I have a 2000 B3000 truck with a gas leak only when I fill up - it's fine otherwise. I think I must have a crack in the gas tank cap or the filler neck . With it close to full I can't get it to leak either going up a steep hill or around a sharp curve. My gas gauge went out as well (I checked all 3 instrument cluster fuses). I have found used sending units for $100-if it's not the gauge. What's the easiest cheapest way to fix these issues-drop the tank and see what I find? My gas mileage is terrible (about 13mpg). Is this problem enough to account for that? This is my first post-glad to be on board. I do have codes for gross emission leak and bad O2 sensor. I may get sensors replaced with whatever else. Thanks

 

Advance auto parts shows to have the sending unit/hanger assembly without the pump for $82.00. The filler neck is on ebay for $44.00. You might find the assembly on Ebay much cheaper too. You will have to drop the tank or remove the bed to access it. It is unlikely that the gauge in the dash is bad.

 

I'm not familiar with the 1994 and newer trucks, just the made-in-Japan models. But check the gas cap for leaking, check all the fuel filler and related hoses.

On thise early trucks we loosen the mounting bolts for the bed on one side, remove the mounting bolts on the other side, then jack up the truck bed for access. I'd be surprised if you can't tell where the leak is or has been.

I assume you see spillage on the ground or smell it. And how's your fuel filter, typically mounted underneath on a frame rail?