Injection pump idle adjustment.

[Mattguy]

I have my idle adjustment screw on my IP turned all the way down. This is a video of it running I don't know if there's any other way to adjust the idle.

 

[Action]

I thought idle is adjusted at the end of the throttle cable. It has been a few years.

 

[Mogman]

Is the high idle control under the dash pulled out? otherwise possibly an accelerator pedal/cable issue?

 

[Mattguy]

I thought idle is adjusted at the end of the throttle cable. It has been a few years.

There is a idle screw on the throttle linkage. I didn't know if there is any other adjustments on the IP to adjust idle.

I'm hoping that I didn't get burned on eBay. Seller stated it was idling high on his 6.2.

From the listing.
Stanadyne DB 2831-5149 Fuel Injection Pump for 6.5L Non-Turbo GM Diesel Engine HMMWV M998. I purchased this pump new and installed on my 1994 Humvee. The car supposed to come with a 6.5L engine, but at some point, the military swapped the motor with a 6.2L. This pump works ok on a 6.2L, except for the idle RPM was a bit high. I finally figured out why, so I purchased the correct pump for the 6.2L and put this up for sale. I only drove about 20 miles on this pump. However, it was installed on the truck for about 2 years. I just recently decided to do the pump swap

 

[Mattguy]

Is the high idle control under the dash pulled out? otherwise possibly an accelerator pedal/cable issue?

That's the first thing I checked. But it's not. I'm hoping this guy didn't sell me a bum ip.

 

[Mogman]

6.2 or 6.5L would not have make any difference at idle, if you thought it would act differently on a 6.5L than a 6.2L as far as idle than that was your mistake.
Even though the problem may not be fatal.

 

[Mattguy]

6.2 or 6.5L would not have make any difference at idle, if you thought it would act differently on a 6.5L than a 6.2L as far as idle than that was your mistake.
Even though the problem may not be fatal.

The 6.2 and 6.5 have different IPs, so I thought that might be the reason why he had high idle. I figured the 6.5 would have a higher fuel need than a 6.2.

 

[Milcommoguy]

The 6.2 and 6.5 have different IPs, so I thought that might be the reason why he had high idle. I figured the 6.5 would have a higher fuel need than a 6.2.

Has someone been into it? Easy to mess up the Idle spring and guide or bent the metering arm if gorilla fingers were in there fooling around... like trying to turn up the delivery and put it back together all wonkie.

Wouldn't be the first time things got bent, CAMO

 

[Mattguy]

Has someone been into it? Easy to mess up the Idle spring and guide or bend the metering arm if gorilla fingers were in there fooling around... like trying to turn up the delivery and put it back together all wonkie.

Wouldn't be the first time things got bent, CAMO

This is pic from listing. Looked new, that's why I bought.

 

[Mattguy]

I found a post about adjusting fuel pressure setting on ip. Anyone mess with this setting.

Turning a 1/4 turn counter clockwise.

 

[Mogman]

The 6.2 and 6.5 have different IPs, so I thought that might be the reason why he had high idle. I figured the 6.5 would have a higher fuel need than a 6.2.

Not how it works, there is really no practical difference between the 6.2 and 6.5L the pump adjusts the idle speed using a governor not a fixed amount of delivered fuel

 

[Mogman]

I found a post about adjusting fuel pressure setting on ip. Anyone mess with this setting.

Turning a 1/4 turn counter clockwise.View attachment 860348

That is how to turn "UP" an IP for more fuel delivery/power, has nothing to do with idle.

 

[Mogman]

Now Milcommoguy is probably close, there is a reason the IP cannot reduce the fuel enough to make it idle correctly, it is most likely a problem inside the top chamber that can be accessed, that is if there is no external problem like linkage or bent parts on the outside.

 

[Mattguy]

Now Milcommoguy is probably close, there is a reason the IP cannot reduce the fuel enough to make it idle correctly, it is most likely a problem inside the top chamber that can be accessed, that is if there is no external problem like linkage or bent parts on the outside.

Nothing bent on the outside, what can adjusted in the top cap that adjusts idle? I thought just the kill switch.

 

[Mogman]

Nothing bent on the outside, what can adjusted in the top cap that adjusts idle? I thought just the kill switch.

There are governor springs and linkage that can have rust/corrosion on or be bent.
I have changed many Roosa Master pumps, now Stanadyne but never re-built one, time to consult with a local injection service if it was me.

 

[Mattguy]

I'm wondering if a clogged injector would cause it to idle like this. When I first got it running it didn't have this high idle.

Or possibly a clogged return line.

 

[Action]

Is the throttle return spring installed?

 

[Mattguy]

Is the throttle return spring installed?

Yes, throttle return installed.

 

[Mogman]

I do not think a clogged injector would do that, I have seen them fail where they leak causing an early detonation (knock) but have never seen a clogged injector, it would seem something would have to break as you cannot compress a liquid so something would have to give.
I assume you have taken a screwdriver and have tried to lightly "force" the throttle lever towards idle?
Did it go into "high idle" the first time you pressed the accelerator?

 

[Mattguy]

I do not think a clogged injector would do that, I have seen them fail where they leak causing an early detonation (knock) but have never seen a clogged injector, it would seem something would have to break as you cannot compress a liquid so something would have to give.
I assume you have taken a screwdriver and have tried to lightly "force" the throttle lever towards idle?
Did it go into "high idle" the first time you pressed the accelerator?

It goes to high idle as soon as started. I have the throttle return as far back as it goes. I'm going to check return line to see if it's clogged.