Fuel/sending units???

[flesh]

I see a lot of posts about this.According to the ones i've read,the fuel tank(reserve) underneath has no way to read how much fuel is in it? And the one behind the seat does? I have just bought a '72 camper special.The "floor" switch has been disconnected and a "under dash" has been installed.The tank behind the seat does not read.I have pulled the unit and checked the float, it floats.I have tried the "test" they describe in the tech article.Nothing still.Now my "reserve" tank(underneath) will read only a little with a full tank. I have read many posts about this and NOW, i'm confused??????? I'm a simple man, I just want these tanks to work. Is the switch wired wrong, should I try the dash adjustment, replace the sending units(or unit)??I'm making a trip from Wash. state to Ill. at the end of this month.Trying to get these little things all wrapped up before I go.

[TNIceWolf]

It would be a good thing to know how the plumbing from the fuel pump back to the tanks is routed. If the floor switch....is disconnected someone has been monkeying around with the fuel lines for some reason . Making sure the fuel supply from each tank is actually reaching the fuel pump would be a good first step. Once you figure out what is going on with the lines then you can attack the secondary issue of what is going on with the electrical side of the system. I would be curious to see a pic of the underdash switch. It could be useful to know whether it is a factory type or an aftermarket add on that might work differently than the original.

[colnago]

First, I agree with TNIceWolf; first things first. If everything rings out, after you check the basics, pull the sending unit from the main tank. Check it with an ohmeter. I forget the range you should be seeing, but it's specified in the tech sections. It's possible you got a sending unit from another truck, which doesn't have the same range as the Ford units. Next, hook it up to the truck wiring, and move it manually up and down to see if the gauge tracks the movement. If it's still good, then you might have to bend the arm to set the float at the right level in the tank. I just went through this with my truck. Now, after a year of owning the truck, I now have a functioning fuel gauge!

Also, I don't think the valve under the seat has anything to do with the gauge (at least, it doesn't on my '67 Camper Special). As far as I know, it just controls the plumbing. Mine was completely bypassed by the PO (which is fine for now, because he also removed the aux tank). He also bypassed the switch, which really confused me when I was first having problems with the fuel gauge!

If all else fails, and you absolutely, positively have to take the truck on your road trip, make sure the main tank is plumbed to the engine. Fill it up (19.5 gallons, I believe). Write your mileage down. After 100 miles, take the fuel sender off, and manually check your fuel level (either by using a flashlight, or a long dowel/ruler). That will at least give you an idea of how far you can drive before needing to stop for a refill. And take an extra 5-gallon jug of fuel in the back, just in case. Been there, done that. Long drive through the desert between Barstow, CA and Bullhead City, AZ, and not a lot of gas stations.

By the way, the tech article on the fuel sending unit is here:

http://www.fordification.com/tech/fuel- ... -units.htm

Joseph