Suburban dilemma
Last year I bought an 08 suburban 2500 with 51,000 miles. Body in excellent condition. I planned on using this to tow my trailer and be an everyday driver for my wife for many years to come. It ran an...
Forum Discussion
Not sure about the 2008, but on the 01-06 with the 8.1L, you got 2 fuel tanks. The main tank is on the left side inside the frame rail, basically under the driver's seat, and the second is in the rear, under the cargo floor, above the spare tire holder. I'm not 100% certain how this system operates, but I can tell you what I know from taking it all apart in 2013 to replace the brake lines and fuel lines.
The fuel filler neck on the rear fender flows gas into the rear tank, and the rear tank is also connected to the main tank with a large gravity feed tube. Despite this, each tank has it's own electric fuel pump with sending gauge.
The main tank operates as expected, there are fuel, return, and evap lines connected and the pump runs whenever the ignition is on. The rear tank is configured similarly, with fuel and evap lines connected to the main tank. The pump in the rear tank doesn't run continuously, but is cycled by the PCM.
NOTE: The service manual only states the above, it doesn't say what conditions the PCM uses to turn the fuel pump on/off, it only states that you can test activate the pump with a scan tool.
Each pump sends its fuel level readings to the PCM which then uses an algorithm to combine the readings and determine where to display the dash fuel gauge.
So I'm not sure why there is a pump in the rear tank to pump fuel into the front tank when the rear tank sits higher than the front tank and there is a large gravity feed from one to the other. I've not heard of the rear pump causing a stall or no-start condition, but that doesn't mean it's not possible.
Servicable life on GM fuel pumps has proven to be about 100k miles....if you were inclined, you might consider changing both fuel pumps, if nothing else but to rule them out as a suspect.
The fuel filler neck on the rear fender flows gas into the rear tank, and the rear tank is also connected to the main tank with a large gravity feed tube. Despite this, each tank has it's own electric fuel pump with sending gauge.
The main tank operates as expected, there are fuel, return, and evap lines connected and the pump runs whenever the ignition is on. The rear tank is configured similarly, with fuel and evap lines connected to the main tank. The pump in the rear tank doesn't run continuously, but is cycled by the PCM.
NOTE: The service manual only states the above, it doesn't say what conditions the PCM uses to turn the fuel pump on/off, it only states that you can test activate the pump with a scan tool.
Each pump sends its fuel level readings to the PCM which then uses an algorithm to combine the readings and determine where to display the dash fuel gauge.
So I'm not sure why there is a pump in the rear tank to pump fuel into the front tank when the rear tank sits higher than the front tank and there is a large gravity feed from one to the other. I've not heard of the rear pump causing a stall or no-start condition, but that doesn't mean it's not possible.
Servicable life on GM fuel pumps has proven to be about 100k miles....if you were inclined, you might consider changing both fuel pumps, if nothing else but to rule them out as a suspect.
