deviousracing

I just bought a fuel/toolbox combo tank from northerntool.com and am kinda confused after reading some posts on installing it. I wanted to do it gravity feed because its cheap. In some of the posts I read it says that it can over fill the stock tank without a shut off valve. Im confused as to why it will overfill and leak out, is there a hole on the top of the stock tank or something? if so how come dirt and crap dosent get in the stock tank or is it a one way valve of something?

infidel

The stock tank is vented on top of the tank and though the fuel cap to prevent vacuum and pressure. They are set at something like 2 psi of pressure and vaccuum.
If it's filled to the brim it can only vent fuel. Way to prevent this without a valve is to add a new vent by relocating the small vent hose next to your stock fill hose so the top of it is above the level of fuel in the aux tank. You will either have to plug or use the high attachment for the stock vent hose as the feed for your aux tank.

Festus

I rigged mine up this way: aux. tank to inline fuel filter, to electric valve (Napa), T'd into vent line on filler. Whenever tank gets full according to my guage, I just turn the switch off - otherwise it will overflow - learned that from experience too.

Hemi Cat

Most DOT's don't like gravity feed fuel lines. I would recommend plumbing up a motorized fuel change over valve and run two lines to the top of the aux tank. You could also put a universal fuel sender in and wire it up to the change over valve so your guage works.

deviousracing

Can I go to a local auto parts store and get a fuel pump, does it have to be for diesel only? i have a checker and pep boys by my house thanks for the info

Gear Poet

I've got a 25 gallon metal & poly circle track tank in the bed, plumbed into the main tank by way of the extra feeder line on top. I use a cheap electric fuel pump from Advance Auto and a fuel filter to transfer fuel. That pump and set-up has lasted for 3 years, no problems. The whole thing cost me $224 and change.

Lightman

This is totally not necessary. The stock cap is sealed and will not vent out fuel. Neither will the top of the tank vents. I have the RDS (same as they sell at northern tool) box hooked up on my truck via gravity feed and have no such issues when leaving the valve open for weeks at a time with both tanks full.

Devious what you need to do is get a ball valve and install it in the drain at the bottom of the tank. Then run a hose from there down thru the bed and T into the 3/4"ID filler neck overflow tube and you will be good to go. I installed a racor 2 micron fuel filter/water separator in between, and the weight/force of the gravity is PLENTY to push the fuel right thru the filter and into the main tanks. I love that it's filtered before it hits my tank. There is a vent on the aux tank right near the fuel filler cap, which lets air displace the fuel that leaves the aux tank. I have run a hose from this down thru the bed and attached a 2 micron foam breather filter to the end of it, tucked way up underneath the body, near the inside of the filler neck. This way all the air that's sucked in is clean and has less chance for moisture to enter the fuel. Yes this is probably overkill but the thing was only $15 bux and I spent a total of $500 to buy the tank and all of the fittings... Pretty cheap compared to the transferflow setups that START around $1000 for a tool/tank combo - and thats not including all of the fancy electronics. You will have to decide how you feel about DOT. I'm fine with it and don' t ever see having an issue with my gravity feed. If you haul commercially and get inspections, you might want to think a little harder about it.

If you search for a post by FiverBob - I believe he may have listed a breakdown of all the parts he used in a similar installation. Thanks to meeting up with Fiverbob in person and seeing his setup, I gained the confidence to buy and install the tank myself in this manner. It's sweet having 87 gals capacity till it comes time to fill. So far my record is $180 and I never let it get that low...

electrifried

I used a 6 port motorized valve from whitney for about 85 bucks and it switches the gage in the process. Sure seems like an easy way to meet all codes. No way to spill etc.......


As an afterthought, when changing a lift pump that was a bit old before a long set of runs, The fuel literaly poured out. having that head of pressure has to help something

kelley15

I have an aux .tank under my toolbox. It is about 35 gallons. When I get to a quarter of a tank. I open a half inch tubing valve and let gravity do the rest. It wont overflow.

wmatt

There must be a difference between 2nd gen and 3rd gen fuel tanks. As Festus mentioned his would overflow and mine definately overflows, but no one with a 3rd gen seems to have that problem. Just thinking outloud.

Maccandy

There must be a difference in fuel tanks. My tank has 2 small vents, one on each end. I put a 1/4 in. hose on them and was able to suck and blow air through both of them. So if they are open and you have fuel coming in from an extra fuel tank it would seem to me that I would have diesel all over the place. Am I missing something?

Lightman

Maccandy - we have the same tanks with the two little vents that people all freaked out about(water intrustion) and ran out and put hose extensions on ...(myself included ) Anyway I can tell you for a fact that fuel does NOT leak out of these, whether you can blow thru one or not. I sometimes forget and leave my ball valve open on the aux tank for weeks.. and the fuel gauge in the truck stays pegged way past full for about 75miles till it moves, very similiar to if you take the time to fill ALL the way up or have that vent kit. I'm not sure why, but I can tell you that it does not leak out anywhere. Several other members are also running them this way with zero problems. Maybe Fiverbob will chime in , as he has the same setup as well.

justcampin

I have mine like Lightman as for the D.O.T. issues all semis gravity from one side tank to the other to keep them equal, they have a crossover line on the bottom of the tanks to equalize them, the rule is " A fuel system must not supply fuel by gravity or syphon feed directly to the carburetor or injector" if you want to read the DOT rules..
http://www.fmcsa.dot.gov/rules-regul...csr/393.65.htm

Lightman

Justcampin thanks much for clarifying that. So many guys on these forums have told me that my setup is illegal when trying to justify the added cost of their transferflow electronic gizmos or electric fuel transfer pumps. It looks like most read the 'gravity or syphon prohibited' statement and didn't read further.

TxDiesel007

Devious

PM in ur mailbox... write back asap... thanks

Disregard that... I had my dad explain to me how to do this, so i thought id share it with anyone else trying to install a gravity feed tank..

There are two lines, one that is small, and one which is a return line, and the other one feeds fuel to the engine. You have to cut the return line and plug it very securely going to the tank, the other end of this line, (goin to the engine) needs to go connected to the auxilary tank (high) this will be the excess fuel returning from the engine. I remove the steer filler section from the hose clamp and then use one and half inch OD tubing with a secotion of about 16 inches of one and a half inch ID rubber hose. Up to the auxilary tanki with a one and a half inch fitting into the tank. That way when you fill up the ausilary tank, the main tank gets dilled up very quickly and your fuel gauge will always be past full. When you gauge starts to drop, it means that you auxilary tank is emplty and you are running on your main tank..

That is what i understood.. Hope this helps. now the reason that it leaks is because of the gas cap.

Hope this helps..

Tx