I have long heard that if you "fill up" the gas tank to the top of the neck, you can have problems...

Has anyone else heard this, or experienced...

Please elaborate...

I'm trying to determine, how much is too much gas to put in the truck



Thanks
Dan

 

I have heard it before. I believe there is a concern with the evap system (used to be a charcoal canister don't know if they still have them) being contaminated with liquid fuel rather than just fumes. Any way, I'ved always filled mine up right to the top of the neck and never had a problem. I know the gas stations don't want people pumping it up that high because of the risk of spillage.

 

Just to let ya know. I fill mine up to the top all the time. I never had any problems. I fill to the top to get an accurate mpg reading. That is 17-19 mpg highway 2001 supercrew 4.6
One thing I have heard is to shut the truck off when filling the tank up. Sensor may detect no pressure in the tank over a period of time.

Is there anyone that knows of this?

Skip

 

I've got a long wide bed so that means I have the 30 gallon tank. I have noticed that if I use the autofill that when it clicks off *full* I can top off the tank with upto another 3 gallons. What is a full tank is therefore subjective IMO. Claims of gas milage are met with skepticsm from me unless proven over a long period of time.

For me filling the tank by topping it off is a pain in the butt. I used to do it but now I mostly go to the same local gas station all the time and fill it until it clicks off as full.

 

skipster,

Well, you should be shutting off the motor when filling up anyway, but I think it also has to do with resetting the gas gauge sending unit too. You probalby would get a CEL because the cap is off too.

dantheman1973,

As far as filling up to the top of the neck goes, I know that there is a return line from the fuel injection plumbing that will send gas back to the tank if it's not used (so there should be some room for it). Also, the evap system vents the tank and if gas gets into it, then it will just saturate it. Gas will also expand when it gets warm out and if it's really full, will start spilling out the neck. I've mostly just seen this on older cars with the rear license place filler, but it could still happen I'd think. (I think I read something about NOT filling to the top in the owners manual somewhere too??)

Not saying that any of this will all happen at once or that filling up to the top is a "bad" thing. I can see the point on wanting to compute gas mileage and all. I know how much my truck uses and can tell when it's not right. I just let the pump shut off and then 'bump' it a couple times to get the price to a round number like $29.00 or $29.50...........

 

Mitch150 is right on the mark with his post. Also the truck needs to be shut off becasue with the gas cap off and truck running it can trigger a CEL. Also the best way to determine gas milage is not to top off becasue you will not get the same amount of gas into the tank everytime doing it that way. The best thing to do is when the pumps shuts off on its own stop there and record the amount. The pump should shut off at about the ezact saem place evrytime you fill up. Filling the truck up to the point of the gas being up in the fill neck can cause problems with the fuel evap system.

Richard D.

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I find that if the nose of my truck is pointed downward when filling that it will put as much as 2 more gallons in that when it is sitting level. That's why I only believe mileage claims that involve several tankfulls in a row. The fills are just too inconsistent; even if you just let it click off. Not only is truck position a factor but not all pumps click off at the same point.