I read several posts on fuel gauges before posting but did not see anyone with the same issue I am having.

::Truck Info::
1992 F-250 XLT 4x4 Ext Cab Long Bed
460 gas engine
5 spd manual
137k miles.

::Fuel Gauge Issue::
Both of my fuel tanks report inaccurate fuel levels. When I fill up they both show full, however they drop to E when there is still quite a bit of fuel left in the tanks. I took my truck camping shortly after I purchased it and the tank dropped off so fast I thought my mileage was really really bad, when I filled up the truck only took 10 gallons so the gauge was reporting empty when the tank was around half full. The front tank also reports empty when there is still quite a bit of fuel left in it but I don't have the exact gallon info for the front tank.

I have only owned this truck for a short time and am in the process of running the tanks dry and filling them up to record the mileage I can expect from each tank so I can use the odometer to track fuel use. While this solution works for me, if it's not too complicated or expensive to fix this I would prefer the gauges work as designed.

I can swap from my front to my rear tank without issue. Based on what I have read so far I suspect the sending unit or float is the culprit here, but if someone can confirm one or the other based on this info that would help me fix this faster and easier.

Thanks in Advance for your suggestions.

 

This sounds almost exactly like mine. depending on driving I get anywhere from 300-400km per tank. Both say empty by 200-250. I just run one dry then fill up when the next one hits the E.

My (possibly wrong) understanding was it is an issue with the sender being pessimistic so it's not an easy/cheap fix.

 

My 88 F150 dual tanks had a simlar issue. Full was full and then somewhere in between the selected gauge would usually bounce from empty to full for a while then stay on empty. Later I had fuel pump issues and truck sat in yard for a long time. I first tried to trace the issue at the switch since both tanks did the same thing. To make a 3 fuel pump story short, I finally got aggravated with the guy trying to fix it and did it myself. I pulled the midship tank, pulled out a very rusty fuel pump/sending unit combo from a very rusty tank. Ordered a tank and 4th pump from Autozone and problem solved after replacing the transfer switch too. The other tank I assumed was in the same shape.... and will continue to be that way (off). Had the pump not looked so bad, I probably would have monkeyed with the sending unit which may have just needed some cleaning. Kind of a flimsy design if you ask me.

Now your next unasked question... to remove the bed or not remove the bed to access the pumps. I pondered this one for a while too. I opted to drop the emptied tank with jacks and boards, which was probably a lucky decision since I had to replace the tank anyway. Looking back if I had to do it again, and was doing both tanks at the same time, I probably would have removed the bed and kept my fingers crossed on the tank condition. Don't know if the rusty tank lead to quick damage to the earlier pump or I got scammed on "new pumps", but with all the labor to drop the tank, I figured I'd rather put in a new tank than risk having to replace the pump again. Its been 2ish years and pump and gauge work fine.

 

The fuel sending unit floats are probly full of gas. On my truck I had to empty them and resolder them as they are brass floats. It probly will be better to replace them insted if your not good at soldering.

Also if the sending units/pumps are rusted up, better to replace them as trying to fix is not worth it(been there and done that).

For me I pull the bed off the truck, 6 bolts and one wire connector and 2 fuel fillers. With a friend, just 2 of us can move a bed off. That opens up everything for easy fix.

 

Thanks for the tips guys. I think I will opt to pull the bed as it will give me a chance to inspect everything else on the rear chassis. It takes me a while to trust vehicles after a purchase and while this ford has been great so far I would like to see it in more detail anyway.


Thanks again.

 

im going to agree. its sounds like the sending unit is malfunctioning or your floats are just full of gas. taking off the bed would be easier to access them. let us know if this helped.

 

Spray the bed bolts down with some PB blaster or equ. That will help in getting the bolts off. Just hope they don't spin in the bed! If that happens, the fun will begin getting them off.