----- Original Message -----

From: Bill Bradburry

To: Rotary motors in aircraft

Sent: Friday, September 18, 2009 8:09 PM

Subject: [FlyRotary] Re: Mixture Condition

John,

You can send your injectors to have them flow tested and cleaned for about $17 each plus about $5 each way for shipping the entire batch.  That will be about $80.

 http://www.cruzinperformance.com/fuelinj.html

Rich at cruzin performance did mine.

You can check to see if they are leaking by pulling them out of the engine with them still attached to the rail. (use a wire to firmly attach them to the rail so  they will not blow out) turn on the fuel pump.  If there is a leak they will drip.

I doubt the problem is with the injectors leaking because the engine runs poorly when on the injectors, but not on the carb.  When air flows thru the carb, fuel in the carb will be sucked into the intake.  That could cause the engine to run rough on the injectors and if the supply continues, the engine would keep running when the injectors are shut off.

But the first thing you are going to have to do is isolate the problem to either of the two systems and then fix the bad one.  As long as you keep running both systems, you are going to have difficulty determining what the problem is. Disable one or the other so there is no way it can get fuel or introduce air and check for how it runs, then do the other one the same way.  At least you will know which system is screwed.

Bill B

 

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From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of John
Sent: Friday, September 18, 2009 9:38 PM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: Mixture Condition

Gentlemen, thankyou for your input.  I talked with Bob White tonight and he thought that the #1 primary injector may be sticking open and letting the fuel run and keeping the engine running.  Try doing that on a recip engine and see how long the muffler lasts.  Not sure how to check for this condition, as when it finally stops,  I turn on the LP pumps and start the engine so the pressure on fuel injection doesn't bled to zero, putting the fuel into the standing engine, then I let the fuel burn out of the carb until it quits.  In a few minutes it will start and run normal again and will stop when you turn off the injectors and as it gets hot again it repeats the cycle.         

Does anyone know of a reasonable substitute for Mazda injectors, their price is quit steep. 

 I can plug the fuel line to carb, but I don't believe that after 7 hours of running that gas would start siphoning up to the carb and with the fuel pump and injectors off it keeps running until the fuel pressure gets down to 17#'s before it quits.  The fuel pressure is holding a steady 41 pounds when the engine is running normally.  JohnD 

From: Tracy Crook

To: Rotary motors in aircraft

Sent: Friday, September 18, 2009 4:57 PM

Subject: [FlyRotary] Re: Mixture Condition

 

With such an odd assortment of symptoms I suspect that you may have more than one problem.  This is the hardest situation to diagnose because fixing any one thing will not make it right, only change the symptoms.

If there IS a single problem, it is to be found by finding what makes the engine run with all injectors disabled.  This can't happen unless there is a major problem somewhere.  I would suggest fixing this first. 

Tracy Crook

On Fri, Sep 18, 2009 at 1:08 PM, John <downing.j@sbcglobal.net> wrote:

I have narrowed the mixture condition down to the fact that when it starts to miss up I can keep it running poorly by turning the mixture control down to minimum, but if I turn off the primary injectors switch the engine appears to run okay, the secondary injector switch doesn't seem to make any difference in the way it runs at 4000 rpm or idle.  The injector switches as well as the wiring harness I purchased from Bob and all wires are soldered and covered with heat shrink.  I checked the best I can with a light and mirror and everything looks okey under the panel.  It runs the same, rather in mode A or B.  On rereading the instructions I see that the coil disable can only be checked in mode B, so I haven't done that yet. 

I turned of the fuel pump and with the injector switch's off the engine continued to run until the fuel press was down to 17 pds. and quit.  I turned on the fuel pump (LP) to the Weber and it started immediatly.  This condition started at 7.2 on the hour meter.  I really now don't have any idea where to start looking for the problem.  JohnD