I purchased a good solid 89 F250 over the weekend. Drove 250+ miles to pick it up and trailered it home. It has several issues which I am sure can be solved with help from this forum.

The fuel gauge doesn't register correctly. When I test drove and then loaded up the truck the fuel selector switch was on the front tank which showed maybe a little less that 1/4 tank. I switched the selector to the other tank and the gauge pegged past the full mark, flipping the selector back to the front tank, the needle dropped back to 1/4 tank.

I filled the front tank this afternoon on the way to registering the truck, the gauge still showed less than 1/4 tank and needle continued to move to empty as I drove it around. I don't know if any diesel is in the rear tank and with the prices I am hesitant to just fill it up until I know what going on with the fuel gauge and/or selector.

Any advice/help would be very appreciated in troubleshooting this first of many problems I have in front of me. I would think that both fuel sending units would be bad, but I don't know what the PO had done or not done either.

hugger94

 

Here is a very stupid question.... there is nothing visual to show whether or not the black plastic rocker switch is on the front tank or rear. I just went out and checked again. The rocker switch is in the down position which on my 84 F250 indicates it is on the rear tank. The PO didn't have the owners manual so I am guessing that maybe my thought that I was on the front tank is not correct.

If I am truly on the rear tank it would make sense that the gauge didn't move when I filled the front tank and when I flipped to the other tank I was really seeing the front tank which should have been full.

OKay, if maybe this is not a problem. Hopefully someone will have a owners manual and can confirm if the rocker switch is up for front and down for rear tank.

Thanks again.

hugger94

 

Down should be rear, up should be front.

With the rocker, when the top is in, you should be on the front.
When the bottom is in, you should be on the rear.

 

Sorry, I should have looked at the switch again before posting the first time.

I was in total panic mode when I didn't see any change in the fuel gauge after filling up the front tank.... Yes, the bottom side of the rocker switch was down so it was on the rear tank.... Guess I will have to put some fuel in the rear tank and watch the gauge come up.

Thanks Dave for confirming what I finally was realizing after my initial post.

Hugger94

 

With the rocker switch on the front tank the fuel gauge is buried pass the full mark. With the rocker switch on the rear tank the gauge appears to register correctly.

How do I isolate the problem with the front tank, sending unit or float?

Any help will be greatly appreciated.

I will be posting often as it appears I have a few other things that need to fixed as well like the brakes not working properly and the C6 wanting to slip after it has been driven for a few miles.