Fuel return line, MCI 9

[grantgoold]

I am trying to design a system that allows me to pump extra diesel fuel into the main tank as required during travel. I know the main tank has a fuel return line. I was hoping to tap into this line at the tank to provide a second method of auto filling the tank from a second tank on board. I am concerned that when I send fuel from the second tank to the primary, fuel will actually run into the return line and cause issues verse down the tank.

Any ideas on how to prevent this while underway?  I do not want to cause problems with OEM set up.

Thanks

Grant

[tekebird]

curious why you need more range than the stock tank allows. there aqre few people who can outlast a full tank of fuel with their driving stamina

[Brian Diehl]

Hey Grant,
The return line has a one way check valve at the rear engine bulkhead.  So, pumping into your tank at the return line connection on the tank will not push fuel back up the line if the check valve is in good condition.  Secondly, board knowledge has it that the engine will be pumping gallons of diesel thru that line every hour.  So, you should have some small amount of positive pressure at the return line due to the engine fuel pump.  I would imagine your idea for connecting to the main tank will work just fine as long as you don't try to over pump the fuel thru.  

[gumpy]

Since your aux tank will probably need to reside in one of the bays, I would think it would be easiest to simply run a copper line through the bulkheads, across the battery compartment, and tie it directly into the main tank. If you have you floor up, you can get in easily behind the battery compartment. Might be able to snake a line in that way with the floor in place, if you pull the fresh air cable pull out of the forward  bulkhead. I think would be much easier than trying to tie into the return line, but if for some reason you need to do so, you shouldn't have any problem using the return line.

craig

[TomC]

I would suggest (as stated on your other post) that you get a 12v fuel transfer pump with gas station type nozzle that you could fill your self up from the aux tank if needed.  Then you're not touching any of the OEM factory fittings.

Personally don't know why you want to do this, or even run the aux tank, which is a waste of space.  You most likely have at least a 130 gal fuel tank, which at 90% useage at 6 mpg will get 700 miles of driving.  I know I like to stop every hour or two if nothing else to check the tires (especially in hot weather).  When I'm going to be at a dry camp (no hook ups), and relying on my gen, I just fill up at the closest to camp fuel station.  Even when dry camping for 5 days (the longest I've done), I'll accumulate maybe as much as 20 hours of gen time, which is about 10 gal of fuel.  Unless you're going to be living in the wilds for weeks on end, the extra fuel tank is just not necessary.  You can tap into the main tank for Diesel, of course if your gen is gasoline, then you'll need the aux tank.  Good Luck, TomC