Persistant Clogged Injectors..Turbo e

[rissacher]

Yes, bladders have been opened, and scrubbed.  Unfortunately, this got rid of 98% of the debris, but the remaining 2% is still noticeable.  Still... Anyone have thoughts on how that crap is getting from bladder through multiple screens to the injectors?

[rissacher]

So the question now is do we essentially replace the entire fuel system end-to-end (hoses, pumps, servo, spider, etc.) or can someone recommend some troubleshooting tips?  On one hand I would say finding the same metal bits attracted to a magnet (i.e. not aluminum) in the injector that's in the bladders means that the source was in the bladders... but on the other, how could even one piece of debris possibly make it through 3 screens to the injector?

[larryb]

So the question now is do we essentially replace the entire fuel system end-to-end (hoses, pumps, servo, spider, etc.) or can someone recommend some troubleshooting tips? On one hand I would say finding the same metal bits attracted to a magnet (i.e. not aluminum) in the injector that's in the bladders means that the source was in the bladders... but on the other, how could even one piece of debris possibly make it through 3 screens to the injector?

Probably because the debris is smaller than the screen mesh. I wish we had true filters and not screens in our planes. Do you find any debris caught in the screens?

[rissacher]

Found some caught in the gascolator screen, but not the servo screen. 

 

The debris is definitely bigger than the screens (found in injectors and in bladders).  The only thing I could figure is that the debris is getting around the gascolator screen and maybe the servo screen is getting bypassed incorrectly.  There may be additional screens that I'm not aware of as well.

[tomn]

Just thinking outside the box here - have any of the metal fuel lines been replaced - possibly with the wrong type of tubing?

I was going to suggest replacing the fuel lines until you mentioned them being magnetic. I had the fuel pressure guage needle bouncing that was caused by small hose debris in the back of the gauge. Cleaned it out and replaced the hose feeding the gauge fixed it.

[rissacher]

I haven't been able to find any fuel lines that are made of a magnetically attracted substance minus some fittings, but thanks for the thought.

[carusoam]

Can you verify that you no longer have ordinary "mild" steel fill necks on your tanks?

Older tanks (my 65C) were originally supplied with this low cost oddity.

The newer versions are SS.

Typically the older ones rust slowly over 40 years and drop small flecks that are often found in the fuel screen/selector valve. There should be some kind of sock on the fuel pick-up line. As the first two lines of defense.

I offer this thought because I had experienced unexplained tiny rust specks in my fuel sampling cup in my previous plane.

Best regards,

-a-

[rissacher]

That's very interesting... I will have to check on that.  The specs aren't "rusty" looking, but I'm up for replacing anything that shouldn't be there (and the gas caps are currently very difficult to open anyway).

 

I don't believe the fuel lines have a sock on them.  There's a metal screen, but what you describe sounds like some sort of fabric.

 

Thanks for the advice.

[jetdriven]

Our bladder filler rings are stainless. How about taking 15 gallons of Jet A (much less risk of fire), fill tank on one side, slosh wing around really hard to agitate and suspend the trash, then drain by unthreading the quick drain in the wing and draining into a grounded metal can. ground the can, airplane, and the ground together.

It drains out fast in about ten mins. Strain the Jet A through a paint strainer as you refill the tank, slosh, drain, repeat a few times until all the debris is flushed out. The bladders may trap some residual Jet A in the low points, so be sure to refill with 5 gallons of 100LL, slosh, then drain and discard that, or do as I do with my stale outboard 2-stroke gas, put it in your Honda Accord and drive on.

Note, to check for residual Jet A contamination, drain a half ounce onto a paper towel and let air dry. if it is contaminated it will still feel greasy or wet after a few mins. Gasoline evaporates completely dry.

[rissacher]

Good thought on the Jet A for flushing.  The tanks have been a flushed a few times with the 100LL.  Initially it was just a drain and clean, but we discovered it may take a few iterations.  My A&P has a large fuel tank with a filter so we don't have to waste too much fuel.  My thinking was that its probably best to completely fill the bladders to reach all the surfaces.  This may do the trick, as long as something else isn't shedding metal.  The fuel caps are a good thought that I haven't considered so I'm checking to see whether they are original equipment or have been replaced.  The only surface in the bladder that I found that was attracted to a magnet was the fuel level sender float arm but I don't recall if I checked the cap with a magnet.