Hey everyone, I need some help with wiring. I have a 1981 F250 Ranger Lariat Trailer Special, 2wd, 400 motor, automatic c6. I bought this thing mint barn find. Only issue is it was a dealer option propane truck. Ran great, but I always wanted to put back on fuel. So I did. Bought all the tanks etc, and a Fitech fuel injection system. All went great until I went to wire the fuel tank selector switch. I have the Fitech fuel system too, so it came with a selector valve. Thats not the issue. The issue is the wiring can be done with there switch, or the factory switch, which fitech shows as a 4 wire. Thats an issue, because my stock switch is 5 wire. Hmmm? Theres is a 6 wire, but they provide a different wiring diagram for the stock switch, except for 4 wire. Now the big issue. I figured I would just trace my wires, test and probe, figure them out. Also have a haynes manual, but it has no fuel tank switch wiring diagram, only shows a fuse for the aux tank. So I cant find a diagram to match my switch, 5 wire, and the ones I do find have totally different wire colors, so tracing is impossible. I did test the switch pattern and will post because it confused me more. Lol. I need a wire diagram for my truck and wire colors so I can tap the correct wires to hook to the pump and valve. Single pump by the way. Now the switch. Its on the heater control assembly and is stock. Here is what the test light does in each switch position on each wire.

.................................................. .........................Front Tank.............................................. ......Rear Tank
Red............................................... ......................... Hot .................................................. .............Hot
Black White .................................................. ..........Hot .................................................. ..........nothing
Brown Yellow............................................ ........... Flashes .................................................. ......nothing
Yellow White .................................................. ......Flashes .................................................. ......Flashes
Yellow Green or blue dashes............................... nothing .................................................. .......Flashes

So I assume the Red is fuse power to the switch
Black must be the tank selector valve power, hot front tank, cold rear tank
No ground, which the fitech valve asks for off the switch
I assume the flashing ones are for the gas tanks fuel gauge, one pattern front other rear??? If so, which wire goes to which tank fuel sender? Fuel senders have 2 terminal.??

Here is what the fitech wiring asks for
It has a straight line plug labeled A,B,C,D,E,F F is blank not used

For the 4 terminal switch they want,

Top right terminal goes to E, which goes to E on the valve, and then to front pump
Top left terminal goes to D, which goes to D on the valve, and then to rear pump
Bottom left terminal is grounded
Bottom right terminal goes to 12 volt supply, key on

So thats the wires off the dash switch
Once at the valve, D and E are used of course to the pumps. MY ISSUE IS I HAVE ONE PUMP, SO WHICH WIRE DO I USE TO MY PUMP????
C goes to the rear tank sending unit, which is what? the fuel gauge? And again, which terminal on the fuel tank sender, and do I just ground the other??
B goes to the fuel gauge, so I assume it operates for both tanks depending on the switch position, front / rear?
A goes to the front tank sending unit, so if C is the rear tank sender then B reads off of A or C depending were the switch is, front/ rear?

So hope thats not confusing. The valve is a standard tank selector valve, all the ones Ive seen are the same, as is the plug and wiring. The problem is my dash switch is confusing me. First being, if the flashing wires are the sending units, how are they flashing when there is no wires on the tanks yet? What are they hooked too, its been propane for 40 years, the tanks were removed, and there is only one single wire for the gas gauge off the propane tank? Im thinking the black white wire off the switch will power the valve back and forth, But which wire do I hook it too, D or E , because in one position D or E will not have power then, and then the pump wont run.(In my single pump format for both tanks) That said, with a single pump, the pump goes on the engine side of the valve, on the dual pumps they go before the valve on the tank side. So does that mean I use the Red swich wire to power the pump, since its on in both postions, keeping the pump running both ways, and just hook the black white to the valve to move the valve, in that case do I use D or E?? That said do D and E both get power to move the valve? Or is my theory correct that when the Black White wire goes dead, the valve will move back. If not, I guess I will have to rig a relay in that line so when the black white wire goes dead, the relay switches power to the other line D or E? That way both lines can have power but not at the same time??? If this sound right to everyone, I'll try that
Then C and A assume will hook to one of the terminals on each tank sender, and B I can just hook to the single gauge wire thats already there from the propane tank since I know it goes to the gauge.??
What do I do with the other tank sender terminals? Are they grounds and just ground to the chassis? If so , how do I know which terminal is positive, and which is negative. They are not marked?
This all makes my dash switch only use 2 wires, the red and black white. The other three wires are the flashers? guess I just leave them alone and do nothing with them since I havnt a clue were they go or how they work??
A diagram for my truck would be nice.
Thanks in advance

 

With out looking up the wiring, sorry I dont have that, but I can tell you the flashing wires are the senders but they are not coming from the tanks but from the dash cluster.

Power goes into a Instrument voltage regulator (IVR).
This regulator turns on and off the power to maintain about 5 to 6 volts and where the flashing comes from.
It comes out of the iVR to the fuel gauge and out of it to a single tank or if dual tanks to the switch and then to the tanks.
The senders are a variable resister and grounded on 1 side.
So if you were to take the flashing wire at the tank(s) and ground it and turn the key on the gauge should go to full if the wiring is good.
Do not leave the key on too long and grounded as it can hurt the gauge.

I also think you are right on the BL/W wire being power to the switch valve on the frame.
By default (no power) the valve is on the rear tank. Put power to the valve and it goes to the front tank.

So the dash switch does the frame valve switch & the fuel gauge switching.
Dave ----

 

Thanks for that info. Makes the gauge wiring more complicated, but at least I know were they go. I've actually discovered that the valve needs the polarity reversed to work. Meaning D ad E wires are positive and negative for one tank, then reversed negative positive to move the valve the other way. So the stock valve was different if it moved by losing power, then moved back by gaining power. So after much looking online I discovered a DPDT relay will make that happen running off the black wire. That solves the valve part. The gauge stuff confuses the heck out of me, so I think I can dumby rig it wiring it into the valve, or I did find some wires cut by were the old tank was, new one now, one of them a blue one that was the propane tank gas gauge. It was one wire, no ground, cause I think it grounds to the tank. So my dumby rig would be use that wire as my gauge wire and connect it to the B wire on the valve for the gauge. Then put A an C onto the corresponding tanks to get the signal from which ever one its switched to on the valve, as the manufacturer suggests. Thus eliminating the chassis wiring except for that one blue gauge wire that was on the propane tank gauge. Tomorrow I'm going to test the other 2 wires I found taped off in that spot, they may be the tank signal wires. If so I will re attach those directly to the tanks rather than use the valve wires. But I dont think they are signal wires just guessing, because why would that one gauge wire be there if it had two signal wires going to the gauge already. Makes the blue one redundant. Still would need to determine which terminals to use on the tanks, but one way should read empty at the moment, the other will read full when its empty now. So hopefully thats true and makes this easier. LOL. Off to Gescan tomorrow to get a DPDT 12v 30a 8 post relay.

 

I for got you are using their tank switching valve and not the factory one on the Frama.

I figured if you knew how the factory set up worked you could figure out how to wire it up.
Good luck
Dave. ----

 

Here's the diagram for your truck's original switch. Just leave the gauge wires alone and original. Just hook the brown white to your new relay (the wire colors change and fade over the years).