I added a reserve fuel supply to my 77 cherokee by installing a tank in line between the
fuel filter and the main fuel tank. The installation required a small tank (I used a 3 gallon tank), replacement
of the rubber hose that connects the fuel return line to the main tank, the addition of a fuel tank selector switch,
and fabrication of some steel lines to connect the new tank.
The installation did not require cutting of any body panels for a filler neck, cutting of the
main tank filler hose, or installation of a separate vent line. I installed the tank without a sending unit, so
there was no gauge to install or wire.
The reserve tank is filled by fuel running through the return line to the main tank. It takes about
10 minutes with the engine running to transfer enough fuel to fill the reserve tank. When the reserve tank
is full, the overflow continues flowing and goes to the main tank, just as it does in the stock setup. Venting of the reserve
tank is through the overflow line to the main tank, and fuel in the reserve tank is constantly being refreshed,
even if you do not use the reserve fuel supply.
Access to the reserve fuel supply is through a fuel selector valve (electric or manual - I used an electric
valve for more flexibility in locating the valve). If you need more fuel because the main tank is empty, flip
a switch and you have another 30-40 miles of driving range.
My cherokee has the optional dealer installed spare tire carrier inside the cargo area, so I used some of the
space under the cargo floor for locating the reserve fuel tank. The tank can be installed where ever there is
room under the vehicle.
The component costs:
3-gallon stainless steel air compressor tank - $60 (purchased from Ebay)
12-volt electric fuel tank selector switch - $50 (purchased from Ebay)
5/16 and 1/4 inch rubber fuel hose - $6
1/4 and 5/16 npt fuel hose fittings - $15
a bag full of small hose clamps - $5
3 pieces of steel fuel line - $0 (salvaged from a parts vehicle)
12 inches of 1/4 inch copper tubing - $0 (leftover from a past project)
I can provide more details if anyone has an interest.