Question: Anyone know why the reserve gas tank on a 1993 Ford F150 wont work ?  The  electric switch on the dash seems to work, as the gas gauge moves when I  switch it over.. BUT, the engine cuts out like it isnt getting fuel. And  yes.. there is fuel in the second tank

Thanks !

Answer: I’m not positive, but I believe that there are electric pumps inside the  fuel tanks. Assuming that’s true I would have to guess that your second  tanks pump is either dead or clogged.  Rob could be right, but I once had a hose simply come off the in tank pump.  Put it back on with a hose clamp, worked fine. Either way you’ll have to  drop the tank to find out.  My 92 had a recall for a problem of fuel returning to the wrong tank, the  fix was to disconnect the fuel supply line from the outlet on the top on the  tank and install a check valve,  then reconnect the fuel line to the output  of the check valve.

I found the the failure mode of these valves is to restrict fuel being  delivered by the pump. making it appear as though the pump has failed. Ie.  engine cuts  out or runs like its starved for fuel, (cuts out- surges) .  You may want to check that out before replacing the pump. (If you hear the  pump running) If you don’t. check the ground for the pump(s) located around  the center of the underside of the bed on the frame, Each pump (one in each  tank) have separate grounds..  Since one tank is ok, It’s the switch (not  likely), checkvalve, ground, then suspect the pump.

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