Yukon Xl 2500 Thinks It Has Dual Fuel Tanks

yukonpullin · August 13, 2008

My 2003 Yukon XL 2500 (6.0L 4WD) has always had a strange issue with the fuel gauge. If I run the single tank down to near empty, then fill it, on the next start, sometimes the gauge will read empty, or only partly full. Then on the next start after that all is well. While under warranty, I had the tank sender replaced. No luck there, and that's where it's been for years now. The dealer never could fix it, they're not what I'd normally call "Rocket Scientists".

So, I received this letter from GM telling me about problems with the instrument cluster. It seems similar to what I'm seeing so I take it down there. The shop foreman and I hook up a Tech2 to the diagnostic port to get some information so that a new instrument cluster can be ordered and lo and behold there's a trouble-code history that didn't set off the check-engine light. It's DTC 1172, which on this vehicle means that the fuel transfer pump failed to show sufficient flow. Apparently, on startup, on dual tank vehicles, the fuel transfer pump engages for a short time, and the system looks at the fuel level between the two tanks to see it change. If it doesn't change, then it throws this error, and sometimes forces the fuel gauge to empty! Bingo, problem found. Except for one thing. There isn't a second tank on this particular vehicle, or a transfer pump for that matter.

Has anyone else seen this? More importantly, how did you fix it? I'm thinking a reflash of the PCM should get it done as I'm still running 2003 code, but maybe not. Any ideas?

Mark

bossier62guy · August 13, 2008

My 2003 Yukon XL 2500 (6.0L 4WD) has always had a strange issue with the fuel gauge. If I run the single tank down to near empty, then fill it, on the next start, sometimes the gauge will read empty, or only partly full. Then on the next start after that all is well. While under warranty, I had the tank sender replaced. No luck there, and that's where it's been for years now. The dealer never could fix it, they're not what I'd normally call "Rocket Scientists".

So, I received this letter from GM telling me about problems with the instrument cluster. It seems similar to what I'm seeing so I take it down there. The shop foreman and I hook up a Tech2 to the diagnostic port to get some information so that a new instrument cluster can be ordered and lo and behold there's a trouble-code history that didn't set off the check-engine light. It's DTC 1172, which on this vehicle means that the fuel transfer pump failed to show sufficient flow. Apparently, on startup, on dual tank vehicles, the fuel transfer pump engages for a short time, and the system looks at the fuel level between the two tanks to see it change. If it doesn't change, then it throws this error, and sometimes forces the fuel gauge to empty! Bingo, problem found. Except for one thing. There isn't a second tank on this particular vehicle, or a transfer pump for that matter.

Has anyone else seen this? More importantly, how did you fix it? I'm thinking a reflash of the PCM should get it done as I'm still running 2003 code, but maybe not. Any ideas?

Mark

Here's some interesting reading for you Mark. I realize it does not say it affects the Yukon but it sounds like your problem nonetheless. I'm surprised that the GM dealer didn't come across anything and offer to fix your vehicle even if it is out of warranty.

http://www.gmupfitter.com/publicat/bull/bull72.pdf