2005 Yukon. Engine starts chugging and then dies at stop lights or low rpms.

[rcecarbldr]

So now riddle me this GM techs. I'm driving to Rural King (10 mile drive) and at every stop light now the motor starts chugging and eventually dies. But I can put it in park and it will fire right back up. Put in gear and it drives along just fine as long as I'm the throttle and going faster than like 30mph. And in fact if I mash the pedal it's fine but next stop light, chug, chug dead.
It did that to me at every stop I hit between there and my shop, and back.
I managed to stop at my buddy's shop, Jeff's Tuning and Performance, LLC where he put a fuel pressure gauge on it and when I first turned the key just on it had roughly 48psi. Then Istarted it and just over 55psi. But then I set the parking brake, put it in gear and it suddenly started chugging again and the fuel pressure dropped to like 8psi and stayed there till it died again. WTF?? Runs fine ******* the throttle but dies at low rpm or idle.
I does it with the AC on or off. In park or in gear. Everyone tells me the fuel pump but why would it run fine when I'm accelerating hard? Some say is the fuel pressure regulator, others I have a ground issue. Also it did this once before several months ago and after I disconnected the battery, let the ECU reset and reconnected the battery it was fine for months but now it's back to doing it again but worse than ever. Yes I was told the ECU has nothing to do with the fuel pump. Thoughts?

 

[rockola1971]

Pull the vac line to the fuel pressure regulator, Is the line inside wet with fuel? Does vehicle run fine without vac line attached (but plugged) FPR? If not then your 8Psi fuel pressure told you what was wrong. Bad fuel pump.

 

[rcecarbldr]

Pull the vac line to the fuel pressure regulator, Is the line inside wet with fuel? Does vehicle run fine without vac line attached (but plugged) FPR? If not then your 8Psi fuel pressure told you what was wrong. Bad fuel pump.

Pull the vac line to the fuel pressure regulator, Is the line inside wet with fuel? Does vehicle run fine without vac line attached (but plugged) FPR? If not then your 8Psi fuel pressure told you what was wrong. Bad fuel pump.

This year has the regulator in the fuel tank with the pump. After erasing the ECmM I drove it nearly 2 hours over to Daytona and back to Ocala without a hiccup, till I went to pull it into my shop then suddenly it chugs, sputters and dies. WTF? I'm thinking a bad ECM because no codes.

 

[Fless]

What's the "ECmM?" And what does it mean to erase it?

What engine? Flex fuel or Gas? How many miles on the current fuel pump?

Just for grins I'd pull the ECM connectors and look for pin fitment and connection quality. But it sounds like the fuel pump assy.

Here's a link to the diagnostic procedure for the 5.3L engine, but use the links at the top of the browser page to navigate to your specific engine. Note the difference between the Gas and the FF pump pressure specs.

Fuel System Diagnosis — 2005 GMC Yukon/Denali 2WD V8-5.3L VIN T Service Manual | Operation CHARM

Detailed repair manual for the 2005 GMC Yukon/Denali 2WD V8-5.3L VIN T.

charm.li