Is It Really Empty?

2005LT · July 16, 2008

Hello everyone,

I have a question regarding my 2005 silverado ext cab standard box. I have searched for this but none of the topics that came up matched this issue.

My owners manual says my fuel tank is 26.0 gal = 98 L. The DIC indicates that I have burned out 71 L but that is usually out by ~ 5% when I fill up at the pump. In this case, I would expect to put in 74 or 75 L = 19.8 gal.

Thing is, my fuel gauge is now barely above the "E" mark and the low fuel light has begun to come on. I only drive about 5 or 6 miles at a time so the low fuel light may come on one trip (like yesterday afternoon) and not on another (this morning). So I assume the fuel level is right at the point of triggering the low fuel sensor. What I don't get is that there should be ~ 23-25 L (6 gal) left so why is the needle down to the red "E" mark already? I currently have 580km = 360 miles on the tank.

Any ideas? I know it's a very minor issue but I am curious to see what happens if I keep driving it .

lsorah0001 · July 16, 2008

I've always been told, that when the light comes on, you have ~30 miles until you are completely out. Never tested this, though.

silverad03 · July 16, 2008

I couldn't tell you exactly why your fuel gauge is off, other than to say:

1. Generally, the gauges in these trucks are not 100.00% accurate - gauge readings are more like "pretty close".

2. Just a guess here, but I assume that part of the fuel pump assembly contains the fuel gauge float. If this is the case, your fuel gauge would always be a little pessimistic about the remaining fuel level because the fuel pump assembly mounts from the top down (likely leaving a gap between the bottom of the unit and the bottom of the tank).

3. The fuel pickup probably isn't slurping off the very bottom of the tank either, which could cause you to run out of gas sooner than you anticipate if you're driving on E.

Also, as a word of caution, I've heard from various sources that running your truck on empty very often can be bad on your fuel pump because it relies upon the fuel in the tank to dissipate heat and keep it cool. I can't confirm this as fact, though. Someone else will have to chime in and correct any misinformation I've given to you

SoCalChris · July 16, 2008

Also, as a word of caution, I've heard from various sources that running your truck on empty very often can be bad on your fuel pump because it relies upon the fuel in the tank to dissipate heat and keep it cool. I can't confirm this as fact, though. Someone else will have to chime in and correct any misinformation I've given to you

I've heard 2 different dealers mention this. The first one mentioned it while I was getting the fuel pump replaced in our '99 Safari. I overheard the second dealer mention it to another guy who was in getting his fuel pump replaced.

It's also bad because any loose gunk that accumulates on the bottom of the tank can be sucked in, and clog your filter.

As for the amount of fuel left when the low fuel warning comes on, the one time I let my tank get low enough to complain I still had about 7 gallons in it. My truck has the 34 gallon tank though.

D&SYukonDenali · July 16, 2008

Over the last 200 gal of fuel (10 fill-ups), my fuel gauge was been ~2% accuracy if I assume a 3 gal reserve ( reserve not registering on the fuel gauge). The other thing I have noticed, the more remote start is used, the bigger the difference will be between the DIC and fuel pump amount for fuel consumed.

2005LT · July 17, 2008

Thanks for the replies. I have heard about the low fuel causing fuel pumps to grenade due to cooling. I never usually let it run this low but I was curious since something didn't seem right. My 1995 6.5 diesel was empty when the needle showed empty. Granted it was out a bit when reading in the mid-range (showing 1/2 tank left when only 1/3 actually remaining). I guess the "reserve" on this one is quite a bit higher than on my old truck.

D&SYukonDenali · July 17, 2008

I would guess that GM increased the size of the reserve that does not read on the fuel gauge to decrease roadside assistance costs.

2004GMC1500CC · July 17, 2008

Also, as a word of caution, I've heard from various sources that running your truck on empty very often can be bad on your fuel pump because it relies upon the fuel in the tank to dissipate heat and keep it cool. I can't confirm this as fact, though. Someone else will have to chime in and correct any misinformation I've given to you

I've heard 2 different dealers mention this. The first one mentioned it while I was getting the fuel pump replaced in our '99 Safari. I overheard the second dealer mention it to another guy who was in getting his fuel pump replaced.

It's also bad because any loose gunk that accumulates on the bottom of the tank can be sucked in, and clog your filter.

As for the amount of fuel left when the low fuel warning comes on, the one time I let my tank get low enough to complain I still had about 7 gallons in it. My truck has the 34 gallon tank though.

Umm, aren't the fuel pick up's at the bottom of the tank already?

2005LT · July 17, 2008

That's a really good point Dan. The though crossed my mind as I figured it would get people to stop and fill up sooner. Other than that, I'm pretty happy with the gauge in this truck. It moves very consistently and evenly as the tank runs out which is unlike past GMs we've owned.

SoCalChris · July 17, 2008

Also, as a word of caution, I've heard from various sources that running your truck on empty very often can be bad on your fuel pump because it relies upon the fuel in the tank to dissipate heat and keep it cool. I can't confirm this as fact, though. Someone else will have to chime in and correct any misinformation I've given to you

I've heard 2 different dealers mention this. The first one mentioned it while I was getting the fuel pump replaced in our '99 Safari. I overheard the second dealer mention it to another guy who was in getting his fuel pump replaced.

It's also bad because any loose gunk that accumulates on the bottom of the tank can be sucked in, and clog your filter.

As for the amount of fuel left when the low fuel warning comes on, the one time I let my tank get low enough to complain I still had about 7 gallons in it. My truck has the 34 gallon tank though.

Umm, aren't the fuel pick up's at the bottom of the tank already?

Good point... Never mind me.