Anyone recognize this fuel sender wiring?

[Wincks2]

My fuel sender has three wires. Black, yellow, and pink-white.

As none of my books show this wiring, not sure what year it is from or what they are for.

My book says my fuel sending unit should have one grounded to the frame and another going to the fuel gauge. I think those are the black and pink-white respectively. Have been unable to find any info about the yellow wire.

It has been running my 6.2 diesel. Although a prior owner had left the middle tube unconnected so when I filled it right up, fuel poured out the middle tube and down the tank's side. My book says the tube should be connected to a vapor canister to prevent fuel fumes from getting into the air. My other book calls it a fuel syphon tube.


[IMG][/IMG] My book says it is a fuel syphon tube. But I haven't learned what I should connect it to.
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[hatzie]

It looks like you have Black, Pink/White, and Tan wires.
Black is ground Pink/White is the sender, and Tan is the in-tank fuel pump on the 1987-91 R/V series squares with TBI and dual tanks.
The Center hose connection is likely the vapor canister connection.

[Wincks2]

Thanks!

I'd been using a diagram with wire colors matching those on my fuel tank selector valve and meter switch. Prior owner must have used a different sending unit with a fuel pump in the tank.

As fuel's been getting to the engine fine, the in-tank fuel pump must not be necessary on my truck. Could I just end the tan wire, connect the black one to frame for ground, and connect the pinkwhite one to fuel gauge?


My book shows vapour canister locations for several engines but not one for the 6.2 diesel. If the 6.2 doesn't use a vapour canister, maybe that is why he left the third tube unconnected. Could I just cap it? Without capping it diesel fuel pours out the third tube whenever I fill the tank. Would stopping the fumes from leaving the tank cause a problem? Or could I use a diesel filler neck cap that I've read is vented to allow the venting instead of venting through the third tube?

[Wincks2]

Took the sending unit out of the tank and it is a diesel sending unit from the year 82-83, the only year they made them with a third wire for a water in fuel light. The third Tube went down to t he bottom of the tank. The top was connected to a tube that tan along the frame toward the rear of the truck and connected to a petcock to allow draining water from the tank.
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[hatzie]

Originally Posted by Wincks2

Took the sending unit out of the tank and it is a diesel sending unit from the year 82-83, the only year they made them with a third wire for a water in fuel light. The third Tube went down to t he bottom of the tank. The top was connected to a tube that tan along the frame toward the rear of the truck and connected to a petcock to allow draining water from the tank.
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Interesting. I assumed the WIF light was on the fuel filter housing like my 2000. I don't have GM wiring manuals past 1980 with the exception of the 1989 R/V wiring manual.
Are the drain valves still inside the spring hangers? I might be tempted to hook em back up if they are.

[Wincks2]

Not sure where it goes. There are photos and a diagram in this diesel place thread http://www.dieselplace.com/forum/sho...=434859&page=3 you may be able to tell from the diagram if the location is inside the spring hangers. I thought it was on the frame.
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[hatzie]

This video shows the drains in use on an 82.

Youtube - How to drain fuel tanks on a 1982...

[Wincks2]

Thanks!

Wish I'd known a couple of days ago I could start a syphon by blowing into the tube rather than sucking.
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