2010 Gas Tank - 60 Litre???

DCoop · October 5, 2020

My 2010 Yukon Denali seems to have a gas tank problem. I can fill it as fast as I want to so it's not a venting problem. My problem is that when the gauge reads 3/4 tank I can only put in 4 gallons (15 liters) at 1/2 tank it takes 8 gallons (30 liters) and down to a 1/4 tank only takes 12 Gallons (45 Liters) to fill it. I'm afraid to run it any lower due to the possibility of burning out the fuel pump, if it's not covered with gas. Everything I read says it should be a 23 gallon (90 liter) tank. I'm forever stopping to fill it up. I have measured the tank, it is 48" X 17" X 7".. that means it should hold the 23 gallons or 93 liters. BUT IT DOESN"T. The way the gas gauge reads max will be 15 gallons or 60 liters. The gas gauge reading to fill up ratio never varies so I don't think its a faulty gauge. Anyone have suggestions or have dealt with this problem??

CamGTP · October 5, 2020

Sounds like the fuel sending units level sensor is not working correctly if it's reading that far off.

The only real way to test it is to drop the tank so you can pull the pump. Then if you had two people you could move the float up and down to see how it displays on the dash.

It's really hard to overheat the pump because it's a returnless fuel system. The fuel that does not get used gets dumped straight back into the fuel bucket in a never ending cycle so the pump always has cool fuel around it.

DCoop · October 6, 2020

To: Senior Enthusiast, Thankyou for the info, I will have to drop the tank, I'd say that i'll let you know, but I just had it grease under coated, so I won't be doing that til next spring. DCoop

davester · October 7, 2020

...well, you can kill the pump by running the tank dry. I think that's what the O.P. is concerned with, that he isn't sure how "empty" he can get the tank, based on the gauge, without actually running it dry.

Ideally, you'd want to use a scan tool to get the readings that the bcm gets, as well as command the fuel level setting at the bcm to see how accurate the gauge matches what the bcm says it should be, so you at least know if the problem is between the fuel pump and the bcm, or the bcm and the gauge.

swathdiver · October 14, 2020

On 10/5/2020 at 4:22 PM, DCoop said:

My 2010 Yukon Denali seems to have a gas tank problem. I can fill it as fast as I want to so it's not a venting problem. My problem is that when the gauge reads 3/4 tank I can only put in 4 gallons (15 liters) at 1/2 tank it takes 8 gallons (30 liters) and down to a 1/4 tank only takes 12 Gallons (45 Liters) to fill it. I'm afraid to run it any lower due to the possibility of burning out the fuel pump, if it's not covered with gas. Everything I read says it should be a 23 gallon (90 liter) tank. I'm forever stopping to fill it up. I have measured the tank, it is 48" X 17" X 7".. that means it should hold the 23 gallons or 93 liters. BUT IT DOESN"T. The way the gas gauge reads max will be 15 gallons or 60 liters. The gas gauge reading to fill up ratio never varies so I don't think its a faulty gauge. Anyone have suggestions or have dealt with this problem??

Your tank has a 26 gallon capacity.

When the tank is on:

E = 0-13% fuel remaining or 0-3.1 gallons (2.5V or 197-250 ohms)

1/4 = 30-35% fuel remaining or 8.7 gallons (2.2V or 150-190 ohms)

1/2 = 50-55% fuel remaining or 13.5 gallons (1.6V or 118-140 ohms)

3/4 = 72-78% fuel remaining or 19.7 gallons (1.25V or 83-110 ohms)

F = 88-100% or 24.5 to 25.9 gallons (1.0V or 40-66 ohms)

Low Fuel Indicator On = 11-17% or 4.3 gallons (2.4V or 208-218 ohms)

Low Fuel Indicator Off = 14-25% or 5 gallons (2.3V or 195-206 ohms)

On a normal system, when the light comes on you should be able to take on 21-22 gallons of fuel. In normal city driving a Denali like yours should average about 14 MPG and go about 300 miles until the light comes on. Another 100 miles or so for an all highway mileage trip.

In my older GM cars, they would stay on full forever and then swing over towards empty. On my 2009, the needle moves off of full quickly and once down near empty stays at 11% for 50-100 or more miles. My tank is 31.5 gallons and it has never taken more than 29.76 gallons and the average fill once the light comes on is 26 gallons.

So how far are you travelling between refueling events? Have you run it down to the light and then filled it up shortly after? If so, how much fuel did she take on?

DCoop · October 14, 2020

Thankyou for the info. I have never let the light come on as I'm afraid of burning out the fuel pump. My gas mileage sucks as I am usually pulling my car trailer with my antique truck on it to car shows. When not towing, a 40 mile trip is about 3 gallons. With the 6.2 L engine I don't expect much better, but is great for towing.

DCoop · October 14, 2020

to Senior Enthusiast. I think your idea will be the easiest and cheapest to start with. It's off to the shop for a complete scan and set up. DCoop..

swathdiver · October 14, 2020

1 hour ago, DCoop said:

Thankyou for the info. I have never let the light come on as I'm afraid of burning out the fuel pump. My gas mileage sucks as I am usually pulling my car trailer with my antique truck on it to car shows. When not towing, a 40 mile trip is about 3 gallons. With the 6.2 L engine I don't expect much better, but is great for towing.

You're not going to hurt your fuel pump by refueling when the light comes on, there is still plenty of fuel on board for that. At 13 MPG you can still easily attain 275 miles per tank and if towing, you're getting what, about 8-9 MPGs? That's about 175 miles per tank.

CamGTP · October 14, 2020

Drive slower and the 6.2 can easily do 19-20mpg on the freeway. If you get 13-14mpg when not towing maybe you have the heaviest foot and go about 90mph everywhere.