John deere 4020 miss

timgc78

Member
Hello critical thinkers out there. I have a 67 jd 4020. No matter the temperature when I first start the tractor it runs fine for a few seconds then begins to have a consistent dull miss that eventually settles out when the engine warms up. I recently replaced the injectors and lift pump. Injector pump was over hauled less than a year ago. The tractor had this same symptom with the old injectors and lift pump before the injection pump was rebuilt. Any body out there have this issue or any idea how to remedy the problem?
 
how long has it been since the valves were adjusted, wouldn't hurt to check valve lift ,are you loosing power or getting any light blue or off white smoke when it acts up?
 
(quoted from post at 14:00:26 03/19/15) how long has it been since the valves were adjusted, wouldn't hurt to check valve lift ,are you loosing power or getting any light blue or off white smoke when it acts up?
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What does the blue or off white smoke, mean? Mine does this once in a while. thanks for the info. Brent[/i:b9ebde7505]
 
under normal conditions the light smoke could be nature of the beast with no problems,but if one is missing it could mean unburnt fuel or worse coolant
 
Don't think mine is coolant seem to have same amount all the time, think I may need to get new injectors I already done the pump cause it gave up the ghost. Brent
 
(quoted from post at 17:08:34 03/27/15) did you check the inj opening psi. they need to be all the same when run with rotor pumps

I don't know how to do that or if I even can, I know these have a fair amount of hours I think I will just get some new ones. Is there a brand that is better than others or they pretty much all good if you get from a reputable place. thanks Brent
 

Checking injector pop off pressure requires a special test hand pump with a gauge & reservoir to hold some fuel for testing. Attach inj to pump then move handle repeatedly until valve in inj opens. One must observe gauge while pumping handle to determine opening pressure.
 
(quoted from post at 04:09:05 04/01/15)
Checking injector pop off pressure requires a special test hand pump with a gauge & reservoir to hold some fuel for testing. Attach inj to pump then move handle repeatedly until valve in inj opens. One must observe gauge while pumping handle to determine opening pressure.

Ok thanks for the info Jim. Brent
 

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