Help with gas needle in 79 Ford F150

[ErwinRommel]

Well my gas needle reads empty all the time. It will go up slow to the E when I crank the truck up then stays on E.

Well before I put the new truck bed I got on the back. I saw that there was a line that wasn't hooked up to the rubber piece thats on top of the gas tank. I wonder if this is the line that resends the gas back in the tank from the carb. My carb always wants to flood when I crank it up sometimes.

So I hooked the line up but still nothing.


Well anyways about the gas needle. I unpluged the sending unit and flipped it around and the needle went over the Full line.

So I don't know if it could be the sending unit is bad or what.

Any ideas?

[BernieB]

There's no line that sends gas back to the tank.

As for the gauge, how full is the tank?

[ErwinRommel]

Originally Posted by BernieB

There's no line that sends gas back to the tank.

As for the gauge, how full is the tank?

Well why is there another line that is unhooked from the top piece then (it should be hooked up). What's it for then? Reserve?


Idk how full the tank is because the needle doesn't tell me.

I know it ain't empty. I went to go get gas and it still stays on E.

[BernieB]

Probably the tank vent, or to the evap cannister.

I asked about the gas in the tank to get an idea of what the gauge should be reading. Can you get a resistance reading on the sending unit?

[ErwinRommel]

Originally Posted by BernieB

Probably the tank vent, or to the evap cannister.

I asked about the gas in the tank to get an idea of what the gauge should be reading. Can you get a resistance reading on the sending unit?

Tank vent? Evap cannister?

Eh, it's a 19 gallon tank. I put like 3-6 gallons in it.

Resistance reading?

Do I need an electrical tester? lol. Sorry, the picture is in my head of what I think yer talking about.

[bubbatrucklover]

Originally Posted by ErwinRommel

Tank vent? Evap cannister?

Eh, it's a 19 gallon tank. I put like 3-6 gallons in it.

Resistance reading?

Do I need an electrical tester? lol. Sorry, the picture is in my head of what I think yer talking about.

I think he means the "coffee can" (or what we used to call it) it's the black plastic tank under the hood that has like carbon filter or something in it.

[bubbatrucklover]

Here's an "official explanation":

An evaporative canister is part of the evaporative system that is within the emission system. Hydrocarbons are a form of pollution that gasoline releases as it evaporates or after is is burned. While fuel is stored inside the tank, fumes build up and are retained inside this canister. The canister contains charcoal that absorbs the hydrocarbons. When the engine is started, a valve opens that allows fresh air to come in and purge the fumes (hydrocarbons) into the air intake and then into the combustion chamber for burning. I understand that more hydrocarbons are released into the atmosphere by leaving your fuel cap off, than what comes out of your tailpipe while the engine runs. If there is a leak anywhere in the evaporative system, such as a bad hose, canister leak or leaving the fuel cap loose, the check engine light will set.

[bubbatrucklover]

Don't know if this helps but:

How to Check a Fuel Sending Unit | eHow.com

[Towtruck]

check the float on the sending unit it might have a pinhole leak in it causing it till up with fuel. this would definatly cause the float not to float but sink therefor no reading on the guage