2003 Yukon won’t accelerate past 3,000rpm and chokes/sputters

[Rshann5355]

when the tank wont fill right, or clicks off like its full repeatedly as you fill it, thats the charcoal canister. its pellets broke free and are clogging up a vent line. or the level sender is broken and wont read full anymore or shows empty when its got a 1/4 tank.

if the cel flashes the cats could be clogged up, or it needs a tune up bad. like last year bad.

id still check the f/p like others stated. most parts stores do a free rental. you leave a deposit on the tool and they refund it back when you drop it back off. free test first always before just throwing parts at it. also scan it when at the parts store, the cel light may be burnt out so you wont know if theres codes or not with out scanning it. key to run engine off shows all the dummy lights. make sure the cel is lit up. aka then you know its working. id still scan it running after it acts up. if its setting a pending code it will clear when you turn off the engine.

In regards to a tune up, the truck does have brand new ignition wires and NGK spark plugs that were done about 2,000 miles ago. I don’t believe the ignition coils were replaced, but from my understanding the issue I’m having is not related to ignition coil failure.

 

[RAMurphy]

Welcome to the forum. You are already receiving sage advice from the members of this awesome forum.

 

[OR VietVet]

Thank you all so much, sorry it took so long to get back to you all as I’ve been at work. A few more details, sorry I’m leaving things out, but the truck will drive down the road. I can take it to work and back, the issue just gets worse the lower it gets on fuel. The truck had all the seals redone (including the rear main) when it was in the shop, and I do have a scanner that can read it. I have to replace a fuse as my cigarette lighter and OBD2 port are not working, but I’m hoping it’s that easy of a fix. I’ll be replacing the fuel filter on Saturday to see if this helps the issue as well. Picture of truck currently is attached. View attachment 385470

You say, "The issue gets worse, the lower you get on fuel". I am confused now. Are you saying the issue is always there and just gets worse enough as the fuel gets lower for you to have a concern? Or, are you saying that there is NO issue till the fuel gets to a certain gauge level? Then I would want to know the level that it happens at and then I would also likely point to a pump problem but I still would like to know the fuel pressure from start up to driving it, especially if the fuel level gets low enough for you to have a concern. At this point, I would not personally point at a filter as the problem but knowing @rockola1971's diagnostic strength's, I would not rule it out but would tell you that you MUST replace it with any new pump you might install and use only a quality pump and filter from GM or Delphi. Your whole problem, smell and all, could be exposed by dropping the tank.
Add on info vvvvv
But, and this is a BIG but, if the filter has been on there too long and worn out the fuel pump trying to push fuel thru a wall in the filter, I am thinking it may be easier if the fuel tank is full of fuel. Hell, I don't know. I wish I could experience the problem at the time it is doing it, DON'T WE ALL!

 

[rockola1971]

You say, "The issue gets worse, the lower you get on fuel". I am confused now. Are you saying the issue is always there and just gets worse enough as the fuel gets lower for you to have a concern? Or, are you saying that there is NO issue till the fuel gets to a certain gauge level? Then I would want to know the level that it happens at and then I would also likely point to a pump problem but I still would like to know the fuel pressure from start up to driving it, especially if the fuel level gets low enough for you to have a concern. At this point, I would not personally point at a filter as the problem but knowing @rockola1971's diagnostic strength's, I would not rule it out but would tell you that you MUST replace it with any new pump you might install and use only a quality pump and filter from GM or Delphi. Your whole problem, smell and all, could be exposed by dropping the tank.
Add on info vvvvv
But, and this is a BIG but, if the filter has been on there too long and worn out the fuel pump trying to push fuel thru a wall in the filter, I am thinking it may be easier if the fuel tank is full of fuel. Hell, I don't know. I wish I could experience the problem at the time it is doing it, DON'T WE ALL!

Im thinking the mudtruck has a bad oring on the top of the tank for the module. Mud is getting into the tank and the small stuff is getting past the fuel pump sock and into the fuel filter on the frame rail. Very common to idle correctly but as engine speed increases (and so does fuel consumption), the fuel filter can only flow so much before it starts to choke the engine because it is plugging up. Then when the fuel flow in the filter drops off the dirt falls away from the filter element and idle is ok. Could also just be that the fuel filter hasnt been changed in many years and its time.

 

[Rshann5355]

Im thinking the mudtruck has a bad oring on the top of the tank for the module. Mud is getting into the tank and the small stuff is getting past the fuel pump sock and into the fuel filter on the frame rail. Very common to idle correctly but as engine speed increases (and so does fuel consumption), the fuel filter can only flow so much before it starts to choke the engine because it is plugging up. Then when the fuel flow in the filter drops off the dirt falls away from the filter element and idle is ok. Could also just be that the fuel filter hasnt been changed in many years and its time.

I was having this same train of thought, I don’t want to immediately jump to the fuel pump (even though they go out left and right in GM vehicles). I’m going in the morning for the fuel pressure test, then taking it over to a family members house to drop the tank and see what I’m looking at as far as mud build up. I already have to replace the brake master cylinder while I’m there so I’ll be inspecting most of the lines to and from the rear of the truck.

 

[OR VietVet]

Well, I changed my fuel pump while life was still LEFT in it so I guess my next fuel pump change is RIGHT around the corner..

I was having this same train of thought, I don’t want to immediately jump to the fuel pump (even though they go out left and right in GM vehicles). I’m going in the morning for the fuel pressure test, then taking it over to a family members house to drop the tank and see what I’m looking at as far as mud build up. I already have to replace the brake master cylinder while I’m there so I’ll be inspecting most of the lines to and from the rear of the truck.

 

[Rshann5355]

Alright, just got the fuel pressure test done and it’s holding 50PSI at idle, but once it’s turned off it leaks down pretty darn quickly. Shop said should expect a leaking injector possibly, but the truck has been starting almost instantly and idling without issue.

 

[Fless]

Is this a Flex Fuel engine or not (what's the 8th character of the VIN)? Pressure specs are different for Flex vs. non-Flex.

Standard fuel pressure test is with KOEO (key on, engine off); what does the fuel pressure read when initially turning the key to "run" without starting? Then when you turn the key off, how much pressure is lost over a short amount of time? PSI loss value and elapsed time will be helpful.

Idle doesn't seem to be an issue, does it? What does the fuel pressure do when you increase the rpms or load down the engine (in drive, with the brakes applied, and some gas pedal pressure)?

It sounds like a fuel delivery issue, caused by defective fuel pump, plugged filter, or defective fuel pressure regulator.

 

[Rshann5355]

Is this a Flex Fuel engine or not (what's the 8th character of the VIN)? Pressure specs are different for Flex vs. non-Flex.

Standard fuel pressure test is with KOEO (key on, engine off); what does the fuel pressure read when initially turning the key to "run" without starting? Then when you turn the key off, how much pressure is lost over a short amount of time? PSI loss value and elapsed time will be helpful.

Idle doesn't seem to be an issue, does it? What does the fuel pressure do when you increase the rpms or load down the engine (in drive, with the brakes applied, and some gas pedal pressure)?

It sounds like a fuel delivery issue, caused by defective fuel pump, plugged filter, or defective fuel pressure regulator.

Fuel pressure regulator was recently replaced but I discovered today that they did not replace (or attach at all) the vacuum line for the regulator, so I replaced that. I also installed a new fuel filter and that definitely helped the issue by a decent margin, but you still can't get down in it all the way without a sputter. I'll be replacing the fuel pump next along with the sending unit.

 

[rockola1971]

Fuel pressure regulator was recently replaced but I discovered today that they did not replace (or attach at all) the vacuum line for the regulator, so I replaced that. I also installed a new fuel filter and that definitely helped the issue by a decent margin, but you still can't get down in it all the way without a sputter. I'll be replacing the fuel pump next along with the sending unit.

Yeah 50 Psi and all the bleed off aint gonna cut it. Id expect atleast 55-60 PSI with almost no leak down.