Hey guys, my mothers 95 K1500 w/ 5.0L 305ci Chevy truck with TBI injection, has been on the fritz lately, Ive posted of some chevy forums but they have been no help or no one has even replied in 4 days. But anyways here is the issue...
Truck will start, idle most of the time. I can rev the **** out of it in park or neutral with no problems at all. The big issue comes once its in gear, once you put it in gear and press the gas pedal, the truck acts like it has no power, its kind of hard to explain, but if you press on the pedal to take a fast start, the engine bogs down and just acts like it has no power and feels like its going to die. If you "flutter" the pedal you can keep it running, it will barely climb the drive way. Here are some things ive done, checked, or looked at.

1) Fuel Pressure: Checked and is fine.
2) Vacuum Leaks: Checked, found the PCV valve hose that goes to the TBI was broke. Fixed no change in the problem.
3) Coil: Checked spark, was getting a yellow spark, replaced the coil, got a blue spark and solved the hard start issue i was it was having. Still no change in the main issue.
4) Plugs,wires, cap and rotor: Were replace about 3 months ago, My little brother used Bosch Platinums, I rechecked the gaps and all were ok, but i went ahead and replaced with standards autolight plugs. Still no change.
5) IAC: Checked and it is actuating
6) TPS: Checked with an OHMS meter, Throttle closed i got 1.118 as the throttle is increased so does the resistance until i get to WOT, then it drops back to arounf 1.118 or so. Should it keep climbing even at WOT?
7) EGR valve: Took it off cleaned the openings, did a vacuum check and found it leaked down after vacuum is applied. I tried disconnecting the Vacuum line and plugging it, truck will not run with out the vacuum line hooked up. I Think this ultimately may be my problem, just waiting on the part to arrive from Rock Auto.
8) TBI unit: Upon advice from the local mechanic, he drove it said it sounded and felt like bad injectors, I bought a TBI rebuild Kit and new Injectors. Rebuilt the TBI, reinstalled and still have the same issue.

I understand this isnt a dodge, but you guys do a hell of alot better at diagnosing then ive seen in other forums. Thanks again for any other suggestions.

 

Put a dodge motor in it and it will fire right up

Does it bog down the same way trying to accelerate in reverse? If it does, at least you know it is the motor and nothing else.

Try unplugging the TPS and driving.

 

I'm assuming from everything you have checked/replaced, that you have already checked your transmission fluid? Short of that, I wouldn't be surprised if your problem lies inside the transmission itself. If it runs fine while in park or neutral, that leads me to believe the problem isn't in the motor. 4x4 or no? is it is a 4x4, look into the transfer case, they were never built "like a rock", but then again, even rocks break..

Another thing, have you checked the computer for codes? just because there isn't a check engine light, doesn't mean there isn't a code stored

 

I assume it is an automatic given the neutral, but can you still rev it while it is in gear? Just lack of "go"? Check fluid, check TV cable. Probably the transmission given the info.

 

How does the engine run at idle? Any misses? Sounds like (to me) your firing order is wrong. At idle the engine will run on 4 or 6 cylinders, but once you put a load on it 4 or 6 cylinders isn't enough to keep it running. When I saw that you replaced the wires, makes me think you didn't get the firing order right.

A.J.

 

A 1995 should be a 4L60E so no kick down or TV cables. It's a K1500 so it's 4wd, my first guess would be along the lines of what Siggie said, could be behind the motor.

Make sure the exhaust (read: the cat) isn't plugged anywhere either. The old 4.3 S15 in my sig had similar problems because of it until it blew the guts out the tail pipe.

 

Transmission seems to be working fine, it shifts just fine when i can keep the engine running in gear, (Confusing huh!) it was replaced with a rebuilt one less then 3 months ago. I checked for codes, no codes where stored.
Yes automatic, fluids are fine, cables are fine, No, the engine itself bogs down, it revs ok out of gear, even in gear with my foot of the brake, the engine wants to die.
No misses at idle, purrs like a kitten, firing order is correct, went over it several times.
The Y-pipe/cat. converter was replaced last week, this problem was happening prior to replacing it.
Thanks for all the suggestions, like i said, i guess you would have to hear and drive it to see what im talking about. If i nurse the pedal i can get it to run upto at least 60. EGR valve comes today ill install it tomorrow and see what happens. There isnt much i cant fix, or diagnose im pretty mechanically inclined but this one has me stumped. Will update. thanks.

 

If it isn't that I would guess your pcm is shot..thats about all I got left to guess on it.

 

id still look into that tranny. i had that issue on my 83 dodge ram wagon and it was due to the tranny having water in it but the engine would rev up like there was no tomorrow. make sure its cleaned out. idk alot about the pcm they are talking about though. is EVERY last gear doing this?

 

not sure seems like u went over everything....maybe a tourque convertor issue?