Sluggish Acceleration Hummer H1 6.5 non turbo Diesel

[whitehumh2]

Wow that is a good deal! Pumps are $1500 to $2000 around here!

[GreenMeanie]

OK i have to chime in again.
If in park, you step on the throttle and the revs go all the way up it is not an injection pump problem. At least not an internal one.
Taking the truck out of park uses the manual valve inside the trans to mechanically move the shift valve to allow fluid to pass into the receive chambers. At the same time fluid impinges on the pressure switch which in turn sends a closed circuit signal via the trans external harness, to the trans controller telling it what gear you selected, which should output and return a 5volt reference from the TPS.
I would ring out all the applicable wires involved before spending a pile of money on parts. Its got to be an electrical issue between the pressure switch in the trans, the TCM, TPS and/or Throttle peddle. Given the throttle works in park and the TPS is new and the trucks revs up in park it leaves the wiring between the transmission and the TCM which is the pressure switch in the transmission and/or the quad on the Transmission control module.
My 97 is electronic so its a different layout than on the NA but i imagine the transmission harness that goes from the transmission to the TCM runs under the engine cover where the shifter is. There is a lot of rubbing that takes place in this area.
Wish i had the AMG section 12 wiring schematic for your year so i could trace it out for you.
Beyond that the issue could be ominous but in my opinion it would be transmission related. For example the low fruit is the manual valve inside the transmission valve body, the pressure switch which can be accessed easily by dropping the transmission oil pan and servicing the valve body. Its prudent to replace all of these parts below if doing a valve body service. They cost about 100 bucks or so.There is also the external harness from trans to controller and a trans filter that are not listed below. 
 5714925                                     1-2 sol
5714926                                     2-3 sol
5744098                                     Presure switch
5714373                                      Presure control
5744093                                     TCC sol
5715037                                      wiring harness

[GreenMeanie]

I think its time we had a Hummer meet at Sonny's garage. Heated hopefully. Lets get this puppy back on the road!!
Sonny where are you located? Do you have a heated garage for wimps like me LOL?? Do you have the underbody protection installed?? How about the doghouse cover?? What applicable tools do you have there??
I would say between a few of us we can get a C service done and fix, or at the very least diagnose these issues, in an afternoon barring rusty seized bolts on the underbody protection.
Nothing is more fun than fixing these trucks anyway.
Give us your thought on that Sonny!!

[Roy]

Kevin , remember 1 thing, it is a mechanical injected truck. Cable throttle not electronic.
 
There is no issue with the trany due to motor not having enough guts to rev up past 1200ish rpm in gear. The stall rpm for a trany is 1800 rpm. In neutral it can rev but not with yest. Once the motor can rev in gear, then we will check other options.

[GreenMeanie]

Here is a link for a good diagnostics chain to follow for fuel related issues. I'm still not convinced that is what our problem is.
http://oregonfuelinjection.com/pdf/stanadyne-pump-diagnostic-troubleshooting.pdf
 
If section 1, part 1-5 have been checked out and confirmed then 6 is a possibility. All section past 1 deal with a no start. At this point we haven't confirmed 1-5 conclusively.
Doesn't seem to meet the criteria of our problem in my mind. I say pull the electrical cable out of the side of the transmission and see if it goes around the block LOL
 
Side story on the speed control fuse. Works on a turbo not sure about NA but i would think it would.
I am adding a switch under my dash to disable the speed control fuse for computer/TCM shifts. Turns the truck into a rocket but the shifts are like bang LOL Does give an edge when the Duramaxes pull up and make you wanna breath smoke. Its not bad for the transmission but isnt exactly comfortable and you lose your speedo. Anyway Off topic.
 
Lastly a stuck or dragging TCC can cause the power issue according to Page one ATSG 4L80 troubleshooting manual under Loss OF Power. Pin S on the trans connector (black wire) is the ground for the TCC -PWM solenoid. Pin E (red wire) is the signal spliced into three going to SOL A, SOL B, TCC PWM.
This is from 1993 circa so should apply to the 95 as there were no new changes for those years til 96.
I wouldn't count on the transmission cable in the hummer to have the same color code as the internals of the transmission but the pins are the same..
The other issue that i had thought of earlier in the thread was the the pressure switch outputs on pins N (black), R (white), P (blue) which in various combinations send shift point data to the TCM and interpolated with the TPS, speed sensor, rpm, CPS etc. Some of those sensors may not be applicable on the NA.
Anyway food for thought.

[GreenMeanie]

Im adding a few links to some good reading.
Great thread on the fuel system etc.with several sections.
http://www.flashoffroad.com/Diesel/troubleshoot/troubleshoot.htm
Flash Off Road Main Page for all issues.
http://www.flashoffroad.com/humdefault.htm
6.5 Guru Land- need to sign up to see pics. Very worth it.
http://www.thetruckstop.us/forum/forums/6-2-and-6-5-diesel-engines.92/

[Roy]

Truck can move on its own,forward and reverse, Only issue is no throttle response in gear --under load. Saying it is a mechanical injected motor means, that if there is fuel and air it will run. A very little more fuel(unused fuel) and it will rev in park--no load. It will need more fuel to rev motor under load. Since the motor does not rev in gear past a fast idle, lack of fuel is the only answer.  Fuel pump replace .
I have been to truck and seen what is happening.
This problem is not electrical nor trany related ,in my opinion.
 
An under lying issue of hard shifting may be the TPS,but it is now replaced and awaiting power to try and see is this issue is resolved.

[Skenth]

Sorry guys..I was out of town and just got back. Nice to see a lot of brains working trying to figure out what's going on. I'm not a mechanic (Roy can confirm that after seeing how I worked on my truck with his guidance 2 sundays ago when he walked me through replacing the fuel pump..haha. I enjoyed it but was disappointed when it didn't solve my problem) but it's a bit more than what I can handle. I had dropped it off at Phils garage in Caledon before leaving and he's thinking along the same line as Roy. After all the diagnosis, it seems to be a faulty fuel injector pump. I asked him to put a new one (instead of a rebuild one) because of labor involved in changing the pump seems quite extensive and I don't want to have to go through it again...hopefully it'll last me next 10yrs!


Truck is back on the road. Runs better than before. Seems like I'm getting more power out of it and is quieter and feels light and quick. Maybe it's running better and fast since I had to empty my wallet!

[Monk]

Wow great to hear.!!! Yes I hear ya, even when I look at my 96 inj pump ,lol I get scared with the amount of labour to get to it,and the

Working area I bet is tight as hell, . I'm sure lots of swearing,hehe

[whitehumh2]

Maybe it's running better and fast since I had to empty my wallet! The weight of the $$ bills was slowing the truck!

Glad to hear that your H1 is fixed and working great!

Btw, if emptying your wallet makes your H1 go faster and run better....you could empty your wallet my way!

Your Hummer will go faster and I will have extra funds for upgrades...Sounds like a Win-Win to me!


Enjoy your perfectly running H1!