I have been fighting a mpg drop in my truck for awhile now. On top of this i now seem to have an issue of how much fuel is going in the tank. I have normally used the same pump and just used 3 or 4 clicks off to try to be consistent. So this weekend after a 300 plus mile trip i clicked the pump off about 4 times and it seemed to show about the amount of fuel id expect to use in the trip, 15.8 gallons. I have the big tank and my gauge showed a bit over half a tank left. But it seemed like it still can take more fuel so i now feel i have lost any accuracy in my measurement. So for my next trip here of a long highway miles, should i try filling up differently? Do some of you guys try to fill the tank all the way up untill you can see the fuel? Thanks Joe

 

The MOST accurate way is to fill "to the neck". Keep filling until you can see the fuel in the fill neck. You have to go slow. Expect to spend an extra 5-10 excruciatingly slow mins at the pump manually holding the pump on.

 

I top the tank off to where i can see the fuel just below the cap threads. I keep it as consistent as possible and haven't noticed any ill effects so far.

 

I just fill to the click each time. Yes its not as accurate from fill up to fill up, but when you average the MPG across several fill ups you will get the same result regardless of when you stop the pump.

 

Take a look at the in tank mods, I don't have any links. I believe it allows you to fill up more completely. I haven't done it yet but it is on my to do list.

 

Harpoon mod cut my time to fill to the neck from 5+ minutes from click to ~30 seconds.
Welcome to guzzle's In-tank Harpoon Mod Web Page

 

How long have you have your truck? Do you know that you can get 5 gals more in it by a slow dribble method. The breather tubes are stuck into the tank about 3 or so inches and the foam will shut the pump off. Takes about 5-10 minutes longer to get the tank fully full by the dribble method but you can a better fuel mileage reading and less stops with the extra 75 or so range.

 

Thanks for the thoughts men. Yes using the click off method seems to have worked ok in the past. For a long trip at the end of the month i will try filling up into the neck. I will have a time for a repeat trip to compare mpg from the past.
I have had my truck since brand new. I was not aware that you can get several more gallons in it by dribbling the fuel in. I have allways understood that it is the 38 gallon tank and it has seemed right in the past when i have been able to get 35 in. So because of the vents does the dribble in fill trick actually allow you to get more then the rated 38 gallons of the tank? Or just get it totallly filled? Thanks Joe

 

On my truck after the first shut off click, if I dribble I can add another 5 gallons as someone already noted. It takes about 20 minutes to get it all the way to the top where I can see it. It is a pain in the behind, but is the only way to ACCURATELY calculate mileage.

 

Use same gas station, Same pump. Half tank of fuel. (pump speed, same truck angle,same foam in tank)

Full speed on nozzle until (click). Wait 20 seconds(cell phone stop watch). Full Speed, (click).. Hang up nozzle.
Drive approx 200 miles. (my half tank worth).

3 weeks Straight (3 fill ups) i got 17.5 MPG's (17.2) (17.6) (17.5).. calculated, back road country driving with a couple villages to pass through, heading to and from work. .. What are the chances? Was going for a 4th but topped off for a myrtle beach trip in a few days.

Just be consistent, That is all you can do.. Trying to get it full to the brim is insane. Consistent is key.