Which way does gas gauge float install?

[jagarra]

I put a new tank in my truck, when I installed the float assembly I put the longer portion of the float facing toward the rear of the truck. Problem is that my gauge says it is full, but I only put 5 gals in the truck.
Could it be the float is rubbing against the tank and not moving???
All the troubleshooting advise in the manuals indicates empty as an indication it is not working right, not full.

[jrmunn]

Jagarra,

What kind of tank do you have? Mine is behind the seat. My recollection is that the fuel pickup line and the fuel level mechanism are on the same assembly that only goes in one way. But I did need to bend the fuel pickup line so that it would fit, and my fuel gauge tends to read on the high side.

JRMunn

[jagarra]

I guess I didn't explain the question clear enough. The brass float can be attached to the pick up wire in 2 directions, from the pictures I have seen the off set groove is closest to the front while the larger area is pointed toward the back.

In discussing the gauge not working my friend and I concluded that the wire from the gauge or the float itself must be grounded, giving me the full indication. From what I gather 12v is supplied the gauge on the panel, it then goes to the float assembly which is a big variable resistor and then to ground. The position of the float ( based on how much fuel is in the tank) will cause a different voltage drop which will effect the position of the needle on the gauge. Since I am stuck on full, it seems I am grounded somewhere in the path to the float.

[jrmunn]

Jagarra,

And I should have read more closely. The new fuel pickup and fuel level mechanism I installed came with the float attached, so I didn't check on the direction it should be facing. But it does seem to "stick" after filling and needs some bumps to come down as the fuel level drops.

Checking for a short sounds reasonable, but I can't remember whether there is supposed to be low resistance with the tank full or empty. The connection at the tank is supposed to be insulated, so (assuming that you are correct about low resistance when the tank is full) I would start there to make sure the float mechanism itself isn't shorted out. I think this would involve disconnecting the wire to the gauge, then measuring the resistance between the tank wire post and a clean ground.

I can also imagine a short in the wire from the tank to the gauge. In my truck, this wire runs under the threshold on the drivers side and then under the mat next to the side panel, so there are numerous opportunities for wear and weathering.

Good luck. I know it doesn't help you, but it is good to know that I am not the only one to discover new problems when trying to fix the obvious ones. It seems that these trucks were built to withstand rough treatment in the short term with most problems coming from time and exposure.

JRMunn

[jagarra]

Yes, you are correct in that when the gauge is registering a full tank it still has a resistance. When I was checking the original float on the bench after I cleaned it I could get a varying resistance in the entire range. The most when empty, diminishing as the float went to the top.
My concern is that when the whole assembly is installed, the float itself will rub against the tank and give you a false reading. If the wiring to the gauge checks out, I guess the next step it to pull the float assembly. Reshape the wire and try again.


Again you are really correct about one repair leading to another. Rebuilt the master cylinder and started checking the wheel cylinders, they were so gunked up that I am rebuilding every wheel.

then the window channels, found I was missing a rear channel guide in the driver's door, found one on e-bay.

Keeps me occupied, having a great time at that.

cheers,