Can't the tank to fill up

[gapboi210]

Can't get the tank to fill up

I am absolutely sure that I am not getting a full tank of gas. When I fill up it is only taking about 13 gallons. The gauge will only go uo half way past 1/2. I am thinking it has to be some sort of venting issue. Where does the tank expel air as it fills with fuel? Any ideas?

 

[techno]

Im pretty sure the tank air is expelled through the same opening that the fuel goes in. I'll check the fsm tonight to confirm.
13 gallons sounds about right for the average fill up. I usually do between 12-15. I did do 16 once after running on E for 60+ miles.
How many miles are you getting roughly per tank (or your calculated mpg)?
As for the gauge only going to 3/4, not sure, an interesting twist on the issue, but might be unrelated.

 

[gapboi210]

i am getting about 180 miles per tank

 

[shootmymime]

well a few things you also have to think about,

1. you arent driving till you run out of gas right? there is about 2-3 gal of gas left in reserve.

2. and when u fill up, you can put about another gal in (like when you top off, there is still a few gal. space)

so you may only put in 13 gal into a 18 gal tank. so you can take away about 3-4 gal for extra space....


just my little 2 cents

 

[gapboi210]

There is definitly not a full tank of gas and the gauge is correct. I need to see how it vents etc

 

[techno]

Air from the tank should be expelled through the small diameter pipe as you can see on the upper filler pipe. Fuel going in goes down the big pipe and the air comes out of the small one. There is a fuel evaporation vent pipe, but that goes to the throttle body on the engine to burn the fumes during combustion.
I seriously doubt that your tank is pressurizing itself during filling, but one way to double check if you want would be to disconnect the evap hose when you fill up.

 

[gapboi210]

thanks techno for the pic, can u smap a pic of the hose ur talking about on the throttle?


much appreciated

 

[gapboi210]

just thought shouldn't I unplug it at the charcoal canister? if my canister is plugged it wouldnt help if i unhooked it at the throttle right?

 

[techno]

yes sorry, you are right, disconnect at the canister.

 

[Mr. Dabadina]

Another reminder of needing to get a FSM.

But I can only squeeze 15 gal. in my tank.

 

[shootmymime]

ok.. i ahve a question, i filled up 2 day and i hapend to look at the guage (2night) and see it rising from 3/4 a tank, some 5 hours later, i only put half a tank in, and ifs like a 5 min drive home from the station where i filled up, so it went to the top tehn back down

why does the gas guage move so much???


ahh i hate this

 

[gapboi210]

I looked at the canister and I noticed that there are 2 hose that come out of it going to metal return lines. One has a clamp and one doesn't. Anyone know which one I need to disconnect next time I try filling up?

 

[Mr. Dabadina]

You should of seen my buddies late 80s camaro. That gas gauge swayed back and forth like a boat in the ocean. If it swayed from empty to full after a quick turn he said he had a little more than a 1/3 of a tank. That would drive me nuts.

 

[techno]

This is the line from the fuel tank....

 

[gapboi210]

Thanks now I know. I noticed ur setup is a little different then mine. I dont have hose clamps and I don't have that service port witht the green tip. I wonder if my canister is bad and that is why I also have a rough idle.

 

[gapboi210]

hmmmm i got more fuel into it without discinnecting that line. I think my tank is full....but still have the same reading. 2 different sending units with identical readings. What could the float be hitting?