Attention: TDR Forum Junkies 
1994 2500
The problems started immediately after I had my “500 hp” build last fall (see most mods in footer). Problem number 1: Severe bucking in the 800-1100 rpm range under low throttle. Problem # 2 Engine does not hold proper idle rpm in gear (ok in neutral). Worse, many times idle will drop to ~250 rpm suddenly after putting the truck in gear. Only solution has been to put her in neutral until the traffic light changes, then give her throttle. This problem has become pronounced and regular in the past few weeks, used to be in winter occasionally. When at cruising speed if I took my foot off the throttle rpm in the good old days rpm would drop to ~800; now it drops to 500.
The first problem was partially solved by removing the center spring of the new governor springs. I was told that would change things from a 4K installation to a 3k. It appears this was a band-aid fix. It still bucks around 900 rpm under light throttle, but I could live with that, though there has to be a solution. The second problem persists and has gotten worse as the weather warms (coincidence?). It is coupled with relatively hard stating. Used to take only a split second to fire…even after the build. Now it takes several seconds (maybe 5 turns or so). The big clue in my humble opinion is that if I give a little pedal on start-up she fires right up like the old days. This suggests to me a fuel delivery problem. The IP was not replaced at the build, but it was a rebuilt one (Piers) that I had replaced around the 200k mark. Same basic pump as stock, mildly souped up. There were ~ 300,000 miles on her at 500hp build. The builder seems to think I need a bigger IP, but I wonder if timing is the issue or something else. Almost forgot: There is a noticeable vibration when she drops below 15mph. If I take it out of gear it disappears. A few weeks ago the fuel return line ruptured slightly and I had it replaced.
I have had advice from two well-known diesel experts (Harry at Peaks and Casey at H&H trucks) indicating that the pump was probably not properly calibrated when the new gov springs were installed. I am taking it back to the builder, but would like any other ideas that TDR members might have.
Thanks
The problems started immediately after I had my “500 hp” build last fall (see most mods in footer). Problem number 1: Severe bucking in the 800-1100 rpm range under low throttle. Problem # 2 Engine does not hold proper idle rpm in gear (ok in neutral). Worse, many times idle will drop to ~250 rpm suddenly after putting the truck in gear. Only solution has been to put her in neutral until the traffic light changes, then give her throttle. This problem has become pronounced and regular in the past few weeks, used to be in winter occasionally. When at cruising speed if I took my foot off the throttle rpm in the good old days rpm would drop to ~800; now it drops to 500.
The first problem was partially solved by removing the center spring of the new governor springs. I was told that would change things from a 4K installation to a 3k. It appears this was a band-aid fix. It still bucks around 900 rpm under light throttle, but I could live with that, though there has to be a solution. The second problem persists and has gotten worse as the weather warms (coincidence?). It is coupled with relatively hard stating. Used to take only a split second to fire…even after the build. Now it takes several seconds (maybe 5 turns or so). The big clue in my humble opinion is that if I give a little pedal on start-up she fires right up like the old days. This suggests to me a fuel delivery problem. The IP was not replaced at the build, but it was a rebuilt one (Piers) that I had replaced around the 200k mark. Same basic pump as stock, mildly souped up. There were ~ 300,000 miles on her at 500hp build. The builder seems to think I need a bigger IP, but I wonder if timing is the issue or something else. Almost forgot: There is a noticeable vibration when she drops below 15mph. If I take it out of gear it disappears. A few weeks ago the fuel return line ruptured slightly and I had it replaced.
I have had advice from two well-known diesel experts (Harry at Peaks and Casey at H&H trucks) indicating that the pump was probably not properly calibrated when the new gov springs were installed. I am taking it back to the builder, but would like any other ideas that TDR members might have.
Thanks
