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Funny thing, on my truck, I have both the manual valve and the electric valve. Both have pieces of old hose on them so they were used at one time. The electric valve is mounted to the floor of the cab and looks factory installed because of how the wiring looks. The wire gets hot when I flip the dash switch. Maybe supercabs were different.
On my father in law's truck, now mine (78 F250), the dash mounted switch controlled both the fuel flow and gauge. That said, the auxiliary tank was rusty and dirty. We bypassed the switch and ran on the rear tank. That reduced filter plugging/changing. Later the auxiliary tank was removed. Then we replaced the rear tank and rubber lines. Fuel problems were fixed. I now wish we had put the 38 gallon in the rear... that's a winter project. I don't miss the mid mounted tank at all.
D5TZ9A050A .. Fuel Tank Switch / Mounts into the heater control panel, on the opposite side of the blower switch.
D5TZ9189B .. Fuel Tank Selector Valve and Solenoid Assy / Mounts on the left (drivers) side frame rail.
Helo, I have a 1978 F-250 with duel factory tanks. I am not able to make the solenoid switch change fuel lines. The switch works but I am not getting power to the solenoid. I am at the point where I am checking the dash selector switch for continuity. I am not sure which pins on the switch to connect with my ohm meter to determine continuity in the switch.
On the switch there are two orange wires. One comes from the fuel gauge, the other is 12V power to the tank valve solenoid. That's the one you want to check, the ones that opposite the brown/white wire. The brown/white wire goes from the switch to the solenoid.
On the switch there are two orange wires. One comes from the fuel gauge, the other is 12V power to the tank valve solenoid. That's the one you want to check, the ones that opposite the brown/white wire. The brown/white wire goes from the switch to the solenoid.
So to check continuity of the switch, I check between the two pins on the left with the switch in aux position? If so, there is continuity between the two pins on the left in the pic. I checked the continuity of the brown/white wire and I get a low reading. Possibly a short along the frame somewhere?
The plug you show in the picture and the wiring diagram don't match. To your knowledge, has there been any rewiring done in the past?
What I would do is first, make sure which wires are which.
Where the schematic shows two orange wires, you have one brown w/ white trace and one red. Use a voltmeter and with the ignition "on" check for voltage. If these are in the correct location, one should show 12 volts, that's the one for the fuel solenoid, and one should show ~5.5 volts, that's the one for the fuel gauge.
For the other three wires, one should go to the fuel tank solenoid. I would get up underneath the truck to verify which wire is going to the valve. You don't want to send 12 volts to the tank sending unit.
There has not been rewiring done in the past; I am the original owner.
I followed the brown with gray trace wire along the frame from the selector switch to the connection at the firewall and is was good. This connection was not so good so i shined it up and put some dielectric grease on it and it now has a good current flow.
From post #21 above: When the switch is in aux position the brown with gray trace and the red wires power the solenoid tank selector switch along with the blue with gray trace and orange wire which power the sending unit on the mid ship tank and fuel gauge. When the switch is in main position, only the orange wire and green wire at the rear tank are connected which power the gauge.
I have read discussions on this site about which tank is the main tank and which is the auxiliary tank. According to the wiring, the rear tank is the main tank and the mid ship is the auxiliary tank. However my rear tank has the fuel going through the auxiliary port on the selector switch, HA. I have always noticed that the mid ship tank was the main tank according to the gauge.
Nice, original looking truck. Don't want to sell the camper shell do you? J/k, mostly. I'm going to go home now and fool around with my selector switch and check continuity.
Nice, original looking truck. Don't want to sell the camper shell do you? J/k, mostly. I'm going to go home now and fool around with my selector switch and check continuity.
I really fixed a lot of parts before arriving at checking the connection of the selector switch wire at the firewall. I have new filler hoses on both tanks and filter socks on the fuel tank pickups. The mid ship tank carrier had some rust holes. I ground down the rust with an angle grinder brush, first removed the carrier angle iron holder and riveted it back on, first coated the metal with phosphoric acid then repainted. It took a long time to determine why the truck would just quit running. lol. A problem is usually something simple they say, also hind site is 20 20.
This shows .75 inlet (online tech info) but is it NOT for 3/4" line....After an actual hands on test fit, 5/16 does fit on it, but it is super tight, like is it NOT for a 5/16 line for sure. But you can make it work if you have to. And a 3/8 line does fit and it is not sloppy, like it is to big or not the correct size line. Hose clamp and go.
09-03-2013, 04:34 PM
jen
