E6-350 Return To Idle Issues

[linrick1]

Hello all, I recently had the injector pump on our 89 E6-350 rebuilt and while the issues that caused me to get it rebuilt have been resolved, I now have a new problem. When I release the throttle pedal, the engine rpms quickly drop to 900 rpms, from which point it slowly drops the rest of the way down to the idle setting of 650 rpms. This is preventing the Jake brake from actuating when it should and I wind up coasting for anywhere from 5 to 20 seconds before the Jake kicks in. Also, if the road is at all rough the Jake seems to "bounce" on and off as the rpms slowly reach idle. I brought the truck back to the pump shop and explained the problem to the "technicians" that rebuilt the pump and they refused to even entertain the idea that there was a problem with the pump, telling me that not only would they not go for a ride with me so that they could see exactly what the problem was, but said that the problem was electrical, a bad clutch or pump switch for the Jake and would do no further trouble-shooting until I had replaced both switches. Despite the fact that I knew full well that the switches were good, I changed them out for new ones, thoroughly examined the throttle linkage for any symptoms of binding, increased the throttle return spring tension and ........same problem. I now have the idle stop backed about all the way out, using the jake switch as the idle stop and it works a little better but still is not right and I am at a loss as to what I should do next. Any and all ideas, thoughts or suggestions on this are greatly apreciated,sorry for the long winded post, Thanks, Rick

By the way, its a PLM pump with an Ambac govenor.

[fjh]

Hello all, I recently had the injector pump on our 89 E6-350 rebuilt and while the issues that caused me to get it rebuilt have been resolved, I now have a new problem. When I release the throttle pedal, the engine rpms quickly drop to 900 rpms, from which point it slowly drops the rest of the way down to the idle setting of 650 rpms. This is preventing the Jake brake from actuating when it should and I wind up coasting for anywhere from 5 to 20 seconds before the Jake kicks in. Also, if the road is at all rough the Jake seems to "bounce" on and off as the rpms slowly reach idle. I brought the truck back to the pump shop and explained the problem to the "technicians" that rebuilt the pump and they refused to even entertain the idea that there was a problem with the pump, telling me that not only would they not go for a ride with me so that they could see exactly what the problem was, but said that the problem was electrical, a bad clutch or pump switch for the Jake and would do no further trouble-shooting until I had replaced both switches. Despite the fact that I knew full well that the switches were good, I changed them out for new ones, thoroughly examined the throttle linkage for any symptoms of binding, increased the throttle return spring tension and ........same problem. I now have the idle stop backed about all the way out, using the jake switch as the idle stop and it works a little better but still is not right and I am at a loss as to what I should do next. Any and all ideas, thoughts or suggestions on this are greatly apreciated,sorry for the long winded post, Thanks, Rick

By the way, its a PLM pump with an Ambac govenor.

It looks like you used the old lever,

Replace the throtle lever on the side of the pump if the springs re worn it will surge and not return correctly!

[linrick1]

It looks like you used the old lever,

Replace the throtle lever on the side of the pump if the springs re worn it will surge and not return correctly!

Hi fjh, the throttle arm was replaced towards the end of last year when I was trying to cure the surging issues I was having before I got the pump rebuilt so the springs and the pivot are both tight with no play or slop. Thanks, Rick

[Rob]

Hi fjh, the throttle arm was replaced towards the end of last year when I was trying to cure the surging issues I was having before I got the pump rebuilt so the springs and the pivot are both tight with no play or slop. Thanks, Rick

Rick, I've seen those arms not be any good a couple of weeks after they were installed. I would go with Fred's suggestion and replace it again. If this is not the problem I suspect something in the governor flyweight bushings are too tight, or binding. This could be a weak spring pulling the flyweights back to the low speed setting also. Regardless, I don't think I would use the pump shop again with thier apparent attitude.

Rob

[linrick1]

Rick, I've seen those arms not be any good a couple of weeks after they were installed. I would go with Fred's suggestion and replace it again. If this is not the problem I suspect something in the governor flyweight bushings are too tight, or binding. This could be a weak spring pulling the flyweights back to the low speed setting also. Regardless, I don't think I would use the pump shop again with thier apparent attitude.

Rob

Hi Rob, we have another throttle arm in stock so I will do as Fred suggested tomorrow.(Thanks again Fred) I failed to mention in my first post that when standing next to the truck with the hood open and the engine running I run the engine up to full throttle and release it, the throttle arm will spring back through say 90-95% of its travel toward the idle position and then you can watch it creep the rest of the way to where it should be. Watching this action was what led me to believe that the problem was in the pump. As for this pump shop(D and W diesel in Oxford Mass.) I am going to speak to the shop manager tomorrow and see what he has to say about getting this right, I spent $2K to get this pump rebuilt and they had damn well better stand behind their work and correct this situation to my satisfaction. Hopefully I will have more luck than I have had so far. Thanks, Rick

[Lmackattack]

Have to ask... did you check the linkage for any binding. I had this issue after I installed a throttle lock and it was causing the pedal to stick right before idle RPM.

[Blackened]

Have to ask... did you check the linkage for any binding. I had this issue after I installed a throttle lock and it was causing the pedal to stick right before idle RPM.

Simple test would be to remove the throttle linkage and work the pump by hand to be certain if its in the pump or the linkage. I have had linkages bind near the exhaust on several occasions.

[theakerstwo]

Simple test would be to remove the throttle linkage and work the pump by hand to be certain if its in the pump or the linkage. I have had linkages bind near the exhaust on several occasions.

Do what this man has stated. The problem is with who put it on and not the rebuilder. I have seen many times this has happened. Just remove the trodle linkage from the lever and go to full throdle and then return it to idle. Make the lever go to idle. You will see that its ok. Now try to figure out what you need to do. You will have to shorten the linkage or lengthen it and also move the linkage joint down on the lever some. They should be more than one hole for the joint to go in on the lever. That maybe all you need there. Now if you have been adjusting on the throdle screw you may have to readjust.Sound like the pump shop run out of patiences with you.He knows what it was doing on the test stand and he did not want to argue about it. It would have been easy for him to walk out there and show you what the problem was.

[linrick1]

Success at last. Took the pump back off and to a different shop to be tested where they determined the flyweights were indeed binding. They repaired the issue and the pump now works as it should have all along - thanks for the help. Rick

P.S. "The problem is with who put it on and not the rebuilder."

I am the one who put the pump on and while it is well within the realm of possibility that I may have done something incorrectly (I did not) I do not subscribe to the idea that simply because an item has been repaired by a shop or garage that it has been repaired correctly.