Aux fuel question

[moparguy]

So, I've picked up a marine tank for the truck. It fits fine in the front of the bed with only two issues. The fuel inlet and outlet.



The inlet I can handle and the outlet I think will work, just need a second opinoin or two. The outlet has a fuel pickup tube mounted on top of the tank extending to within about a 1/4" of the bottom.



If I tie the aux tank into the filler neck and block the factory tank vent, venting both tanks throught the aux tank will it siphon down into the factory tank as long as the oem fuel cap is tight?



I don't have the ability to weld aluminum or I'd put the outlet along the bottom of the tank and just gravtiy feed and forget the siphoning bit.



Thanks,



RJR

 

[Joe G.]

I tried several options. I tried electric fuel pumps but they were unreliable and too slow. The siphon feed worked but it overpowered the pressure relief valve on the fuel tank module and caused a very slow leak. I ended up buying a tank select valve and mounting it on the frame rail just in front of the firewall on the driver's side. I rigged some fuel hose from the stock steel line that goes to the lift pump to the normally open valve of the tank selector valve. The output from the tank selector valve goes to the lift pump. Then I ran a line from the aux tank to the other input to the tank selector valve. The return line goes back to the main tank. I have a fuel level gauge for the aux tank. One thing I found out is that the stock lift pump will move fuel at about 30 GPH so you have to pay attention and not run the main tank over. The other thing to watch is how low the aux tank is. I have run out of fuel a couple of times by not keeping an eye on that. No problem restarting, but it can be a nuisance.

 

[moparguy]

Thanks Joe, I would never have considered the likelyhood of a leak you decribed on the fuel tank module.



RJR

 

[steved]

I have a racing fuel cell similar to your marine tank (and FYI, I considered a marine tank). I used a 140gph fuel pump from summit racing (similar to a holley blue).

The tank WILL siphon once you get it started with the pump (and continue with the pump turned off)... and siphoning will keep up and exceed the demands of the engine under normal loads. Again, I only use the pump to start the siphon... I also use the pump to "top off" when I a fueling (keep the fuel cap open and watch for fuel in the neck). I do use 3/8" hose and fittings...

I've had mine for well over 25k without a single issue (other than the single time I accidentally turned the pump on). I would not hesitate to use a marine tank and electric pump.

steved

 

[viper700]

I mounted a tank 65gal that my son made for me in the back of my 04 dually. There might be a legal issue of having a siphoning situation in transfering fuel with the possibilty of dumping your fuel on the ground. I first used a Holly pump and that proved to be a big pain in the tail as it would not pump when temps were below freezing. I then went to a Carter # P4601HP this proved to pump diesel way down on the cold scale. I used a pollock fuel tank switch and pluged up half the ports so it would shut off the fuel flow and not to continue to siphon fuel. The marine tank with a top pickup is the way to go. I made an Aluminum box that mounts under the p/u bed next to the filler neck that holds the pump and switch. I tied the transfer tank vent to the main fuel tank vent line so it is a closed system. I put a marine fuel sending unit in the tank with a guage in the cab with a switch with a light to remind you it is on when transfering. These transfer tanks have been discussed many times, do a search and you will many ideas and examples.