Auxiliary fuel tanks

[4x4hunter]

Have 120 gallon auxiliary fuel tanks on several of our Duramax diesel rigs.

Having a fuel feed problem on one of our 2004 C4500 Kodiaks. Dealer in Colorado disconnected the aux. tank claiming the 3/8" feed lines are too small and all plumbing has to be 1/2". Now we're on the 25 gallon stock tank, which means we have to hit every other gas station. Personally, I think dealer is full of BS as don't have any problems with our other similarly equipped rigs.

Haven't had a chance to run it only on the 25 gallon tank and see if cured our problem as had a tow truck yank our truck from that dealership and take to another. Friggin' idiots wanted to argue with my driver that he should have used his engine block heater overnight as engine started then died and w/n start again, the morning after they "worked" on it. This truck has NO engine block heater setup. It's a Texas truck.

When new dealer received it, they ascertained that the first dealership had run the 25 gallon tank dry and hadn't switched the fuel tank selector switch from our, now disconnected, aux. tank, so the guage was reading full.

I checked with several 4X4 and custom type shops who agree with me. They use 3/8" with no customer complaints. One advised they equipped 4 Kodiaks a few weeks ago - all with 3/8" and numerous 3500's over the years and no problems.

Anybody experienced any similar problems? Are 3/8" feed lines adequate or inadequate?

[dmaxalliTech]

3/8" line should be adequate. Its job is to simply transfer fuel to another tank, not supply the engine. It does not have to be a fast process. The chassis cab trucks use 3/8 line OEM so it will be fine for an aftermarket tank

[4x4hunter]

Thanks, DmaxallTech for confirming my thinking!

[rickdlance]

You might be lucky. My dealer told me that altering or adding to the fuel lines in any way, shape or form would void warranty. I use a transfer pump to pump from my auxilary tank to a ftting in the filler neck of the stock tank. Dealer said this was the only way I could do it and not void warranty.

[justforme]

Originally posted by rickdlance:
You might be lucky. My dealer told me that altering or adding to the fuel lines in any way, shape or form would void warranty. I use a transfer pump to pump from my auxilary tank to a ftting in the filler neck of the stock tank. Dealer said this was the only way I could do it and not void warranty. iv'e been doing the same thing since 01.

iv'e got two 3/8 lines going to my filler neck.
one is a return so i cant over pressurize the primary tank.

[crew84]

I know that there is a law that can challenge the dealer. I have put money in an account to use against GM if they try to void my warranty because I put an extra fuel filter inline. I feel with their track record on fuel contamination excuses to void warranties will bite them back. This forum has many examples that can be used. They would have to prove it caused the failure. I will have experts to their experts.