When I rev the engine and let the throttle snap shut my idle drops below the set point for just a second or two acting like it going to stall, but doesn't. My fuel filter and pump is almost new. My timing is advanced about a quarter inch and I have the M&H KSB spacer installed. I really haven't made any changes lately to cause this. I tried backing off the fuel screw until it would hardly run and it still did the same thing, also turned it in a full turn from where I have been running it, still no change. I plan to try backing off the timing a bit and putting my stock fuel pin back in due to some high coolant tempatures when towing but I realize that probably will have no effect on my idle problem. I had an idle problem like this a long time ago but due to my cancer meds my memory is shot so I can't remember what I did to correct it then.

 

Sure it's not the cable or springs getting hung up?
Seems just the other night a member was giving pump mod advice(dark ages tread) and in bold I saw him say DO NOT SNAP THE THROTTLE BACK FROM A HIGH RPM IDLE. I'm assuming that's throttling the cable and cable to pump bracket by hand, not letting it snap back that way. He never gave reasons as to why that is a no go.

It's gotta be from hand revving the throttle bracket, as I don't see us being able to snap the throttle back by just releasing our foot off of the pedal

 

Mine does it if you just let off the throttle. Also when I stop at a stop sign if I don't gear down.

 

Idle and full throttle are set by governor spring tension. The adusting screws set the tension, but there is no hard stop. When you suddenly release the governor spring tension from high RPM, the fly weights move toward full extension (defuel direction) in a hurry. inertia in the fly weights created by the centrifugal force will overshoot the normal idle position spring tension until the governor spring can pull the weight back into equilibrium with the centrifugal force. It overshoots.

 

The 3200RPM and higher springs are softer in comparison to the OEM making overshoot more likely.

 

That makes sense, maybe I just never noticed it. I found that hooking my KSB solenoid wire helped a lot too. I tured my starwheel up two more turns and that helped my low speed acceleration smoke also. If I start pulling a fifth wheel camper again I will probably have to go back to the stock fuel pin to get rid of the smoke and cool things off a little. When I towed the trailer with my Camero on it back from Oregon it hit 1250 degrees very easy and I was constantly having to back off the throttle and downshift on the hills. There was a ton of smoke on hills also. It ran a little warm too but it was in the upper 90's and the A/C was running.

 

I would think that having to back off to 4th on hills when towing is pretty normal behavior. As for overheating, a lot of people think that the temp gauge climbs at all it overheating. It usually isn't. In fact your efficiency goes up the hotter you can run without cooking something. That's why synthetic oil is so important. The turbo OTOH mustn't go over 1250 for more than a second or two or you'll melt the blades off.

Edwin

 

Well I solved my idle problems. The fuel screw was turned in too far, I backed it out 1/2 turn and also moved the pump back a little toward the stock position. My KSB was causing the idle to slow down when activated so I knew it was to far advanced with the timing advance kit in it. The motor sounds much better now and my idle no longer overshoots when the throttle is allowed to snap shut. I won't know how it tows until the next time I take my trailer out but I suspect the timing retard will take some heat out of the engine. May have to back the fuel off a little more to keep the EGTs down.

 

I am having the same issue with my new SCHEID diesel VE pump. It has a custom fuel pin with a 4k gov spring. I installed the pump to the stock timing "E" on the cam gear. I spoke with the SCHEID tech and he told me to try the following:
1. Rotate the pump to advance the timing
2. Bump up the idle.
3. Up my FASS lift pump pressure.
None of this has worked. I asked about the fuel/ power screw and they said that should not affect the problem. They have all the adjustments on this pump locked with paint so I dont want to adjust anything that may void warranty. This pump also has the KSB removed with a plate over the port i asked why and they said its for max fuel delivery.

wondering what I should do?. My stock pump did not have this issue.