Clogged injector

[FlyDave]

I was flying with a friend the other day and on run-up he had a rough running engine with high EGT and low CHT on one cylinder.

We looked in the JPI manual and it stated that he probably had a burned exhaust valve. He called his mechanic and the mechanic said "A burned exhaust valve? Bullshit!!! You have a clogged injector!".

So the mechanic came over with a can of carburetor cleaner, pulled the fuel line off the injector (injector still screwed into the head) and sprayed carburetor cleaner into the injector a few times until the fluid consistently went through the injector. He started the engine and it purred like a sleeping cat.

The mechanic said that the injectors typically get clogged by lead in the cylinder that gets sucked up into the injector when the engine gets shut down. I thought it came from the other end (fuel system) but he said that there are so many screens that there isn't much chance of something large enough to clog an injector getting through. So, if you're going to get a clogged injector, you'll probably get it right at start up and not once you been in the air for a few minutes.

So it sounds like this quick fix may save people a lot of time and money by not having to rely on an FBO somewhere in BF Egypt saying you need to top the entire engine. At a minimum, it can't hurt!

 

Dave

[PTK]

Same thing happened to me once on t/o at about 200 feet agl.

I can confirm the 4 cyl Lycoming is not quite as smooth on 3 as it is on 4!

The corn field ahead to the right was looking very enticing until it managed to suddenly clear-up on its own!

It was the longest minute of my life! Came back around and put it down without incident. Mechanic didn't feel it needed to be sprayed since it cleared-up.

[N201MKTurbo]

Dave, the indication you described sounds more like a fowled plug then a clogged injector. If you turn off one mag you will see all the EGTs go up and all the CHTs go down.

[FlyDave]

Dave, the indication you described sounds more like a fowled plug then a clogged injector. If you turn off one mag you will see all the EGTs go up and all the CHTs go down.

All EGT's rose normally on mag check except the offending cylinder  - no change in EGT or CHT.

[Bob - S50]

I was flying with a friend the other day and on run-up he had a rough running engine with high EGT and low CHT on one cylinder.

We looked in the JPI manual and it stated that he probably had a burned exhaust valve. He called his mechanic and the mechanic said "A burned exhaust valve? Bullshit!!! You have a clogged injector!".

So the mechanic came over with a can of carburetor cleaner, pulled the fuel line off the injector (injector still screwed into the head) and sprayed carburetor cleaner into the injector a few times until the fluid consistently went through the injector. He started the engine and it purred like a sleeping cat.

The mechanic said that the injectors typically get clogged by lead in the cylinder that gets sucked up into the injector when the engine gets shut down. I thought it came from the other end (fuel system) but he said that there are so many screens that there isn't much chance of something large enough to clog an injector getting through. So, if you're going to get a clogged injector, you'll probably get it right at start up and not once you been in the air for a few minutes.

So it sounds like this quick fix may save people a lot of time and money by not having to rely on an FBO somewhere in BF Egypt saying you need to top the entire engine. At a minimum, it can't hurt!

 

Dave

We had similar indications and it was an injector too. Ours was in fact crud from the fuel side.

 

Bob

[Super Dave]

All EGT's rose normally on mag check except the offending cylinder  - no change in EGT or CHT.

This is exactly what a fouled/bad spark plug would look like on one magneto at run up.

For example, if the top plug in cylinder #3 were fouled, and you select the mag that fires the bottom plug during your run up, you will see a rise in all EGTs except #3, because #3 was already running on only one plug. Now, when you select the mag that fires the top plug (the fouled one) in #3, the cylinder will have no spark because one is fouled and the other is being switched off by you. EGT for #3 will go cold, and the engine will run very rough

[FlyDave]

There was no change in cylinder #5 CHT or EGT on both, mag 1 or mag 2 check. So I don't think this was a plug (fowled or bad) or mag issue.

[Seth]

I had two incidents of clogged injectors / debris in the injectors in my former F model 4 cylinder engine.  Once in an IFR / IMC flight from Pittsburgh to Maryland, and once from Maryland to Tampa.

 

One time it looked like small compacted dirt in the injector, the second one looked like paint chip slivers. 

 

Both times the engine ran rough, and I had to run full rich as the cylinder was running lean from the blockage.  I did not have an engine monitor in that aircraft.

 

Glad you were able to simply clean it an move on.

 

-Seth

[Bill_Pyles]

I departed ABE last Sat with my brother who had never flown with me and and about 1000 feet AGL, the engine went rough and felt like it was going to shake itself loose, so I did all the usual stuff like switch tanks, full rich, mage check etc and of course the roughness continued, so I returned to the field and landed.  I did a run-up and the #4 cylinder was cold for EGT and CHT so I cleaned out the injector and it ran fine and my trusting brother even went with me on the test flight, which was fine.  Over the next three days I flew back to AZ with no issues.

 

The annoying thing is that this is the third time I have had a clogged injector in about 18 months.  One of the other times I aborted the take-off on the ground roll and the other time I had just gotten into the air, and landed on the runway when the engine started running roughly.

 

I am wondering if there is something in the system that is occasionally shedding debris the clogs the injector.  I had the tanks resealed by Weep No More three years ago when I bought the plane, so the tanks were thoroughly cleaned at that time.  Usually the debris is black, but this time there was some yellowish stuff that might have been plastic.

 

Any ideas?

[FloridaMan]

I had the same thing last week. There was a piece of metal in one of my injectors. It stumbled between 2200 and 2400 RPM. EGT was "0" on the offending cylinder when stumbling at 2400 RPM. When I backed down to 1900 RPM, EGT was very high on that cylinder. It behaved the same on L/R and Both mags; switching to a single mag would raise EGT on that cylinder even more. 

 

The logic is that the cylinder with the clogged injector will run excessively lean; at the same time, all other cylinders will get extra fuel and run excessively rich. 

[aaronk25]

So here is a question: since a clogged nozzle could debatably happen with great probability, if a nozzel were to become clogged and I was 1/2 way over the Gulf of Mexico 280n.m. From shore would the plane maintain altitude?

Or would I be fish food?

[mooniac15u]

So here is a question: since a clogged nozzle could debatably happen with great probability, if a nozzel were to become clogged and I was 1/2 way over the Gulf of Mexico 280n.m. From shore would the plane maintain altitude?

Or would I be fish food?

 

It depends on the degree to which the nozzle is blocked.  I have had a clogged injector that just resulted in increased EGT for that cylinder and an inability to lean very much.  Otherwise the engine performed well.  In a case like that fuel burn might become a bigger issue.

[jetdriven]

So here is a question: since a clogged nozzle could debatably happen with great probability, if a nozzel were to become clogged and I was 1/2 way over the Gulf of Mexico 280n.m. From shore would the plane maintain altitude?

Or would I be fish food?

I don't know how probabability it is to happen but I have read that most clogged injectors are the result of someone cleaning them and getting trash in the fuel system that way. But regardless, the J will make way at 40% power and I think it could deliver that on 3 cylinders. I don't know of any other planes that can.

[fantom]

Most times injectors can be left alone since they already have a regular good rinsing. As Byron says most injector problems are induced by too much careless fiddling.

[outermarker]

Besides the removal and cleaning of injectors, can MMO be used on occasion as a preventative measure? If not MMO, are there any other injector cleaners that won’t harm the fuel tank sealant which can be used?

[ArtVandelay]

FWIW, my clogged injector was after maintenance and 5 weeks of inactivity, found it before I even did the run up

[carusoam]

Usually, it is a remove, clean, and replace activity... Checking the flow balance of all when done...(glass jar test)

Too much fear in ruining sealents and seals to experiment adding something into the fuel...

Best regards,

-a-

[Seth]

So here is a question: since a clogged nozzle could debatably happen with great probability, if a nozzel were to become clogged and I was 1/2 way over the Gulf of Mexico 280n.m. From shore would the plane maintain altitude?

Or would I be fish food?

As mentioned, it depends. Both times it happened to me I simply couldn't lean, and when I when I pulled back power to far my engine ran rough.

As a pilot I respect once said to me, if you ever find yourself as a test pilot, meaning you feel the airplane is trying to kill you, do only what is necessary to maintain control. Make the envelope so small that you keep control until after landing.

Both times I did not lean once I determined that caused roughness and kept power and RPM where the engine ran smooth at a good temperature and left it there until the landing patten at the airport when I knew I could glide it in and then reduced power to rough running.

It will affect your speed, mixture, and range, this ensure you land at the closest next destination over be Gulf.

-Seth

[Piloto]

Clogged injectors are also caused by debris from old rubber hoses. Specially if the incident repeat again. The hose between the fuel servo and the spider is the likely hose since there is no filter in between. Usually fuel sediment clogging is gradual causing gradual increase in EGT.

 

José

[flyboy0681]

I may have experienced a clogged injector last week. 15 minutes into the flight it started running incredibly rough and the shaking was very un-nerving. It cleared up after 45 seconds but I headed back to the airport anyway. The shop on the field examined the plugs and cleaned the nozzles and gave it a clean bill of health. I flew home the next day without any further incident. 

 

Once home I downloaded the JPI data and here is what it shows. Any guesses?

 

 

[N201MKTurbo]

Could be a valve stuck open too. Whatever it was it got over it.

[LANCECASPER]

On 4/1/2014 at 1:03 AM, FlyDave said:

I was flying with a friend the other day and on run-up he had a rough running engine with high EGT and low CHT on one cylinder.

We looked in the JPI manual and it stated that he probably had a burned exhaust valve. He called his mechanic and the mechanic said "A burned exhaust valve? Bullshit!!! You have a clogged injector!".

So the mechanic came over with a can of carburetor cleaner, pulled the fuel line off the injector (injector still screwed into the head) and sprayed carburetor cleaner into the injector a few times until the fluid consistently went through the injector. He started the engine and it purred like a sleeping cat.

The mechanic said that the injectors typically get clogged by lead in the cylinder that gets sucked up into the injector when the engine gets shut down. I thought it came from the other end (fuel system) but he said that there are so many screens that there isn't much chance of something large enough to clog an injector getting through. So, if you're going to get a clogged injector, you'll probably get it right at start up and not once you been in the air for a few minutes.

So it sounds like this quick fix may save people a lot of time and money by not having to rely on an FBO somewhere in BF Egypt saying you need to top the entire engine. At a minimum, it can't hurt!

 

Dave

Reviving an old thread. Sunday I went up and less than a minute after take off my TIT was very high at full rich and my #4 cylinder was high - definitely caught my attention so I landed. @kortopates looked at my JPI data and it looked like a clogged injector but the data looked like it might possibly have cleared itself out after I landed. but I wasn't completely convinced that it had cleared itself since I couldn't get the TIT below 1100 before shutdown, when it's usually in the high 800's. 

This morning after reading @FlyDave 's post. I pulled the line away from each injector and with red straw that comes with the carb cleaner got a couple of good shots in each of the 6 injectors. I torqued the lines back on the injectors and let it sit for over an hour. I went out and ran it up and all the temps look great and it runs very smoothly now. The TIT at shutdown was back down where it normally is at 870.

 

Thanks @kortopates and @FlyDave.

[FlyDave]

Lance,

I'm glad it worked out and you found my post useful!

Fly safe!

Dave

[Marauder]

Lance,
I'm glad it worked out and you found my post useful!
Fly safe!
Dave

He’s alive! I thought perhaps Joe Walsh retired and the Eagles picked you up. I still thinking about those “sleeping” photos we shared on our way back from Oshkosh.


Sent from my iPad using Tapatalk Pro

[FlyDave]

14 hours ago, Marauder said:

 

He’s alive! I thought perhaps Joe Walsh retired and the Eagles picked you up. I still thinking about those “sleeping” photos we shared on our way back from Oshkosh.


Sent from my iPad using Tapatalk Pro

 

Yessir! And livin' life large . Not as large as Joe Walsh, but I don't have his looks either .

Not flying as much as I used to. And not really current on anything except day flight - and that ain't much .

Let me know if you make it out to the Bay Area.