Tundra 38 Gallon Tank Upgrade

mercurytech84 · Aug 23, 2017

Hello All,
I have recently purchased my new 17' Tundra SR5 CM from a dealer in AZ. I was talked into the SR5 package that included an upgraded 38 gallon fuel tank. Last week, I ran the tank down to ''24 miles to empty'' and decided it was time to fill up. lol. Normally I never run it down below 1/2.
Anyway, when I filled up, the pump said I only put 29 gallons in. I even tried to top it off, put the tank was indeed full, and the gauge also said so.

My question is, am I loosing my mind, or was I really supposed to put about 36-37 gallon of fuel in the tank based on the ''38 gallon fuel tank upgrade'' I was sold? A couple of people (not on here) told me that maybe there is a 10 gallon reserve on the tank? I called BS on that, but any thoughts?

gosolo · Aug 23, 2017

Yes it is"reserve". There's many threads about this, if you choose to search. You easily could go another 100+ miles. Live with it or sell the truck.
The best explanation for why Toyota did this, is that there's a need for some gas to slosh around the fuel pump to prevent it over heating.

joonbug · Aug 23, 2017

Yes it's normal. BS... but normal.

https://www.tundras.com/posts/244842/

And don't ever top off on our trucks.

ColoradoTJ · Aug 23, 2017

Yep, you have a big reserve.

The 26 gallon tanks would show 0 miles until empty and still have 5-6 gallons of gas.

So to answer your next question that you're going to ask (why did Toyota do that), is so that you don't run out of fuel. -Most auto manufacturers include roadside assistance for a set amount of time. I wouldn't want to come bring anyone 5 gallons of fuel.
Recently, I almost ran out of fuel in SD in the middle of BFE. I also have a 36 gallon tank. I am deciding if I want to go with a Titan tank or just use an auxiliary tank in the bed. Both have benefits...mainly haveing more fuel. I would like to have 58-65 gallons of fuel.
-Running a modern fuel injection system out of fuel is never a good thing and could do some damage. I was test driving a sports car (91 Camaro) and told the salesman it was very low on fuel. He said don't worry about it, "it has a reserve", and off I went. 5 miles down the road it ran out. It did around 1200.00 in damage (or so I was told) since I couldn't purchase the car for a week. This time it had a full tank when I went to test drive the car.

You have a bigger reserve tank than most, but if you plan on towing something more than 4K lbs, trust me, sooner than later you will find out how great it is to have it.

zcarpenter92 · Aug 23, 2017

gosolo said: ↑

Yes it is"reserve". There's many threads about this, if you choose to search. You easily could go another 100+ miles. Live with it or sell the truck.
The best explanation for why Toyota did this, is that there's a need for some gas to slosh around the fuel pump to prevent it over heating.
Click to expand...

This

Jagamov · Aug 23, 2017

joonbug said: ↑

And don't ever top off on our trucks.
Click to expand...

What do you mean by this?

Thanks.

joonbug · Aug 23, 2017

Jagamov said: ↑

What do you mean by this?

Thanks.
Click to expand...

If the gas overflows, it can spill into the charcoal canister. $1k repair. It's happened to a few people here. Just stop filling when the pump clicks as a precaution.

Jagamov · Aug 23, 2017

joonbug said: ↑

If the gas overflows, it can spill into the charcoal canister. $1k repair. It's happened to a few people here. Just stop filling when the pump clicks as a precaution.
Click to expand...

Wow...Good to know. Thanks!

TheBeast · Aug 23, 2017

mmmm..gasoline

if you filled up 29 gal, you have the 38gal tank.

mercurytech84 · Aug 23, 2017

Thanks for all of the useful info guys. I learned alot today.

Spvrtan · Aug 23, 2017

joonbug said: ↑

If the gas overflows, it can spill into the charcoal canister. $1k repair. It's happened to a few people here. Just stop filling when the pump clicks as a precaution.
Click to expand...

Damn.. honestly didn't even know that could happen. I normally force another click or two in bursts of gas down the neck after the pump stops.

Vendeta2k · Aug 23, 2017

Learning all sorts of useful stuff on this site! Thanks for the info!

BlueFalconActual · Aug 23, 2017

joonbug said: ↑

If the gas overflows, it can spill into the charcoal canister. $1k repair. It's happened to a few people here. Just stop filling when the pump clicks as a precaution.
Click to expand...

I am one of those people. Lot attendant did it when I bought it new. Wanted to be mad it was just a teenage kid trying to hook me up with more fuel.

PMG · Aug 23, 2017

What happens and is the effect immediate?

Black Wolf · Aug 23, 2017

ColoradoTJ said: ↑

Yep, you have a big reserve.

The 26 gallon tanks would show 0 miles until empty and still have 5-6 gallons of gas.

So to answer your next question that you're going to ask (why did Toyota do that), is so that you don't run out of fuel. -Most auto manufacturers include roadside assistance for a set amount of time. I wouldn't want to come bring anyone 5 gallons of fuel.
Recently, I almost ran out of fuel in SD in the middle of BFE. I also have a 36 gallon tank. I am deciding if I want to go with a Titan tank or just use an auxiliary tank in the bed. Both have benefits...mainly haveing more fuel. I would like to have 58-65 gallons of fuel.
-Running a modern fuel injection system out of fuel is never a good thing and could do some damage. I was test driving a sports car (91 Camaro) and told the salesman it was very low on fuel. He said don't worry about it, "it has a reserve", and off I went. 5 miles down the road it ran out. It did around 1200.00 in damage (or so I was told) since I couldn't purchase the car for a week. This time it had a full tank when I went to test drive the car.

You have a bigger reserve tank than most, but if you plan on towing something more than 4K lbs, trust me, sooner than later you will find out how great it is to have it.
Click to expand...

I personally like having the 6 gallon reserve especially in BFE-AK he...heh.

5280Tundra · Aug 23, 2017

Anyone know why my mileage till empty was around 560 then dropped to 540 and then dropped to 520?

BlueFalconActual · Aug 23, 2017

PMG said: ↑

What happens and is the effect immediate?
Click to expand...

CEL comes on.

Quartermeter · Sep 1, 2017

5280Tundra said: ↑

Anyone know why my mileage till empty was around 560 then dropped to 540 and then dropped to 520?
Click to expand...

What kind of time frame are we talking about? If its since you bought it then your avg. mpg has gone down.

MotoTundra · Sep 1, 2017

joonbug said: ↑

If the gas overflows, it can spill into the charcoal canister. $1k repair. It's happened to a few people here. Just stop filling when the pump clicks as a precaution.
Click to expand...

But I prepay with cash and love getting it to an even dollar haha. No more of that!

Seriously though, great info, I somehow missed that. Thanks.

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