Fuel tank overflow - Diesel Forum

mjb59 · 07-02-2008, 11:15 PM

'02' F250 super cab SWB I have tried to fill the tank as full as I could get it on normal fillups. I now have an extra tank in bed that has a gravity feed to main tank. I have always kept the pit**** closed (until needed) until now. Friends who have Chevys always left theirs open. On last trip I opened it while stopping to eat. Came out and there was a puddle of diesel on the ground. It looked to overflow at the connection of electrical and feed for motor on top of tank.(Large round screw cap) Is this not like the Chevys? Does it have a breather on top of the tank? I need help.

klhansen · 07-04-2008, 03:42 AM

Might be the fuel line quick connects on the top of the tank. They're o-ring sealed and are notorious for leaking under vacuum (pump suction). Maybe yours has gotten bad enough that it's leaking under the pressure from your aux tank. If that's the case, the fix is to cut off the QD fittings and replace with hose clamps.

jordanmills · 07-04-2008, 12:03 PM

There's also some other QD for air flow under there. Those might have also come undone.

Kanman · 07-05-2008, 02:08 AM

I believe there are two breathers on top of the tank; one on each end of the tank. About every other tank I have dropped has a broken vent line on the rear breather. If your meats are small enough you can probably fish around on top of the tank to verify.

Probably wont help your situation, but Northern Tool sells a kit that controls overfilling. Diesel Install Kit for Auxiliary Diesel Fuel Tank — Fits Ford and Dodge Trucks, Model# 011025 | Auxiliary Fuel Tanks | Northern Tool + Equipment I purchased one, but never installed it; so I cant really say how well it works either way.

taxgod4u · 07-06-2008, 12:10 AM

I have that kit installed. I would not call it an overflow preventer as the ball in the valver does not look like it will "float" up and stop the gravity feed. I would liken it to a roll over valve to stop the flow should you flip the rig.

smittymcbay · 08-18-2008, 03:24 PM

I had a tank that was a gravity flow for about a year. It was nothing but problems. The factory tank was alway leaking from the top of the tank after installing the transfer tank. Once my wife opened the filler cap on the factory tank to fill it up. The diesel clean up cost us $3500. The last straw was when a trooper saw the RDS tank and the hose connected to the bottom of the tank. They towed my rig to impound. They made me remove the tank from the truck and the premises. Then I got my truck back.

I asked them why. I thought the regulations said no gravity flow to the carb. I was flowing to the tank. They said that's true. They said the DOT regulations state that the fuel pick up point has to be above the highest fuel level for a fuel tank. It was another expensive lesson to learn.

I decided the $600 tank that I saved so much money on was costing me an extra $8,000. I sold it on EBay for $100. I have a system from American Tank now, www.auxtank.com. It cost me $1500, but I have had it on 4 trucks now and have almost 1,000,000 miles on the system. All we did was replace the fuel hoses each time. When I put it on my 2008 Ford, it cost an extra $150 for a sending unit. I have been pretty happy with it and will never buy from anyone else.

I think you should get away from the gravity flow setup. My buddy runs a TransferFlow, Aftermarket and OEM Fuel Tank Systems, and has been very happy with it. It was also about $1800, but is worth the extra money in the long run.