Gas tank size says 21 gallons but...

When I'm at a quarter of a tank I put in an average of 12 gallons. Is there a huge reserve or does they gage in the tank sit higher than the bottom

 

The fuel gauge is an approximation. Your range is an estimation. You are literally being gaslit by your gas gauge.

 

Every time I've run to the light comes on it takes about 19 gallons so 2+ gallon reserve from light. I know within 40 miles I need gas lol

 

It's a 21 gallon tank.
3 gallons of it is reserve.

 

When I pull into a station (the gas light usually on) I’m usually buying 20 gallons of gas to filler up.

 

I've gone 35 miles past 0 miles left (on purpose) and it still only took 19.5 gallons.

Need to get me a jerry can and see how far it can really go

 

I’d go with the spec. I try never to have the light for low fuel go on. Any dirt/slug that you pumped in will be used. I also NEVER go to a station that a fuel truck That is dumping gas.

 

How does the slug know to stay away from the fuel pump the rest of the time?

 

My personal best is 20.2 gallons

 

To be fair, the fuel pump pulls from the bottom of the tank anyways so that would make me assume any sludge at the bottom is already getting sucked in regardless of how full the tank is.

 

Try filling up and watch the gas gauge not move from full.

 

The 21 gallon tank is real; on several occasions I have filled up and hit over 20 gallons, always to the pump click-off, never to the brim (this is very harmful to the EVAP system).

 

Well if you have 10gallons of gas and 1/2 gallon of followed fuel or 4 gallons of fuel the proportion is likely favor the larger amount. Also do you believe the fuel pump is flat with the tank or slightlY raised. What ever you want to do it’s your truck.

 

Facts. Both of those are common and oft repeated misconceptions.
The fuel pump being in a well at the bottom of the tank also means it is always submerged, but the “running your tank to E will overheat the pump” camp still insists

 

I had to troll my logs:

 

I run a scanguage and get the real % readout from the tank float. Lowest I've been is about 9% and no "range" on the dash and still filled up under 20gal.

 

in my hypermiling journey to get a 400mi tank; i used my average MPG of like 19.8 and calculated that after the "0 miles to empty" popped up, i would have juuuuust about 60mi until i was actually empty. that roughly worked out because i remember the tank took about 20.8 gals for 41mi. YMMV, obviously, but it was a fun stress test to see how many miles i could get out of a tank.

 

seven eleven always delivers more than you bargain for, right ;-)

 

Not my usual stop, I’m going to guess I was desperate. Tank confirms that. Lol.

 

When gauge shows quarter or less left, I go get gas. No stress, no headaches, just fill'er up and get on with life.