I have a 2007 Suburban (1500 2WD) and it died mid flight two days ago while my wife was driving it home. Luckily she wasn't too far from the house and I was able to start it up and and coast it home as it continued to die after about 5 seconds. I'm needing help trying to find out what the problem is. Battery is fully charged, it has a new alternator, full tank of gas. The suburban will always start but then dies about 5 to 10 seconds after it starts, so it's getting enough gas to start but I"m not sure if the the fuel pressure isn't maintained after that. I tried opening the gas cap to see if that made a difference and it did, the car continues to run with the gas cap off, although at a low RPM of about 600. As soon as the gas cap is put back on the car will die. While the gas cap was off it threw the check engine light and codes P0172 and P0175 came on. I'm not sure if this was triggered due to the gas cap off and creating a rich oxygen scenario. Also for the last year the car has had a hard time starting right after it is fueled up, but always starts the second time trying and while putting foot on the gas pedal. Thanks for your help and input, I appreciate it!

 

The pressure from the pump PSI was at 60 before starting. The pump seems to be working fine and not the issue.

 

Maybe a vacuum hose knocked off near or around the throttle body? Dirty MAF sensor maybe or throttle body? Have you pulled the air cleaner lately to see what it looks like in there?

 

I haven't cleaned it in a few years, I will check it out. Also the check engine light finally came on after it was accidentally reset and P0172 and P0175 are coming up. Any thoughts?

 

UPDATE
* Cleaned MAF and put new air filter in. Very dirty air filter and glad I checked that and cleaned everything out.
* Cleaned Throttle Body. A little bit of carbon build up but not a lot.

Symptoms continue after the cleaning. Car starts every-time and dies after about 5 seconds
* Fuel Pressure is at about 60 PSI before starting and while running, drops quickly when car dies
* Battery is good at 14 or higher
* Car has been flooding for several months now every-time I fill it up but usually starts on second try after pressing the gas pedal several times.

Thanks again for any help or guidance.

 

the two codes are for running rich. flooding after a fuel filling event can be due to a stuck open purge solenoid valve. find the purge valve...it will have a hose running to the throttle body...remove the hose and try to blow thru the valve...if you can...replace the valve.

Is the vehicle flex fuel compatible?

 

Thanks for the reply. I replaced this about a year ago, I guess it may have gone bad again and check by blowing through it. Yes, its a 5.3L Vortec with Flex Fuel (been putting E85 in it for years). The puzzling part to me is why the car will run with the gas cap off and dies once its put back on? I tried a new gas cap also but that didn't fix the problem.

 

if you have any cai intake installed ; remove it and go back to the factory unit.
have someone with a scan tool reset the flex fuel sensor and fuel trim settings...see what percent its reading...if its out of whack with the fuel you are putting in the vehicle it will skew the fuel trim adjustments.