Pickles_99

I put in a new fuel pump, gas tank, sending unit, lines and I rebuilt carb. Runs perfect. . .for the first 10 or so gallons. When the tank only has about 2 gallons of gas in it, no gas to carb. Before I replaced the tank and fuel pump, the same thing would happen with the old parts. Only thing I can think of is the sending unit is not in the right place, so the fuel is dropping below the nozzle in the tank? What are the odds that I put the new parts in EXACTLY the same way as the original parts and now duplicating results? It seemed like the sending unit only fit into the tank one way?

This is the kind of thing that keeps me up at night!

66' 289 2B.

67mustang302

That's normal, the pickup needs clearance from the bottom of the tank to pull fuel properly; so you can never access the last bit of fuel at the bottom.

You should never run with less than 1/4 of a tank in any car, especially if it's EFI.

Pickles_99

No kidding. Thanks for the info. My gas gauge isn't working yet, so I'll have to pay better attention to how much is in the tank until I get to that project!

67mustang302

Ideally, you want to stay above half a tank; 1/4 is bare minimum and at that point, the remaining 1/4 tank should be considered emergency reserve.

On a carb it's not as bad with a mech. pump, since the float bowl will have fuel in it to cover quick little transients when the pickup is uncovered, but it's still not good for the pump. On EFI, it will frequently causes severe damage or destruction to the pumps. Carb with an electric pump is same as EFI in terms of pump damage. In either case it's not good for the pump.

In both cases it makes it easier for trash to get pulled up into the fuel system and clog things up. Ideally a tank would be clean, but sediment accumulates over time. The lower the fuel level the higher the sediment concentration so it gets picked up easier.

TexasAxMan

I've run out of gas twice in 20 miles of total driving. Don't go below 1/4 tank and you won't have that problem.

Hook up the gauge and don't be ignorant like me, I finally hooked mine up.