Very Rough Running Engine

[aschardt]

Today I tried to take my sister and soon to be brother in law for thier first GA flight.   Got the plane out, started normally, after warm up, I ran it up to 2000 rpm and checked mags, prop, etc per checklist, no problems.  Got out on the runway, normal throttle up and about 2200 rpm the engine just "fell apart".  Ran terribly rough, RPM couldn't get abot 2300 or so, MP wouldn't go over 23 or so.  (1633' elevation)  Obviously aborted the takeoff and cycled everything I could think of 5 times or more.  Mags checked out, fuel pumps good, fuel pressure good, oil pressure good, temps good except for a slightly higher #4 cylinder EGT, everything else normal!?!

The engine has 1050 hours SMOH and the plane is 8 hours out of an annual which pulled the #4 jug for a broken ring.  Last flown for 2 hours 3 weeks ago, ran smooth, no indication of any problems.  It has been hangered since then. No water in the fuel, sumped fuel, looks normal.  Engine runs GAMI's.  Throttle back to under 2000 and it runs completely normally. 

I've never had engine issues before, how can a $30,000 engine decide not to run one day?!!!  Anyone have a similar issue?  Any ideas.  The A&P will come to check it out next week, but this is frustrating. 

Thanks!

Aaron

 

 

[MooneyMitch]

In my humble opinion, and from my long ago experience very similar to yours, your issue has the tone of some fuel contamination/blockage in the Bendix RSA fuel injector.   I suffered the exact run up, mag check and full power symptons as you have described.   I hope this helps you.

[aschardt]

Hmmm.  At that last annual they did remove some sealant in the tank to repair a slight leak.  The tank was flushed, but could be some sort of filter blockage perhaps.  I assume there is a filter prior to the injector manifold?  Is this easy to check?

[Immelman]

You mentioned only 23" MP. That sounds like an induction issue to me, not necessarily fuel injection.

[MooneyMitch]

Please keep us posted if you would.  We are curious of course.

[Lood]

I had a similar issue about a year ago on my M20F - mine included a lot of backfiring as well. After a lot of trouble shooting which included the spark plugs and injectors, it turned out to be a tiny spec of dust or whatever that got itself into the fuel divider. We only found that out after swopping the deviders. The AMO found the culprit under a magnifying glass and removed it after which my problem were over. Good luck.

[aschardt]

Well guys, we found the culprit tonight.  Pulled the fuel filter and it was clean, no debris at all.  Pulled the injectors and low and behold the #2 injector was mostly clogged with something.  Had to blow it out with an air compressor so we never got to see what it was but since it was post filter it's not likely to be a piece of tank sealant.  My best guess is perhaps a piece of rubber from the short hoses that feed the air to the injectors.  The rubber looks good and does not appear to be breaking down, but perhaps it was just a piece that was hanging on and for whatever reason decieded to let loose. Anyway, we ground ran it and it's back to it's old self, no hiccups at all. 

Thanks for the input everyone! 

-Aaron

[Seth]

Funny, thinking about it, a very similar problem happened to me, but it was in flight about five months ago, not on take off, when I leveled off at 7,000 feet after departure from Pittsburg (KPIT).  Some loud popping and decreased groundspeed (with a tailwind in fact).  I didn't want to descendas I was in pure IMC, so I reported partial engine power loss, increased the mixture, and found that I couldn't climb more than about two hundred feet per minute.  I saw that everything was stabilized, no oil pressure, temperature, or any indications of any issue except for popping if I tried to lean the mixture and partial loss of power.  I made sure I knew where the closest airport was at all times.  I did not want to decend should I lose the engine and not break out of the cloud layer (I entered it at about 700 feet AGL), so I stayed at 7,000.  And when I broke out of IMC I was already on the fringe of the DC class B airspace (IAD, BWI, DCA, SFRA).  I advised ATC of the issue as I descended, and made it back to my home airport.  In the pattern, my engine backfired and was popping very loudly as I pulled back the power.  I was afraid I was going to lose the engine, so I cut the base leg early, and used the speed brakes (yes, my F model had speed breaks when I purchased it) to ensure I didn't float down the runway.

It ended up as the SAME issues as you - dirt in the #2 fuel injector.  It cleaned right out and the plane has not had a hiccup since (except popping noises on the ground when warm - we've talked about that before - the 67F's are known for that).  It ran smoothly on the ground, but upon full power on takeoff run (the problem would not reproduce itself on the ground) the same symptoms as you appeared and we aborted the takeoff (really planned as a high speed taxi anyway).

Sorry I didn't read this earlier as I would have suggested that.

[The-sky-captain]

Is it standard annual procedure the clean the injectors?

[Seth]

I think so - pure speculation.  I know I did at my last annual as I was trying to figure out the ground popping that is simply common with the 67F and a few other models.  For me it had been about a hundred hours since the annual (flew exactly 201.4 hours in the last 12 months as of today, December fools day).  It's amazing how much more you fly with your instrument rating.

[The-sky-captain]

I agree about flying more with the IR, I just got mine a few months ago and it has really opened up alot of days that were off limits before. i too am right at 200 hrs in the last 12 months. It never gets old:)

[KSMooniac]

The Advanced Pilot Seminar guys preach that fuel injectors should NOT be cleaned regularly, since they're in a solvent bath (fuel) all the time.  They should only be cleaned "on condition" which is recognized with an engine monitor reading or roughness in flight.  Flying LOP will expose such a malady very quickly too, whereas ROP might mask the problem.  They said the most common debris found in the injectors is red lint from shop rags...from mechanics cleaning them.    I've cleaned mine once in almost 3 years of ownership, and only because I had them all out for cylinder work.

[aschardt]

Hey everyone.  We'll it happened again!  nearly 20 hours after the first episode, I suffered an exact repeat of the first clogged injector, only this time I knew exactly what the problem was.  Put it in the shop and it was not only the exact same cause, but the same injector!  Ok, now this is wierd.  This mechanic (different one than first time) thought it was coming through the induction line.  What could be breaking down to cause this?  I'm planning a long flight in three weeks and want to get this one fixed now!  Any ideas? We're going to remove the induction lines to the GAMI's and let them sit in solvent for a while.  Maybe someone used a sealant at one time?  ???

[MooneyMitch]

My thoughts for you.  The fuel hose to the injector servo and/or the fuel hose from the injector servo to the flow divider?  Are these possibly breaking down inside and the material is reaching your injector nozzle?  A good friend of mine spent many hours attempting to discover symptoms similar to yours, only to find that the clogging material was indeed coming from one of those hoses.

He was told that these rubber hoses begin to breakdown internally after about 5 years.  I've not heard of this and it has never been a problem for me.   I realize we are to replace engine hoses 7-10 years, but I am not aware it is because of internal issues.  I will post this question on the MAPA forum as LASAR, Top Gun and Don Maxwell chime in ocassionally. 

[KB68M20F]

You might consider installing a JPI engine analyzer which is very helpful in troubleshooting this type of problem.  I had the same problem and could tell immediately which cylinder it was by the #4 EGT bar which shot up above all the rest.

[Seth]

UPDATE - As I pulled back the power and began my decent into Tampa on Friday, my engine started running REALLY rough, vibrated badly, and started popping and banging just as it did two years ago and similar to your engine on takeoff when you began this thread. 

I let ATC know immediately that I had a rough running engine.  I was able to smooth it out somewhat by keeping 2500 RPMs, full rich mixture, and very slowly manipulating the manifold pressure.  As I pulled power on landing, I thought it might have quit on me.  Tampa approach was great in giving me assistance and allowing me to stay higher longer, until I was sure I could glide to one of many fields. 

One I landed, I had a mechnic on the field look over the engine for me, and as soon as we together took of the cowl, again, it was obvious that fuel was not properly dispensing from one of the injectors.  A flush of the fuel injector lines and boom - smooth running engine.  This time it wasn't a piece of dirt, but what looked like paint chips, or slivers of paint - no clue how they got in there.

Has this type of event happened to anyone else except for Aaron?  It's now happened to me twice - once on Thursday, and once in Julyish of 2009. 

Thanks,

-Seth

[Ron McBride]

On my 69F, when they installed my EDM700, they used teflon tape. The tape is not compatible with fuel. It slowly came apart, clogged injectors and eventually the Fuel controller went TU. Whenit was rough, you would think that the pistons were swapping holes.  Rebuilt Fuel controller and distribution block and reclean the injectors for the ?? time, All is very well.

Ron

[aschardt]

Sorry to hear it Seth, nothing worse than having an engine problem recur and not be absolutely sure what the issue is.  For what it's worth, after the second episode my mechanic put a filter on the upper deck reference air lines and I havn't had an issue since (knock on wood).  $25 in parts, he kind of made it up as he went.  If you want PM me and i'll get you his name and he can maybe talk you through what he did.  I figure it couldnt hurt.   Good luck.  -Aaron