help Persistently Clogged Injector Nozzles

[afward]

This is killing my IA and I...  My IO-360-A1A seems to clog injector nozzles every couple flights.  We pulled the screen after the fuel pump and cleaned it, overhauled the fuel divider, replaced the throttle body & replaced the fuel line to the flow divider, and cleaned the flow divider.  Flew it yesterday for about 20 minutes, and today all the nozzles were blocked (only one even had light showing through).  We're at wit's end...

A few details:

The grit in the inline screen was lighter colored while the "globs" in the nozzles and flow divider have all been very dark.

The nozzles feel "sticky" when removed for cleaning.

Anti-seize was used on the nozzles after the first cleaning, but has since been cleaned out of the ports' threads.

The old throttle body had rust in the inlet chamber and on the filter, and the spring was stuck in some unidentified "gunk" at the bottom.  We didn't know how bad the rust was so we replaced it outright.

The only parts on the metered side of the throttle body that haven't been cleaned or replaced/overhauled are the lines from the divider to the nozzles.  Those are next for cleaning if cleaning all the nozzles doesn't work today.

Thoughts?  Ideas?

[takair]

What is the condition of your tanks?  When you sump at the three points, do you get crud?  If the sealant is breaking down it can get past your screens.  You can try to sump more, but this could indicate tank work is needed.  Oh, also, age and condition of fuel lines....

[afward]

Y'know, I thought of that...  There for a little while I was getting some crud out, but looking at the JPI data I think the problem started before then and I've not gotten any crud out in the last few months...  There is a seep in one tank and a slow drip in the other when more than half full.

I am scheduled with Weep-No-More, but it's gonna be a while and I'd really like to have a reliable plane before then (next year)...

[EricJ]

There are two screens between the fuel pump and the nozzles:   the one right at the electric boost fuel pump (which doesn't exist on all airplanes, I think), and the finger filter in the fuel servo.   Both need to be checked.    When checking the one in the fuel servo, remove it from the feed line side so that it doesn't leave a trail of crap inside the servo when being removed.

If the hose from the servo to the divider is deteriorating that can be problematic because it is after all of the screens.

FWIW, when I bought my airplane all of this stuff was problematic.   I had a LOT of rust and crap inside the finger filter and was getting occasional injector clogs.  My servo eventually failed at an inopportune moment.    It got overhauled and the repair station sent all the old internal parts back with it and a note that said it was "full of grit".  One of the diaphragms had a clear indication that it had been partially full of water at some point.

I later went to a presentation by Precision Airmotive on the RSA fuel servos and they mentioned this, that on Mooneys they sometimes get water in them and it leaves a scale mark across the diaphragm. 

I don't know how the water gets in there, but one possible path is through the ram air metering inlets if you fly in rain.   Since Mooneys are some of the few airplanes that employ ram air inlets where the rain can get to the ram air inlets on the servo, this might be a thing.  I have a J so I just deleted the ram air inlet in the cowl and bid good riddance to it.

Anyway, be careful because my servo failed after some bad behavior and a few clogging events, which I'm sure you're aware are pretty much not fun by themselves.

Edited January 29, 2021 by EricJ

[RLCarter]

If it’s that bad I would start at the tanks and work down stream, and replace all the rubber hoses along the way

[PT20J]

The filter after the boost pump is only on certain installations with Dukes pumps -- see attached SB20-222B.

The hose to the fuel pressure transducer attaches to the servo after the finger screen and I would check that also.

Skip

SBM20-222B.pdf

[afward]

2 hours ago, EricJ said:

 I had a LOT of rust and crap inside the finger filter and was getting occasional injector clogs.

That... sounds waaay too familiar.  Now I'm even more glad we replaced the whole servo!  I will note the new one took to idling at ~700 rpm quite easily and it actually shuts down properly when I pull the mixture.  Bonus?

I just snagged the last reseal slot at Wet Wingologists for February, so I'll have a PIREP on them in a bit over a month...  If I'm still having problems after that I'll be off to Maxwell to get the remaining hoses old replaced.

[carusoam]

Pictures are important...

Color, size, hardness...

Even if you can’t recognize what it is... somebody around here probably has a similar picture... 

All rubber components are suspect.... review where all the rubber parts are in your fuel system starting at the tanks and working towards the FIs

Some 60s fuel tanks still have a mild steel fuel neck...  if you are seeing rust particles in your sumps... get a look at the back side of the fuel neck...

 

Might be good to include The good doctor in the conversation...  @M20Doc

PP thoughts only, not a mechanic or a great communicator...

Best regards,

-a-

[afward]

Haha, thanks Anthony!  I don't have any pictures, but my IA is certain the dark globs are NOT from rubber hoses.  Per his assessment, it looks just like one would expect sealant to look.  Basically, aside from the rust in the fuel servo, all the contaminant we've found has been a very dark grey blobs, no large particles (looks like it could be very small particles in solution), and very sticky.  In the ultrasonic cleaner it comes out as just a dark cloud.

[Guest]

It’s hard to imagine that something Is getting past the boost pump screen, the gascolator screen and the finger screen in the servo.  I’d be starting at the nozzles and working backwards.

How clean is the 1/2” socket being used to install the injectors?  Cleanliness in next to Godliness.

Clarence

[MB65E]

I’ve had bad gas before. Noticeable decrease in performance. Proved to the vendor their fuel was junk by pumping gas through a microfiber rag. After only about a min of pumping fuel the rag was discolored. You could not visually see the sediment in the fuel sample alone. Not sure of what the fuel servo looked like as that was the last show of the year and the engine was overhauled. 

My theory of clogged lycoming injectors may be flawed, but I have never had a clogged injector during normal operations. It was either maintenance induced or something was bad. 
-Matt

[Bartman]

When we did my engine rebuild and install immediately on the first start had a problem with injector clogging. After cleaning the injectors and having the same thing happen again we quickly traced it to a contaminated flow divider. During the rebuild we had installed all new hoses including those from the RSA to the flow transducer and to the flow divider. The shop said the divider was full of contamination and I think it was from the new fuel hoses themselves from the cutting process, but it could be contamination at the time of hose installation at several connections and fittings. 
 

I did not install the hoses the first time, but I did the second time around I personally did the install of all fuel hoses, fittings, fuel transducer, the flow divider, metal fuel lines and new clamps and the injectors after the flow divider was returned from the shop. I can tell you I was METICULOUS in cleanliness of everything including my hands, fingers, finger nails, the work area, the tools, and kept the hangar doors closed. I used clean 100LL to clean and scrub the tools including repeatedly brushing and flushing the inside and outside of the brand new 1/2 inch socket used for installation of the injectors. 

[David Lloyd]

Just cause they're new hoses, doesn't mean they're clean hoses.

Our company made hydraulic hose assemblies. Cut the hose, crimp the fittings, ship 'em.  Never saw any of our competition do any different.  Using our own assemblies in our fabrication shop building hydraulic power units, our shop guys would clean and flush everything before assembly.  If in doubt, ask.

[afward]

18 hours ago, M20Doc said:

How clean is the 1/2” socket being used to install the injectors?  Cleanliness in next to Godliness.

The socket itself is visibly clean (at least it was last time; I'm the one that put them back in, under supervision of course). The ports did have what looked like anti-seize around them, which I cleaned as best I could.

Related to that, the next flight was to Wet-Wingologists...  Everything was good, except it was touchy to lean: setting a target LOP took some back and forth before it settled just below peak with a 25F spread.

I'll probably ask for the flow divider, steel lines, nozzles, and ports to be cleaned while the tanks are being resealed

[Browncbr1]

Try doing the Dixie cup routine continuously while switching the fuel selector back and forth.  Sometimes over a long period of time, junk collects in the fuel selector valve

[DEGWS]

I had a stumbling engine a few minutes after departure at 3000ft two years ago. One injector was clogged. First time I only cleaned the injector and all works well for a few flights. Then I recognized a very high EGT on the EDM on one cylinder. Again one injector clogged. This time I also removed the fuel filter from the fuel servo. A lot of rust. Seems there was some water or something else in the servo.

Since then I checked the filter every 50hrs. Until now it has been clean so I will change to inspect it every 100hrs.

So always carefully check this. Definetly no fun with a nearly totally clogged injector!

[carusoam]

Great filter pic DEGWS!
 

Thanks for sharing it.

That is eye opening!

See if @afward is stopping by...

Best regards,

-a-

[David Lloyd]

That inlet screen looks like it wasn't checked in many years. 

[afward]

Thanks Anthony!  That's a crazy picture...  Far worse than mine was.  That said, it's amazing how much better the engine runs with the replacement fuel servo (and a fresh cleaning of the nozzles ); Starts right up, idles smoothly & at much lower RPM, builds good power more smoothly, and shuts down cleanly.

I've got a bit over a month before the tanks are done...  I'll report back on this thread with results after I've had the plane back for a few flights.