1970 Jeep Dj5 (fuel System)

edit:: was directed to move this to this thread::

I was trying to make heads or tails of the fuel system in a 1970 DJ5. It would seem that the system originally included a vapor separator, and has a total of 3 lines running back to the tank. I would like to omit this, and bring it down to bare bones to have less parts to fail.

The tank has 2 inlets that were used from the vapor sep, so I am assuming I can just loop a hose from inlet to inlet and be done with that. There is the actual filler neck which is self explanatory enough I would think. There is the fuel sending unit which only has a single wire, so I assume that would be positive, and I would ground to chassis. The sending unit also has a line out, which is what I will run to the mechanical fuel pump with a standard in-line fuel filter. lastly, there is what looks like a one way "breather" check valve next to the filler neck, so I planned on running a small line to direct any overflow away from metal / body.

Using this concept I would only need a single fuel line from tank to engine bay, or will I require a return line? Or, should i just inject a T fitting after the mechanical fuel pump, before the carb and run a line back for excess pressure to avoid vapor lock? Thoughts?

Under the hood I have the line running to the mechanical fuel pump with an in-line fuel filter. which will run to the little 1 barrel carb, sitting on the AMC 232 inline 6. I do not see any return lines, so that is why i assumed i could use a single line to the tank.

Lastly, I recall some older system used a charcoal system in conjunction with the vapor separator, but not only do i not see it, nor do i see where an outlet / return line would come from.

Any insight / photos / guidance would be greatly appreciated!

Rob

 

The sending unit is not powered it is a wire from the gauges. As for a return line there is a filter with the return built in the line goes from the filter to the tank. Looping the two vents works but you will need some sort of vent to prevent pressure build up.

 

Great to see another DJ owner here!

The separator you're speaking about - the one in the left rear quarter panel? That's a passive condenser. It takes two inputs from the top of the fuel tank and is supposed to collect the vapors and route them to the front into a charcoal can. When I redid mine, I just left it. The fuel tank had the plumbing, so all I had to do was replace the two rubber tubes from them to the can, and then re-run the line from the can to the charcoal up front (I replaced all of the fuel lines). If I decide to ever give up on that, I can always recycle the line to be a fuel return line.

Depending upon who you talk to, you'll get different answers about the fuel return line. I have a 1975 engine (the 232), and the carburetor has a single fuel line connector. The ancient fuel filter was single in / single out, as well. Seeing this, I just stuck with a one way fuel line. Doesn't seem to make a huge difference to me. Others say to get a more modern fuel filter with a return line to avoid over-pressure. If it wasn't there originally, then why ask for trouble by adding it now, eh?

j