I have a 04 silverado 5.3 with sts turbo gt35, 43lb inj. 255 walbro pump, Nelson tune, and can't get past 5,000 rpm in first and 4,500 in second. Sounds like it is running out of fuel. Spent 6hrs. at Xtreme motorsports yesterday and they checked everything they could think of and couldnt find the problem. Although all the header tubes on the drivers side were around the same temp. 250degrees, the tubes on the pass side varied. The two back one's were around 350 degrees and the two front were 165degrees indicating fat in the front and lean in the rear? Swapped the two injectors from the rear to the front and no differance. Any ideas what the problem is. Thanks

 

did they do any logs? That may help find the problem. Is it going lean or do you think it is going lean at those points?

 

They did the laptop thing and said that fuel tables looked good?

 

Did they hook it up to a wideband to show where and how drastically it was going lean?
Im sure someone more knowledgable than myself will chime in here. There are alot of sharp guys on here.

 

So what is your max boost at? Do you have an upgraded fuel pump as well?

 

Where are you located?

 

Whats your boost? My '04 was going lean at 5psi on stock injectors.

 

I'm in the try-state AZ, Laughlin Nev. and Cal.

 

Boost is at 6lbs. and using Walbro 255 pump (second new one) with 43lb injectors.

 

any reason why this is your 2nd fuel pump...or just a bad 1st pump...