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Cleaning Fuel Injectors


DonMuncy

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I frequently see where people are cleaning their fuel injectors. I have had clogged injectors (with a bit of debris) that had to be cleared/cleaned. But I don't think I have ever seen one that was obstructed with any kind of gunk that would require something to dissolve the stuff. It would seem that it would take a strange kind of material that would stick to the injector while being constantly washed by avgas. Are injector cleaners a "scam". What do you think?

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A few ideas...

1) I have used it in the automotive world.  The Chevron branded stuff added to fuel tank.  Oddly enough, it gives a noticeable change.  Done every 50kmi. Engine: 300hp IV350 (water cooled)

2) I have cleaned the intake tubes of the O360 where fuel is vaporized on its way to the intake valves.  With all the evaporation going on, the blue dye wants to deposit thickly on any surface.

3) As for our continuous fuel injectors... there is a vent hole allowing air entry, and a drain. It is possible that these devices can allow some blue deposits to form in the area of the fuel injector.

4) downstream of the injector where the fuel is spraying and evaporating may get some blue goo formation.

5) search for Hopp's gun cleaner. The preferred solvent for cleaning fuel injectors around here...

PP ideas only, not a mechanic...

Best regards,

-a-

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I don't think it's a scam, however you'll know when one is clogged. I no longer clean injectors just to clean injectors. It seems that about 60-70% of the time , after cleaning, a sliver of something gets knocked loose and ends up clogging the injector again. Having one clogged will get your full undivided attention!! I wouldn't wholesale this theory, but just don't clean them to clean them. 

-Matt

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11 hours ago, Hank said:

I've heard and read good things about Hoppe's #9, which also has other uses in the house. Always have a bottle around somewhere . . .

Yep...exactly what we do every annual.  All six get soaked in Hoppes for a couple hours, then rinsed with acetone, blown clear, inspected, and put into a ziplock for re installation with fresh o-rings.  Never had a glitch.

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I understand about the various ways and solvents for cleaning injectors, and I certainly understand about slivers, etc. that block injectors and have to be removed. But my point was, has anyone seen an injector that had a build-up of some material that needed to be dissolved before function could be restored.

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1 minute ago, Andy95W said:

I've seen what must amount to a slow but steady buildup of gas "varnish" that prevents a GAMI injector equipped engine not be able to run LOP until the injectors were cleaned.

Very interesting. I assume you are saying that over a period of time, the engine gets progressively rougher at the same fuel flow, or requires less leaning to run smooth, and then after using solvent on the injectors, the prior (smooth running at x gph) condition was restored.

At the risk of sounding like I am questioning your veracity (which I am not), can anyone think of any other explanation.

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FWIW, it was a customer's 1999 Beechcraft Bonanza (A36) with a Continental IO-550.  Came from the factory with GAMI injectors installed.  He would consistently complain of rough running when LOP as the airplane got closer and closer to its Annual Inspection.  We changed his oil every 30-50 hours, but wouldn't touch the injectors until the Annual.

We started cleaning his injectors every oil change and he stopped complaining.  BTW, I also did most of his Instrument training in that Bonanza and he was a very good pilot and not given to overreaction. 

That's the closest thing I've got to "evidence".  Probably not enough to hang your hat on, but enough to make you scratch your head.

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2 hours ago, DonMuncy said:

Very interesting. I assume you are saying that over a period of time, the engine gets progressively rougher at the same fuel flow, or requires less leaning to run smooth, and then after using solvent on the injectors, the prior (smooth running at x gph) condition was restored.

At the risk of sounding like I am questioning your veracity (which I am not), can anyone think of any other explanation.

For me its the EGT spreads. When they start to drift from each other is when I pull the inserts (never bother with pulling the entire injector).

 

-Robert

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Most or at least many injectors get partial blockages from installing them - piece of o-ring gets nicked or a little debris gets into the line when it's put back in place. This is an operation you want to do with the utmost cleanliness or you can do worse than you started.

That said, most injectors do need cleaning eventually, but NA engines shouldn't need it every annual. But turbo injectors are a different story being pressurized with UDP and will require significantly more maintenance just like pressurized mags.

As for maintaining them, this is best done by using a data driven approach - not on an arbitrary schedule but when warranted. The Savvy pilot knows their gami spreads and when they see the rankings from to lean to rich change then spots the injector(s) getting leaner; before the spread size changes significantly. I hope the difference is clear.

 

 

Sent from my iPhone using Tapatalk

 

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