|
|
Central South Dakota | I am looking for ideas. I recently did a complete overhaul on an 855 cummins. I did not rebuild the fuel pump as it had very few hours on it before we decided to tear the engine down. Now the truck runs great, but it returns to idle too slowly, and it almost dies off before it comes back up to idle. It has run long enough it should have all the air out and I don't see any external leaks when not running. Thanks in advance for helping. |
|
| |
|
Leeds, North Dakota | starts fine? after sitting overnight, is foot throttle sticking in cab, have seen them git full of sh't, linkage binding, leaning to the latter, scott. |
|
| |
|
Southeast North Dakota | I had a "rebuilt" injection pump on a 875 do that. It turned out that there was in internal air leak in my "rebuilt" pump. I keep saying "rebuilt" like that because I had the pump re-done again and I was told at that time the pump was basically worn out and shouldn't have been sent out the door the last time. My advice would be to have your "rebuilt" pump checked out again, it might need to be "REBUILT" again LOL! JMHO. |
|
| |
|
Leeds, North Dakota | yes i agree, that is my gut feeling, hope i'm wrong, scott. |
|
| |
|
| How does it pull? A Cummins will be slow coming to idle if the pump isn't getting enough fuel flow (plugged filter, fuel line, etc.) but if it seems to pull like it should, it is probably getting enough fuel, so I would guess maybe the pump needs to be looked at. |
|
| |
|
Iowa | If the middle o-ring on an injector got nicked when installing you may also see that symptom. The middle o-ring separates the fuel supply and return to the injectors. You may be already familiar with this but, STP is a good lubricant for the injector o-rings to prevent nicks and cuts. I wouldn't tear it apart until you did the simple stuff(throtle linkage, fuel filters, etc.) but a set of o-rings is cheaper than another pump. Good luck and I hope it's something simple. |
|
| |
|
Central South Dakota | Linkage moves just fine, brand new fuel filter, always started very good after sitting a while, but now has started to hesitate but always starts. It doesn't seem like it is esponsive enough when you snap the throttle a little. Haven't pulled it hard yet but seems OK bobtailing. I am leaning towards the pump also. |
|
| |
|
Leeds, North Dakota | lets start from square one, is rack set correctly, did this happen after overhual, what does data plate say for setting injectors, zero lash, .005 to .006 inch pounds, or does it call for x amount of lash, one that comes to mind is .228 lash, get info off data plate, when you run rack, set cold, intake valves are in, exhaust out, did you have problems setting rack, one thing you need to do, storke injectors, before setting, need more info, if this happened after overhaul, top end is not right, got questions email in profile, give me your #, reason i'm asking if had trouble setting valves and injectors, have seen pin shear on accessory drive, don't know where ya are, scott. |
|
| |
|
Central South Dakota | This did just start after O/H. Injectors are set with lash, don't know the number off the top of my head, somewhere in the same neiborhood as valves. It's a Big Cam 4 if that helps. Top end set with no trouble, did it cold of course, rolled it over a couple times and re-checked and looked good. CPL is 675 I do remember that. I appreciate your insights. Brett |
|
| |
|
Leeds, North Dakota | brett, need #'s off data plate, need to know what valve lash says and what injector setting is, something is wrong with rack, don't run it, data should be on left hand side of motor, vertical aluminum plate on accesory drive, valves are set intake ar .011, exhaust .023, difference in injectors non stop top or top stop, data on plate will tell me what i need to know, you set valves and injectors per cummins a b c, to set rack, scott. |
|
| |
|
Central South Dakota | I will have to get back to you on dataplate #'s. Dataplate was never there when we got it, I had to get a printout from cummins. Injectors are not top stops. I will re-run the top end when I get back to it, just to make sure, it is easy enough to do and can't hurt anything. thanks scott |
|
| |
|
Leeds, North Dakota | if not non stop injectors spring in injector that comes out, gotta use cummins tool, scott. |
|
| |
|
Central South Dakota | I re-ran injector settings(72 inch pounds for the aluminum rocker boxes) and did not make any difference. My only issue right now is the return to idle problem. I even slowed down the low idle setting and didn't change. This is just my weekend project, so I don't get a chance to work on it as much right now. Thanks for any more ideas. |
|
| |
855 Cummins ?
