Injection pump idle adjustment.

[Mogman]

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.

What I meant was, you said at first it did not idle high, when did it start again (as the original owner stated it was idling high) after you installed the pump.
I would be willing to bet ether there is rust in the gov. housing or somebody bent something in there trying to turn up the pump.
I have never seen a return line do that, usually runs like crap and barely idles, I am not sure why you are looking for an external problem as the seller told you is was not working correctly to begin with.
Would not matter that it was a 6.5L NA pump on a 6.2L as there is not a nickles worth of difference between them, not sure why you assumed that it would take more fuel to idle a 6.5L VS a 6.2L, there is only 300CC difference and basically the same engine and again not how the pump works anyway.

 

[Mattguy]

What I meant was, you said at first it did not idle high, when did it start again (as the original owner stated it was idling high) after you installed the pump.
I would be willing to bet ether there is rust in the gov. housing or somebody bent something in there trying to turn up the pump.
I have never seen a return line do that, usually runs like crap and barely idles, I am not sure why you are looking for an external problem as the seller told you is was not working correctly to begin with.
Would not matter that it was a 6.5L NA pump on a 6.2L as there is not a nickles worth of difference between them, not sure why you assumed that it would take more fuel to idle a 6.5L VS a 6.2L, there is only 300CC difference and basically the same engine and again not how the pump works anyway.

When looking up part numbers for a 6.2 vs 6.5 engine it shows the piston in the pump to be a different size and different pressure. I didn't realize that the pumps weren't that much different. I guess the seller of pump must have not had the correct information about the pump and I went according to what he said in the listing.

 

[Mogman]

If the IP was working correctly it would continue to reduce the amount of fuel all the way to cutoff trying to reach correct idle speed.
I would think the only two choices you have now is to pop the top off and see if you can figure out what the problem is or pull the IP and have it serviced.
The only problem you will have is most diesel pump service shops no longer actually service the DB2 and they will only swap it for a rebuild.
The only one I know of in my area is Victoria Diesel Service in Victoria TX, but I have not had any dealings with them so I cannot advise..

 

[Mattguy]

If the IP was working correctly it would continue to reduce the amount of fuel all the way to cutoff trying to reach correct idle speed.
I would think the only two choices you have now is to pop the top off and see if you can figure out what the problem is or pull the IP and have it serviced.
The only problem you will have is most diesel pump service shops no longer actually service the DB2 and they will only swap it for a rebuild.
The only one I know of in my area is Victoria Diesel Service in Victoria TX, but I have not had any dealings with them so I cannot advise..

I have a Stanadyne dealer 5 miles from my house, so I am going to reach out and see about a rebuild. I wish I would of know this before I installed this. I really don't feel like tearing the top of the motor apart again.

 

[Mogman]

I have a Stanadyne dealer 5 miles from my house, so I am going to reach out and see about a rebuild. I wish I would of know this before I installed this. I really don't feel like tearing the top of the motor apart again.

It would certainly not hurt to have a conversation with them, do not believe anything I say unless they concur.

 

[Mattguy]

It would certainly not hurt to have a conversation with them, do not believe anything I say unless they concur.

I just got off phone with Diesel USA Group in Crown Point, IN. Told me if linkage is as far back as it will go, then to pull top cap and counter clockwise on the allen screw with cap off til I get idle at what it should be at. He did tell me if I pull the cover while its running its going to be shooting diesel out.

 

[Mogman]

I just got off phone with Diesel USA Group in Crown Point, IN. Told me if linkage is as far back as it will go, then to pull top cap and counter clockwise on the allen screw with cap off til I get idle at what it should be at. He did tell me if I pull the cover while its running its going to be shooting diesel out.

Did he explain what Allen bolt? it certainly is not the one in the previous picture as there has to be linkage removed and the crank must be stationary so that one could never be adjusted while running, in any event it is real easy to just bolt the top back on then if you are wrong just pull it back off.
Be very careful, for sure at least get your YouTube certification on how to get the stop solenoid seated correctly or it will cause much grief, you will feel it being spring loaded as you install the cover, another reason not to run it with the top off if you really needed one is you would have to reach in and manually manipulate the stop linkage because the stop solenoid will not be in place...

 

[Mogman]

I am not saying the guy was wrong, actually it makes perfect sense that someone could go in and try to turn up the fuel on a DB2 pump and turn the wrong screw 1/4 turn to the right, but this is the inside of a DB2 pump and I do not see what he is talking about, I can say with some confidence that it is not the fuel screw shown in the other post, that just turns up max fuel.

As you can see the rod with the springs must be removed to get to the "fuel" screw as shown in the other post.

 

[Mogman]

One thing to look for when you pull the top is the throttle control shaft, in the picture above it is NOT in full idle position.
Look closely at this picture the throttle control shaft is not pushing the golden color bar to the the right, the "cut" in the shaft is at a perfect right angle to the bar.

That is the throttle, that bar is only moved maybe 1/8- 1/4" from idle to WFO

Edit, I should have said parallel instead of right angle.....

 

[Mogman]

You may also want to look at A in this picture, it must be removed to remove the shaft and springs to get to the "fuel" screw and see if it has been tampered with.

 

[Mogman]

Also notice in post 29 how close the bar is to the throttle shaft when in the idle position, if there is much gap between them it could mean that shaft is not completely returning to the idle position which would cause it to idle fast, seems that hardware A in the above picture could affect that shaft.

 

[Mattguy]

You may also want to look at A in this picture, it must be removed to remove the shaft and springs to get to the "fuel" screw and see if it has been tampered with.View attachment 860436

I did notice the plastic cap was missing on A when I received the IP. My original off my truck still had plastic cap on it. I did ask the seller if he had made any adjustments to the IP while on his truck and he said no. I don't think I believe him. Something was tinkered with.

I took my old IP apart first so I can get an idea of how everything works. It's junk now, the rebuilders said if its frozen, its most likely corroded inside.

 

[Mattguy]

When first starting I forgot to mention it does surge a few times before staying at high idle.

 

[Mattguy]

Is there a cold start solenoid on the DB2? I'm reading all the standayne manuals I can find.

 

[Mogman]

Is there a cold start solenoid on the DB2? I'm reading all the standayne manuals I can find.

Yes but it should not have that much effect, you should have had it unplugged while diagnosing the problem

 

[Mattguy]

Yes but it should not have that much effect, you should have had it unplugged while diagnosing the problem

Where is cold start solenoid, is it on pump?

 

[Mogman]

Where is cold start solenoid, is it on pump?

It is the second wire attached to the IP

 

[Retiredwarhorses]

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

without going through every respons, I would never, ever install a pump someone took out, or a used pump unknown to me..ever, that’s an invitation to a waste of many hours and having to buy a new pump.

now, have you removed the throttle cable and the idle changes? What happens if you force the throttle linkage to idle and hold it down.

 

[Mattguy]

without going through every respons, I would never, ever install a pump someone took out, or a used pump unknown to me..ever, that’s an invitation to a waste of many hours and having to buy a new pump.

now, have you removed the throttle cable and the idle changes? What happens if you force the throttle linkage to idle and hold it down.

I know, but thinking that someone that sells tons of HMMWV parts on Ebay would try and scam someone by listing a IP that he says was fully functioning except that it was not for a 6.2. It was a 400 dollar IP and I'm out my labor of having to remove and reinstall. Pretty sick of getting scammed on ebay now a days.

 

[Action]

I know, but thinking that someone that sells tons of HMMWV parts on Ebay would try and scam someone by listing a IP that he says was fully functioning except that it was not for a 6.2. It was a 400 dollar IP and I'm out my labor of having to remove and reinstall. Pretty sick of getting scammed on ebay now a days.

In post #4, you pasted the sale description. The seller called the hmmwv a “car” and said it idled high.