07 Yukon XL 2500 Hard Stating

[ljs05]

Truck started hard at first only after fueling. And had a little bit of a rough idle. I have replaced the purge valve and the fuel injectors. Now seems to start hard all the time. Also when it starts it seems to barely catch at first and takes a minute for the RPMs to rise. Idles at about 600 no matter in drive or park. Tested pump pressure and it goes up to 55 as soon as key is turned on. Will go to about 60 when running. Will very slowly go down after engine is turned off. And I mean VERY slowly, less than the 5lb in 1 minute the manual states.
What could be problem??????????

 

[OR VietVet]

Need mileage and age of the other tune related components. Many options as to what the problem is. MAP, MAF, vacuum leak, dirty throttle plate....etc.


We recommend that you put all your rig(s) info in your signature so we all don’t have to guess at year, make, model, engine size, trans, rear axle locker…….etc. While you may have posted pertinent info in your first post, you may forget to do it again and the info is needed by us anyway. Makes it way easier on all members that attempt to help, to have that info right up front. It is also recommended that you take a pic of your RPO codes, on the inside cover of the glove box, and post that image in your signature. All this info will greatly help those that will try to help with a problem.


If there is any other info, like upgrades, mods or recent mechanical/maintenance work done, that would be helpful in any post as well. Too many times a question is asked by the poster and after about 10 responses we find out that the poster has done recent work to attempt to fix the problem or work that was done that SEEMS not related to the problem.

 

[Meccanoble]

I was hoping you just had bad gas but I'm in for feedback. Hope it works out.

 

[swathdiver]

Truck started hard at first only after fueling. And had a little bit of a rough idle. I have replaced the purge valve and the fuel injectors. Now seems to start hard all the time. Also when it starts it seems to barely catch at first and takes a minute for the RPMs to rise. Idles at about 600 no matter in drive or park. Tested pump pressure and it goes up to 55 as soon as key is turned on. Will go to about 60 when running. Will very slowly go down after engine is turned off. And I mean VERY slowly, less than the 5lb in 1 minute the manual states.
What could be problem??????????

Are you viewing the pressure with a mechanical gauge or scan tool?

 

[ljs05]

Are you viewing the pressure with a mechanical gauge or scan tool?

Mechanical Gauge

 

[swathdiver]

Mechanical Gauge

Can you view it while driving? A good scan tool might be able to show commanded and actual fuel pressures and it Long Term Trim. However, on a fellow member's '07 Tahoe, I could not find this information with my Tech-2, even calling his truck something else, like mine. Your menu may be different. The point of this is to be able to verify pump performance.