Engine Struggling to Accelerate at WoT

[Schurkey]

fuel pressure read good at the throttle body

Under load? Or just at idle?

22 and 25 PSI on the fuel seems abit on the high side.

Is the gauge accurate? How do you know?

 

[CrashDriver]

Under load? Or just at idle?


Is the gauge accurate? How do you know?

Driving down the road it was reading 25 psi, I don't recall but I'm pretty sure if I goosed it a little it would dip but so would the engine; I think I may have made some kind of choke point in my testing setup because I don't have a T-junction for the tester and don't have time to get one so I kind of jerry rigged a setup:

You must be registered for see images attach

kind of a crappy photo from my phone but I marked it for some clarity. That first bend isn't as tight as it looks from that angle but that length and the more narrow t-section at the tester may have bottlenecked the fuel some, I dunno. The gauge itself is accurate, yes.
I'm thinking tomorrow I may test it again but shorten the line as much as I can and see if I can scrounge up some wider fittings

 

[movietvet]

Driving down the road it was reading 25 psi, I don't recall but I'm pretty sure if I goosed it a little it would dip but so would the engine; I think I may have made some kind of choke point in my testing setup because I don't have a T-junction for the tester and don't have time to get one so I kind of jerry rigged a setup:

You must be registered for see images attach

kind of a crappy photo from my phone but I marked it for some clarity. That first bend isn't as tight as it looks from that angle but that length and the more narrow t-section at the tester may have bottlenecked the fuel some, I dunno. The gauge itself is accurate, yes.
I'm thinking tomorrow I may test it again but shorten the line as much as I can and see if I can scrounge up some wider fittings

I am really glad you are not giving up on this problem. Others may have caved by now. The problem is there and wants to be found. You are getting better at the thought processes with the suggestions. There was a member here that said something in another thread that was several posts in and it stuck with me. I am gonna paraphrase: These trucks are designed to let the owner work on them and not just hand the keys over to a shop every time there is a problem. "You are becoming ONE with your truck". Not trying to be a smart ass. Just letting you know that it is commendable that you are still soldiering on. I gotta say, I do have more fun working on my girl's 1990 K2500 than I do working on my GMT800 2005 Tahoe. Even though her truck is 34 years old, there is still an abundance of quality parts and quality info to keep it going. Efff those communist turds that want to tell me what I should drive and what I can drive.

 

[CrashDriver]

I am really glad you are not giving up on this problem. Others may have caved by now. The problem is there and wants to be found. You are getting better at the thought processes with the suggestions. There was a member here that said something in another thread that was several posts in and it stuck with me. I am gonna paraphrase: These trucks are designed to let the owner work on them and not just hand the keys over to a shop every time there is a problem. "You are becoming ONE with your truck". Not trying to be a smart ass. Just letting you know that it is commendable that you are still soldiering on. I gotta say, I do have more fun working on my girl's 1990 K2500 than I do working on my GMT800 2005 Tahoe. Even though her truck is 34 years old, there is still an abundance of quality parts and quality info to keep it going. Efff those communist turds that want to tell me what I should drive and what I can drive.

Thanks, lol - I don't have a whole lot of experience under my belt yet but I've been working on learning everything I can about working on my own vehicles so I don't have to take them to a mechanic for pretty much anything besides a tire alignment; it's very frustrating sometimes but the taste of victory is oh so sweet...

 

[movietvet]

Thanks, lol - I don't have a whole lot of experience under my belt yet but I've been working on learning everything I can about working on my own vehicles so I don't have to take them to a mechanic for pretty much anything besides a tire alignment; it's very frustrating sometimes but the taste of victory is oh so sweet...

Yeah, when you accomplish something or finally fix the stubborn problem, that is one for the memory banks.

 

[CrashDriver]

Well, another update; driving to and from work today I noticed the truck is running very smoothly, it doesn't chug or feel crappy anymore. This is after I replaced the IAC valve and the ICM, so one or both helped with that problem.
The only problem left is it still pops and it lacks power on hills and acceleration, so this evening I'm pulling apart my fuel regulator.

 

[CrashDriver]

Still not fixed, guess I'll have to run it to georgia like this... time's up. Figure it out when either the engine goes or I make it back, lol

 

[movietvet]

Was clogged cat(s) or muffler ever checked?

 

[CrashDriver]

Well I made it back from Georgia all right, truck never had any problems at all besides that it still pops. but over that roughly 2400 mile trip I got a good feel for how it's affecting the truck mechanically - it really struggles to gain acceleration on hills and just general acceleration past the low end it struggles with.
Pretty much the only electrical thing I haven't replaced on top of the engine is the MAP sensor, but I figure it's got to be some sort of stuck valve or something.
When it's cold the first time you go up a hill and put strain on the engine even going slow it'll pop and struggle for a few seconds but then it'll run fine the entire time after outside of hard acceleration.

 

[CrashDriver]

New update: I did a dry crank compression test on all the cylinders and they're all right at 150 psi except for two which are 155 and 160ish, but that doesn't seem like a problem to me.

While I was doing that I accidentally shredded one of my plug wires, so I figured since they're the only older part of the ignition system I may as well replace the whole lot.
When the wire was exposed, even when I wrapped it the truck lost even more power and popped and shuddered worse than before.
Ironically, when I replaced the wires the truck doesn't run any better, so it would seem that whatever worsened was just coincidental with my wire issue.

Everyone with experience that I told about my basic engine troubles said it sounded like timing, so I figured screw it, I'll try timing it by ear (it was right on 0 degrees with the advance disconnected). I set it to about 10 degrees, but running that only seems to make the engine run worse.

So back to 0 degrees again and the drawing board I guess... I don't even know what to look for at this point.