Canadian Hummer Club Forums

A new symptom just appeared on my H1:



today I was going up hill and the motor didn't seem to have any power. I floored it and I couldn't get the RPM higher than 2000, but all of a sudden, it seems like it was running on all 8 again and regained power! It didn't it again later but this time it went from power to less power. I noticed the RPM when from 2000 to 1800 without changing gears or release gas pedal. It's like it's shutting off some cylinders intermittently.



Any clues of what could be causing this??

[quote name='3Dinnovations' timestamp='1333326869' post='35825']

A new symptom just appeared on my H1:



today I was going up hill and the motor didn't seem to have any power. I floored it and I couldn't get the RPM higher than 2000, but all of a sudden, it seems like it was running on all 8 again and regained power! It didn't it again later but this time it went from power to less power. I noticed the RPM when from 2000 to 1800 without changing gears or release gas pedal. It's like it's shutting off some cylinders intermittently.



Any clues of what could be causing this??

[/quote]



First place to start would be a PMD, it is the only thing that has that much control over the engine!

Yes, Id agree that it could be the PMD. Do you have a Scanguage II? The reason I ask is that the guage functions of the SG2 can help diagnose if there are other factors at play. Less likely, but you could be experiencing tranny slippage or issues, as well, but without certain outputs (tranny temps, etc) you wont know.



Nice added feature of the SG2 is its ability to read/clear engine codes, should you throw a code.



Whens the last time the PMD has been changed?



What year is your truck?

[quote name='Hesh' timestamp='1333347047' post='35830']



Whens the last time the PMD has been changed?



What year is your truck?

[/quote]



I changed my PMD last fall, I only have 3000 miles on it, plus it's the gray Stanadyne. My truck is a 1999. I also noticed that my truck seems harder to start in cold weather. Usually at -3C it would start right away, but lately it cranks a bit more. I thought it was the glow plugs, but it could be something else related to the power issue.

[quote name='3Dinnovations' timestamp='1333358961' post='35832']

I changed my PMD last fall, I only have 3000 miles on it, plus it's the gray Stanadyne. My truck is a 1999. I also noticed that my truck seems harder to start in cold weather. Usually at -3C it would start right away, but lately it cranks a bit more. I thought it was the glow plugs, but it could be something else related to the power issue.

[/quote]





I think it is time to rebuild your injection pump!



There are a multitude of other sensors on the pump that the PMD relies on to make decisions if one of them is on the way out then you would have this type of problem.



I don't think it can be the tranny, normally if it would be slippage the RPM would go up not down and if it got really bad it would default to 2nd gear.



Has your smoke increased?



Did the problem only start with this tank of fuel? Did you get fuel from a strange station that you normally don't fuel at? This is also a possibility!



Before you replace any parts, start with some good fresh fuel and a new fuel filter and make sure to drain the water separator and see if the problem is corrected.



Kev

Update: Symptoms still on-going



Condition: Intermittent loss of power on my H1. I noticed last night that it was spewing a large amount of smoke when loss of power occurs.



Repairs done so far:



1) Changed Injection pump

2) New PMD (Gray)

3) New oil pressure sensor

4) New Air filter

5) New lifter fuel pump



With this update, does anyone have an idea what I should try next?



P.S. I have a spring Heath Mechanical Wastegate controller.

Is it throwing any codes?

[quote name='Hesh' timestamp='1336935545' post='37037']

Is it throwing any codes?

[/quote]



No codes!

Hey Scott,



what about the injectors?



Did you do those yet?

[quote name='Polar Bear' timestamp='1337049590' post='37139']

Hey Scott,



what about the injectors?



Did you do those yet?

[/quote]



No. I was hoping not to have to do this, but it would probably be the next step!