Persistant Clogged Injectors..Turbo e

[electricsnail]

So we have a fairly new to us turbo Mooney E. It was first purchased and in the first flight our A/P took off and had one cylinders EGT's spike. He landed and diagnosed a clogged fuel injector. This happened once more on his trip home. Once it was brought home it was thoroughly inspected the fuel system drained, completely cleaned, all filters inspected and the fuel servo sent out for overhaul as no anomalies were found.

It behaved for the last 20 or so hours and on my last flight I noticed an egt spike on takeoff. I went around and landed. We cleaned the injector on the effected #2 cylinder. After finding a small clog of what could best be described looking like a thin strand of almost lead fowling....we put it together and it ran normal.

I went to fly today and this time I got an egt spike on cylinder #2 and the engine was making noticeable less power. After spiking the cylinder when blank and the engine was running less that smooth. I returned to the airport for an uneventful landing and a rough running motor....I haven't pulled off the injector as I'm waiting for the mechanic to come up tomorrow to take a look. I know that I will find another clogged injector. We have no clue where the debris is coming from as we have checked everywhere we can think of. It's very hard to tell what the debris is it is small and hard to get out with compressed air or submersion running the sample . Does anyone else have any ideas?

[jnisley]

Is it a Rajay with an adjustable waste gate? In other words turbo-normalized?

[N601RX]

I opened up my bladders a couple of years ago to replace a few gaskets and was suprised to find the amount of debree in the bottom of them that I did. Draining the fuel will not get everything out.

[jnisley]

If you have a Rayjay it's very likely coming from "boost reference system" this is the air that's introduced into the injectors coming from the air inlet box. We had a lot of problem with this years ago to the point that we installed a makeshift filtered line to see if this solves the problem which it did, (we had flecks of air filter fibers going directly to the injectors) we later installed GAMI injectors and removed to makeshift line and haven't had a clogged injector the last 400 plus hours.

[jnisley]

If you have a Rayjay it's very likely coming from "boost reference system" this is the air that's introduced into the injectors coming from the air inlet box. We had a lot of problem with this years ago to the point that we installed a makeshift filtered line to see if this solves the problem which it did, (we had flecks of air filter fibers going directly to the injectors) we later installed GAMI injectors and removed to makeshift line and haven't had a clogged injector the last 400 plus hours.

We also installed a K&N filter at the same time.

[electricsnail]

It is the m-20 turbo normalized system. Do they share the boost reference system? I assume so as we have what I though was referred to the upper deck, which balances the turbo load at the injector. Thanks

[jnisley]

I'm not familiar with how the M-20 system works so I don't know.

[Mcstealth]

An E With an M-20. I bet those flight numbers are sweet......minus the issues of course.

[jnisley]

If you have a Rayjay it's very likely coming from "boost reference system" this is the air that's introduced into the injectors coming from the air inlet box. We had a lot of problem with this years ago to the point that we installed a makeshift filtered line to see if this solves the problem which it did, (we had flecks of air filter fibers going directly to the injectors) we later installed GAMI injectors and removed to makeshift line and haven't had a clogged injector the last 400 plus hours.

  

We also installed a K&N filter at the same time.

We never determined for sure if it was fibers from the air filter or carbon coming from the turbo ducting that was clogging our injectors but I do know it was a pain in the neck.

[N201MKTurbo]

I have an M-20 turbos system, which is just a fancy version of the Rajay system. I have the Lycoming turbo injectors with the reference lines coming from the intercooler. The only filter is the intake air filter. The intake/compressor side of the system is always very clean except for a little oil downstream from the turbo. I have never had the problem you describe.

 

Is it possible your injector air hoses are deteriorated?

 

Where is the clog at the small fuel orifice or at the larger fuel/air orifice?

 

If it is at the small orifice it must be coming from the fuel system. If it is at the larger orifice it is probably coming through the air line.

[rissacher]

I'm a new Mooney owner.  We've had an M20E with the M-20 Turbo system for 6 months now and we've been plagued by the same issue (sometimes like above detected by high EGT and CHT, sometimes the cylinder going completely cold and losing power, always corrected by cleaning the offending injector, usually #2).  I was hoping we were on to something when we found this post, but after looking at our system I agree with N201MKTurbo... our clogs have been in the small fuel orifice and the air hoses (reference lines?) come in after that orifice so there doesn't seem to be a way for a problem in those hoses to make it into the small orifice.

 

Yesterday we drained the fuel and cleaned out the fuel bladders where there was quite a bit of debris similar to what we are finding in the injectors (black specs, unknown material).  The bladders are fairly new and in great condition, so I'm not sure how the debris got into them unless some contaminated fuel got into the system at some point.  While I'm cautiously hopeful that we may have found and corrected the root cause, I don't understand how the debris would get all the way from the fuel bladder to the injectors since the fuel passes through fine screens (much much finer than the debris we've found clogging the injectors) on its way.  The only hypothesis I could see would be if very fine pieces made it through the screens and coagulated into larger pieces just before the injectors.  

 

If anyone has any other suggestions or ideas what to look out for I'm all ears.  In the meantime, its difficult to fly this thing outside gliding distance to an airport.

[N201MKTurbo]

So what you are saying is that the debris is coming from somewhere between the inlet screen in the servo and the injectors. This leaves the injector servo which could have deteriorating seals or diaphragms, the flow divider diaphragm. The hoses and a fuel flow sensor, if it is between the servo and flow divider.  If some thread sealant like “Fuel Lube” or Teflon tape were used it could be washing out and clogging the injectors.

[jnisley]

I have an M-20 turbos system, which is just a fancy version of the Rajay system. I have the Lycoming turbo injectors with the reference lines coming from the intercooler. The only filter is the intake air filter. The intake/compressor side of the system is always very clean except for a little oil downstream from the turbo. I have never had the problem you describe.

 

Is it possible your injector air hoses are deteriorated?

 

Where is the clog at the small fuel orifice or at the larger fuel/air orifice?

 

If it is at the small orifice it must be coming from the fuel system. If it is at the larger orifice it is probably coming through the air line.

Are you saying that the air that's introduced into the injectors doesn't actually mix with the fuel and enter the cylinder?

[jnisley]

Another thing to be aware of on this system, If you find that your EGTs are fluctuating on a cylinder during normal cruise it could be that the o-rings on you injectors are damaged or have deteriorated to the point of leaking air. (In my experience it took one hour of labor and less then a dollar in parts to fix it.)

[Piloto]

Try changing the hose between the fuel servo and the spider. There is no filter on this path and an old or low quality hose could be the culprit.

 

José

[carusoam]

Collect the bits get them to a microscope. The oil analysis people may be able to help with this task... Their labs are pretty capable of identifying what bits actually are actually made of...

As Jose' pointed out, fuel hoses have been known to degrade.

Check where filters and screens are in your fuel system. Fuel pick-up in the tanks, screen at the selector valve, filter in front of the FI system. If they are clean, then you know where it came from...

Unfortunately, You have a known issue that repeats itself. Keep Focusing on determining what it is.

Thinking out loud. trying to help out...

Best regards,

-a-

[eaglebkh]

This has happened to me twice in the first ~40 hours after engine OH...  Hasn't happened in the last year.  The first time, at least 1 cylinder went dead (no multi-probe EGT), the second time I had an EGT spike on #1 (with multi-probe EGT spike, EDM700 installed).  In both instances, my fuel injectors and screens were cleaned, but nothing was noted.

 

Never did happened before engine OH.  But I didn't have a multi-probe EGT, so it may have happened without my knowledge and never resulted in a dead cylinder.  Note, I don't have a turbo.

 

Additional data point: a don't have bladders.  I have been contemplating having bladders installed as a result of the injector clogs (tank sealant flaking off), but here I'm seeing Mooney's with bladders experiencing it, too.

[N201MKTurbo]

Are you saying that the air that's introduced into the injectors doesn't actually mix with the fuel and enter the cylinder?

 

No, it does. The fuel gets squirted out of the small orifice. The airflow through the injector atomizes the fuel stream as the fuel pases through the larger orifice.

 

The airflow is caused by the lower absolute pressure in the cylinder's intake port. In a NA engine the air comes through a small screen on the injector. In a Turbo engine the air comes from the turbo. In either case there should be the same air pressure differential across the injector as there is across the throttle plate.

[jnisley]

So the air actually doesn't mix with the fuel until the fuel is past the smaller orifice, it's been awhile since I looked at an injector?

[rissacher]

Thanks for the good inputs. We have already overhauled the fuel servo and the flow divider. We considered replacing the hose into the flow divider since its the only remaining component after a screen but it appears in good shape plus it's Teflon and doesn't look like anything that would produce black bits. Its really looking like the debris was from the fuel tanks but I still can't comprehend how it would make it to the injectors. We have about eliminated all the debris from the tanks so time will tell if that was the problem (ie more logged hours without a clog).

We have also thought about trying to get someone to analyze a piece but haven't been able to capture one yet. They are removed by blowing them out and then are never to be seen again.

[rissacher]

Another update.  Yesterday EGT was running high for cylinders 1 and 4.  Pulled the injector nozzles today to see obvious debris in only those two.  Blew out and captured the debris.  They were black in color and attracted to a magnet so they must be ferrous (have some iron in them).  Previously we thought the clog may have been rubber, gasket/sealer or lead but the magnet test should eliminate this.  

 

Unfortunately, we are still dumbfounded as to the source and how to eliminate the problem.  Similar material was also found in the gas tanks and the gascolator filter, but not the servo filter.  Although ferrous metal was found in the fuel bladders, how would it get all the way to a cylinder?  Is it possible the servo filter is getting bypassed (like it is designed to do if it gets clogged) even though it appears clean?  If the source is not the ferrous metal found in the fuel bladders, what else could be the source?  That is where else is the ferrous metal or a place for it to pool (besides the servo and flow divider since those were overhauled)?

[N601RX]

It may already be in your fuel that you are filling the plane with.

[kmyfm20s]

It may already be in your fuel that you are filling the plane with.

 

I was going to suggest a clean 5 gal cotainer and transfer fuel to your plane. Maybe even through a filter to see if it is in the fuel supply your getting your fuel from. Sound like a rusty old tank is the culprit.

[rissacher]

Its not in the fuel we are fueling from.  I can say this with confidence because other airplanes use the same fuel pump with no problems, and we have had the same problem fueling at other locations.  It may be that at some point before we owned the airplane that someone contaminated the fuel.  We have drained and cleaned the bladders, but there looks to be a little bit remaining.  Maybe we need to do several iterations of draining, cleaning and refilling (which we can do through a storage tank that has a filter so we don't have to dump the fuel each time).  

 

Still, even if there was something in the tanks, how is it getting to the injectors?  It has to get through at least 2 screens that I know of.  

[N601RX]

Are you removing the inspection panels and opening the bladders up to get all the fuel out.  Flushing gas through them isn't going to get everything out.