Steve Alexander

Hi Dave, I was wondering if I could get some guidance on a problem with my DZ140 . I asked this question in the pattern forum and got a few answers but wanted some confirmation before I sent it off to be fixed. The engine ran great for 70 flights. Its been used constantly for the last few months. However, during one flight it turned sour. During when checking it on the ground it won't reach peak rpm (am using a 16/12 prop) , the idle becomes very irregular and speeds up if left at idle, eventually dying. It still starts well, just won't perform. I checked the valves, and tightened them as per instructions as I thought they were very loose compared to my other DZ's. I changed fuel ( Coolpower 20/20) to confirm it wasn't a badly mixed batch, changed glow plug, and tried the engine in another airframe just to discount a plumbing issue. I still have excellent compression and the valve stems move freely. I tried the engine with the regulator screw adjusted 1/2 a turn in and out but no change. I also took the needle valve out to flush fuel through it and checked for fuel flow to and from the pump etc. The other DZ I put in the airframe runs fine on the same fuel etc. Can't think of anything else to check. Its been suggested that my pump is faulty. Any thoughts?
cheers
Steve A

Dave Shadel

Could be the pump, but try turning it in at least a full turn from where it is now and let me know if it helps.

Steve Alexander

Thanks Dave, I'll give it a try in the weekend.
cheers
Steve

Steve Alexander

Dave,
Finally had a chance to test my DZ. Wound the regulator screw in one turn and it wouldn't start. Eased it back out in 1/4 turn increments and it finally started back in the original position with same symptoms. Where to from here?
cheers
Steve

Dave Shadel

It has a bad pump. It will have to be returned for service.

Steve Alexander

Thanks for the help Dave.
cheers
Steve A