This compressor speeds up and slows down constantly when above idle. Does not run at a happy speed. This was a unit I restored and best I remember it was not doing that before. I have 2 identical units. The one is fine but not this one. I have swapped the regulator that sits on top of the oil air tank and still has the same issue. Also rebuilt another air inlet valve and same problem.I have spoken to atlas copco tech support and we have not figured this one out. It makes air just fine but it should run steady but does not. I am lost at this point as to where to look. And I also put a ball valve in at the air control line that goes to the throttle control. When I close the valve it runs steady. That leads me to think the engine governor is fine. Any help would be appreciated.
So thanks to the admin He was right! I do have leaks at 2 fittings. When I did the restore on the compressor I had some damaged control hose fittings and so I cut these off and used 1\4" compression ferrules. They both leaked. Some research says these are not .25 in but 6mm. The original ferrules are something special that I can not find anywhere.
Update on this issue. After repairing the small leaks in the control lines I still have the same issue