Fuel tank selector valve wiring.

[wanabebig]

Alright, I switched the truck to a single rear tank, and bypassed the fuel selector valve on my 1985 F350. What I'm trying to figure out, is the wiring in the bundle that Goes from the selector valve to the guage. What wires do I need to put together to get my fuel gauge back to working?
Thanks.

 

[Shadetreemechanic]

Just google 1984 ford diesel selector switch wiring diagram. Then click the images tab. You will find your answer. I have wired these things several times but don't retain wire codes. They are easier to look up each time.

 

[79jasper]

Or search "manual tank selector valve" here. Many threads on it.

Sent from my SAMSUNG-SM-G890A using Tapatalk

 

[madpogue]

Or consult this diagram - http://userpages.chorus.net/elephant/FuelTankSelector1985.pdf - put a jumper wire between terminals 4 and 5 on the connector.

 

[wanabebig]

Thanks for the response, I have searched on google and found the image that Madpogue posted and went off of that and thought I had it, but it didn't do anything. I've also searched through the manual selector stuff and didn't find my answer, and nothing is working, that's why I came here to the guys with more knowledge than myself.

 

[Shadetreemechanic]

If nothing is working, then I would look elsewhere for the problem. Start by grounding the wire coming from the guage. It should then read full. If that works, then you know the guage itself is good so measure resistance on the wire coming from the sending unit to verify its operation. I have had best luck diagnosing sending units out of the tank where you can use a multimeter to see resistance change through the arch of the guage, but if its greater than 0 and less than 1 that should translate to a reading on the guage. If guage tests good, and sending unit tests good. problem is at FSV in your wiring.

 

[wanabebig]

so I've tested my fuel sender and it shows its working. But the wiring at the dash isn't getting things right, I don't think? I have the dash apart ohming wires at the back on the gauge cluster, what should I see there? Or what wires should I be checking? I thought I had this all understood and figured out but its just confusing me even more.

 

[madpogue]

Check resistance between the yellow/white wire at the cluster and ground. It should correspond to the level in the tank (high resistance empty tank, low resistance full tank). If not, then the problem is between that point and the tank; either the way you've bypassed the selector, or the wiring itself. If that looks good, check the VOLTAGE coming from that regulator on the cluster with the key in the RUN position. IIRC, that should be 5V. If not, then the regulator is suspect, but then I would also expect the other gauges to be inop. If you have 5V there, then the gauge head is the prime suspect.

 

[franklin2]

Put the dash wiring back together. Find the yellow/white wire coming from the fuel gauge in the dash. It should be under the truck at the old switching valve location. With the key in run, engine off, take this yellow/white wire and ground it to a good ground. The fuel gauge should swing to empty or full. Then take the wire off and let it hang in the air and touch nothing. The gauge should swing full scale opposite. If it passes this test, the wiring up front and the fuel gauge are working properly.