Idle/ Low RPM Issues

[Floridianson]

Have you checked you delivery valve.

 

[searls84]

Have you checked you delivery valve.

The head on it is new.. I assume that it should be good?

So I decided to postpone sleep and work on the truck this morning (I work nights, 8p-9a). I went ahead and tore down one of the governor assemblies on one of my parts pumps and pulled the springs on the pump on the truck and compared them. There was no difference between the two and no springs were broken. I'm waiting on a bore scope from a friend to check the "centrifugal weights". So far the governor appears to be normal. What defects would I be looking for with the weights? Are they ok as long as they are attached and move freely or is there something minute I need to be searching for?

A note to future readers, nothing comes flying out when you pull the back cover to access the governor springs. It's very simple to do and the springs and shims stay put.

 

[Floridianson]

Well you checked most everything so delivery valve and then the overflow valve. I don't know if your new Head is from China but I don't trust China to have our best interest in mind. If it is from the US then you know we grow some good herb here indoors. Won't take but 15 min. to check both.

 

[rustystud]

The head on it is new.. I assume that it should be good?

So I decided to postpone sleep and work on the truck this morning (I work nights, 8p-9a). I went ahead and tore down one of the governor assemblies on one of my parts pumps and pulled the springs on the pump on the truck and compared them. There was no difference between the two and no springs were broken. I'm waiting on a bore scope from a friend to check the "centrifugal weights". So far the governor appears to be normal. What defects would I be looking for with the weights? Are they ok as long as they are attached and move freely or is there something minute I need to be searching for?

A note to future readers, nothing comes flying out when you pull the back cover to access the governor springs. It's very simple to do and the springs and shims stay put.

No, nothing special. They can break but you will see that very clearly. There is one more thing to check while your in there and that's the sliding sleeve bearing. Just make sure it moves freely. Then start checking the "delivery valve and overflow valve like Floridianson mentioned. If nothing helps then the problem could be in the front advance unit which means the pump is coming off. If you must pull the pump I would get a good used one from someone and try that before I would rebuild the old injection pump. Who knows, maybe the problem is somewhere else. This way you can eliminate the injection pump as the problem.

 

[Floridianson]

What is the news. Was thinking if you have not found the problem then start simple. Recheck timing your timing. Both timing marks on and Head will be one tooth to the rear.

 

[searls84]

What is the news. Was thinking if you have not found the problem then start simple. Recheck timing your timing. Both timing marks on and Head will be one tooth to the rear.

Sorry for not posting back sooner, been busy with work. I think I got it figured out. After checking everything that had been mentioned above and thinking everything over, I decided to start back at the beginning and re check EVERYTHING I had done to the fuel system since installing the motor in the truck. Everything was fine until I got to the fuel shut off rod. With the engine cold it seemed a little loose so I tightened it up a little but to the point where it still moved freely and took it for a drive "around the block." After the truck started getting warm it would hardly even run, I had to keep the throttle cable pulled out just so it wouldn't die, it died once and I was unsure if it was even going to start again. So once I got back home I re checked the fuel rod and lo and behold it was very tight! So with the engine at running temp I loosened it up to where it would move freely and took it out for another drive. On this test run it ran perfect, no stalling or hunting for idle.

So here is what I'm thinking. I replaced the oring on the shut off rod before I installed the motor and had a chance to really run it for any length of time. I'm guessing that when the engine would warm up to operating temp the new oring would swell and cause the rod to become "sticky" not allowing it to "float" back and forth as it should when running. I'll need to drive it more over the next couple weeks to get a definitive answer, I'm not going to say all is good after just 2 20 min trips.

I had done the orings on 8 previous trucks and never had this issue, I'm wondering now if the orings I installed on this pump are an inferior quality or just operator error? Guess time will tell!

Thanks everyone for the input and help working through this! Even if this may have ultimately been a simple fix I learned alot about the injection pump and realized they are not as daunting and scary to mess with as I had previously thought!

 

[Floridianson]

Great glad you got it figured. I think the O ring that is listed is to thick. The ones I got with the Ambac Heads was thin and I never had problems with the tighten up of the control assembly. I feel to thick and it puts the control in a bind when we torque it down to specs.

 

[Troop462]

Sorry for not posting back sooner, been busy with work. I think I got it figured out. After checking everything that had been mentioned above and thinking everything over, I decided to start back at the beginning and re check EVERYTHING I had done to the fuel system since installing the motor in the truck. Everything was fine until I got to the fuel shut off rod. With the engine cold it seemed a little loose so I tightened it up a little but to the point where it still moved freely and took it for a drive "around the block." After the truck started getting warm it would hardly even run, I had to keep the throttle cable pulled out just so it wouldn't die, it died once and I was unsure if it was even going to start again. So once I got back home I re checked the fuel rod and lo and behold it was very tight! So with the engine at running temp I loosened it up to where it would move freely and took it out for another drive. On this test run it ran perfect, no stalling or hunting for idle.

So here is what I'm thinking. I replaced the oring on the shut off rod before I installed the motor and had a chance to really run it for any length of time. I'm guessing that when the engine would warm up to operating temp the new oring would swell and cause the rod to become "sticky" not allowing it to "float" back and forth as it should when running. I'll need to drive it more over the next couple weeks to get a definitive answer, I'm not going to say all is good after just 2 20 min trips.

I had done the orings on 8 previous trucks and never had this issue, I'm wondering now if the orings I installed on this pump are an inferior quality or just operator error? Guess time will tell!

Thanks everyone for the input and help working through this! Even if this may have ultimately been a simple fix I learned alot about the injection pump and realized they are not as daunting and scary to mess with as I had previously thought!

What you describe is exactly what my Deuce is acting like. I can't wait to see if this solves the problem. It has done it from the day I purchased the truck. Every stop, low idle, sometimes recover, sometimes not. I would have to tap the accelerator to keep it running. Now, after warm up, low idle, tries to recover but dies.

 

[Floridianson]

Troop have you checked the fuel control for free movement? Have you or anyone played with the main fuel adjustment and is the FDC bypassed. One thing I would like to add is use a good fuel additive and don't be afraid to double up or triple up on the dose for the first time. This might help with gummy deposits and also helps raise the cetane level. Don't know why some use two stroke oil or motor oil as a fuel additive. They say two stroke is high on the list for lubricity and it might be but it does not clean the fuel system or as said brings up cetane.

 

[Troop462]

Troop have you checked the fuel control for free movement? Have you or anyone played with the main fuel adjustment and is the FDC bypassed. One thing I would like to add is use a good fuel additive and don't be afraid to double up or triple up on the dose for the first time. This might help with gummy deposits and also helps raise the cetane level. Don't know why some use two stroke oil or motor oil as a fuel additive. They say two stroke is high on the list for lubricity and it might be but it does not clean the fuel system or as said brings up cetane.

I have not checked the fuel control. How would I do that? No one has played with the main fuel adjustment. My guess is that the FDC is not bypassed. I will have to check.

 

[rustystud]

I have not checked the fuel control. How would I do that? No one has played with the main fuel adjustment. My guess is that the FDC is not bypassed. I will have to check.

You say you've had this same problem since you got the truck correct ? Then I would think you need to check the free movement of the fuel rod assembly. Remember fuel if allowed to sit for long periods of time will end up becoming a nasty mess of tars and other junk. There is fuel behind this rod, so if it has set for a long time the fuel could become sticky and bind the fuel shaft. Make sure it moves freely.