a 3rd gen and spare tank, I have a pump and don't really need it... it gravity feeds through a water separator, pump, and 10 micron filter just fine. The only time I use the pump is when I'm filling up... I use it to pump the fuel into the filler neck so I know it has the same amount of fuel as before.

If I was to do it again, I would forgo the pump... and just gravity feed from the tank, through a filter, and into the main tank. Just remember to place a small shutoff valve near the spare tank.

steved

 

[steved]

http://www.tdr1.com/forums/showthread.php?t=172769&highlight=tank



Here is my installation...



steved

 

[Joe G.]

I found an odd problem with gravity feed. I had a anti-siphon valve on mine and removed it because it was interferring with my aux tank fuel lever gauge readings. At that time I also had an electric pump. It played out and I replaced it. This pump allowed gravity feed through it. The old one did not. I filled up both fuel tanks when the price of diesel was a little bit lower than usual. I drove from town home and parked in my garage. The next morning I noticed a little spot of fuel on my garage floor. It was about 2". I suspected that the fuel module gasket was leaking. However, I had some fuel on the top of the module which a gasket leak won't do. I saw a little drip on the pressure relief valve. I put a hose on it so the drip would be in a cup if that was really the leak. It was. There was about a table spoon of fuel in the cup the next morning. Gravity feed from the aux tank in the bed was enough pressure to cause the pressure relief valve to leak a little bit. I had not noticed the leak before because it is so slight that wind blowing over the tank would take care of it. At a lower fuel level in the main tank it would not fill enough over night to make the pressure relief valve leak. I have changed the way my aux tank works now.

 

[RJOL]

Put a 35 gallon tank in the bed of my 2001. I ran the hose through the inside wall of the box and put a ball valve on it and feed it into the vent line with a tee. I did not add any pumps/filters or whatever. This worked like a charm except for the following.



I could not just open the ball valve and feed the aux tank all the time. I had to run the OEM tank down to less then half, then open the ball valve, and loosen the fuel cap on the OEM tank and the aux tank. I used to do this when I was stopping at a rest stop, or where ever, and it really doesn't take that much time to transfer the fuel. Once the aux tank was down to less then half a tank. it would feed the rest of the fuel into the main tank by just driving and leaving the ball valve open.



One other thing... If you do it this way, don't forget to close the ball valve before you fill up both tanks. If you fill the main tank, then try to fill the aux tank with the valve open, you will get a nasty surprise out of the main tank fill. Only made that mistake once...



This setup worked fine for years, and it still is working today (sold my 2001 to a friend). He has had no problems with it...

 

[steved]

I could not just open the ball valve and feed the aux tank all the time. I had to run the OEM tank down to less then half, then open the ball valve, and loosen the fuel cap on the OEM tank and the aux tank. I used to do this when I was stopping at a rest stop, or where ever, and it really doesn't take that much time to transfer the fuel. Once the aux tank was down to less then half a tank. it would feed the rest of the fuel into the main tank by just driving and leaving the ball valve open.

That's odd, I have mine plumbed into the main tank with a ball valve and I can leave mine on all the time... no overfill, no issues with it not gravity feeding.



And mine isn't a bottom feed, it's a top feed fuel cell... its first got to lift over the top of the cell, then gravity/siphon into the main tank.



steved

 

[RJOL]

That's odd, I have mine plumbed into the main tank with a ball valve and I can leave mine on all the time... no overfill, no issues with it not gravity feeding.



And mine isn't a bottom feed, it's a top feed fuel cell... its first got to lift over the top of the cell, then gravity/siphon into the main tank.



steved

Don't know what to tell you. Mine feed from the bottom of my aux tank. Both the OEM and the Aux tank had OEM gas caps on them that allow for air into the tank, but not out. I tried to feed it by just opening the ball valve but it either was very very slow (i. e. after driving for miles the fuel gauge didn't seem to be coming up). Also, you didn't have overfill problems cause you feed through the top of your tank. Your system must create some kind of initial vacuum to get the fuel over the top of your tank and then gravity feed into the main. Are you going through your vent pipe or directly into your tank?

 

[steved]

Don't know what to tell you. Mine feed from the bottom of my aux tank. Both the OEM and the Aux tank had OEM gas caps on them that allow for air into the tank, but not out. I tried to feed it by just opening the ball valve but it either was very very slow (i. e. after driving for miles the fuel gauge didn't seem to be coming up). Also, you didn't have overfill problems cause you feed through the top of your tank. Your system must create some kind of initial vacuum to get the fuel over the top of your tank and then gravity feed into the main. Are you going through your vent pipe or directly into your tank?

I have the cell plumbed into a homemade water separator, then the pump, then a 10 micron filter, and finally into the fill line for the main tank (actually tapped the return for my FASS).



I have the cell vented to both the main tank (via a separate vent line hooked to the main tank's vent line) and to atmosphere (vaccuum only, it will build pressure). I did this to prevent potentially overpressuring the main tank with the pump (didn't know what the main tank would do with 14psi of dead headed pressure).



Once I start down the road (with the valve open), as long as the lines are filled (over a gallon of "void"), it will fill the main tank quite fast without even starting the pump. If I start with a half tank in the main tank, it will fill it to over 3/4 of a tank in less than 50 miles (gains that fast). If I leave the valve open on a full tank of fuel, the guage won't budge off full for over 400 miles.



And this is with 3/8" hose.



I don't follow you on "filling from the top of the tank"??



steved

 

[Joe G.]

After I discovered that gravity feed (siphon in my case) could cause a leak from the pressure relief valve I changed the system completely. I rigged a tank select valve near the engine in the supply hose to the fuel heater. It normally uses fuel from the main tank. If I activate the select valve it uses fuel from the aux tank. Fuel return is always to the main tank. So the stock lift pump is doing the pumping. I turned it on with the main tank fuel gauge at just a little bit over 1/4. 15 miles later the main tank was full. The stock lift pump will really move fuel! The line from the aux tank to the selector valve is 3/8".

 

[RJOL]

I have the cell plumbed into a homemade water separator, then the pump, then a 10 micron filter, and finally into the fill line for the main tank (actually tapped the return for my FASS).



I have the cell vented to both the main tank (via a separate vent line hooked to the main tank's vent line) and to atmosphere (vaccuum only, it will build pressure). I did this to prevent potentially overpressuring the main tank with the pump (didn't know what the main tank would do with 14psi of dead headed pressure).



Once I start down the road (with the valve open), as long as the lines are filled (over a gallon of "void"), it will fill the main tank quite fast without even starting the pump. If I start with a half tank in the main tank, it will fill it to over 3/4 of a tank in less than 50 miles (gains that fast). If I leave the valve open on a full tank of fuel, the guage won't budge off full for over 400 miles.



And this is with 3/8" hose.



I don't follow you on "filling from the top of the tank"??



steved

Well your system is a little more complicated then the one I used. "Filling from the top" means you said you don't feed from the bottom of your aux tank...

 

[steved]

Well your system is a little more complicated then the one I used. "Filling from the top" means you said you don't feed from the bottom of your aux tank...

Yeah, I have a pickup tube like a "normal" tank.



So far, I have been able to turn the valve on and leave it sit for days... no leaks. It will fill the main tank to the point that it will take another 3 gallons (via pumping) to fill it into the neck (how I know when its "full" consistantly for gauging mpg).



steved

 

[JVantreese]

I am using a gravity feed to an adaptor that has been added to the filler hose. It is available from Northern Tool and has a check valve to prevent overfilling the OEM tank. I have a lockable OEM fuel door (Geno's) and leave the door locked. I fuel my truck via the aux tank. My capper has side windows (lockable and wired into my alarm system) that open and the aux tank has its fill on the driver side level with the bed rail. When I need fuel I open the side window and fill the tank. I do not filter the fuel from the aux tank as all fuel is consumed from the OEM tank and therefore is filtered by the stock system. My 80 gal aux tank feeds from the bottom and has a shut off at that location so I can turn it off if I choose to. The aux tank is also vented. There is a rollover valve at the vent and I added about a foot of fuel line so that the vent is well elevated above the top of the tank. When I leave the aux tank on it keeps the OEM tank full until the aux tank is empty. If I see my OEM fuel gauge drop below full, I know that the aux tank is either turned off or empty. I reset my trip odometer when I fill the aux tank and know that I have about 1500 miles range before I need to look for fuel. I do use a mixture of Power Stroke and MMO as an additive and an algicide treatment about every six months. This system is simple, inexpensive, and it works just fine. It is nice to be able to pick and choose when and where I fuel up.

 

[dezeldog]

I have the same system as JVantreese except I have a racor 2 mic FF/WS between the aux and the OEM tank along with a shut off valve. It has worked flawlessly for over 40k mi.



Jim