AeroVee - starting and running issues

[Rynoth]

Popping into this old thread, as it provided me with very useful information today. I had cleaned my aeroinjector this weekend (had some sticking issues due to old 100LL and not much run time over a few years) and re-inserted the needle, but I did not visually verify the needle's position after setting the lock screw. My engine was performing very poorly after cleaning the carb, especially at low power settings, constantly dying. I had re-inserted the needle by counting the revolutions of the set screw when I removed/reinstalled it.

However, after removing the air filter, marking the needle, then removing the needle, I found that it had been set far too lean. I then slightly deformed the threads in the screw for the needle so the screw could not freely turn when setting the set-screw. I marked the needle per the Aeroconversions instructions, and re-inserted it, visually verified it's position with the air filter removed, attached the air filter and had an excellent test run. Thanks for this thread!

TL:dr: Always visually verify the position of the needle when re-inserting it (removing the air filter is an easy way to do this), and by deforming the threads slightly on the screw for the needle, I can now be confident that the needle's position will not vary while setting the set-screw.

[lutorm]

Rather than deforming the screw, this seems like a good application of Loctite "purple" 222MS. This is a low-strength thread locker meant for things like set screws that allows repositioning while still increasing the friction enough to not make them move on their own.

I found that, if you have a fuel flow meter, a good check for making sure the screw is back to its original setting is to verify full-throttle fuel flow.

[Jgibson]

"Old 100LL". ??

Please explain. Old meaning contaminated? With dirt? Water?
As an experiment, I ran 100ll successfully that had sat for 15 YEARS in an abandoned plane. Started and ran just fine. But there was no water or dirt in there.

[Spinnetti]

"Old 100LL". ??

Please explain. Old meaning contaminated? With dirt? Water?
As an experiment, I ran 100ll successfully that had sat for 15 YEARS in an abandoned plane. Started and ran just fine. But there was no water or dirt in there.

Unless its a full tank and dang near perfectly sealed, the lighter aromatics evaporate off and the rest gets sludgy... We had antique cars that sat for decades and ran when we got them, but I'd sure never fly behind that! I'd flush the old stuff and put in some fresh and use the old fuel in the lawn mower.

[lutorm]

100LL may not go old like ethanol gasoline does, but it still leaves residue when it evaporates. I thought he meant that there was residue on the needle or the orifice from evaporated gasoline that made it sticky.

[Rynoth]

100LL may not go old like ethanol gasoline does, but it still leaves residue when it evaporates. I thought he meant that there was residue on the needle or the orifice from evaporated gasoline that made it sticky.

I'll upload a photo soon, but yes it was a waxy blue residue (the dye maybe?) that thoroughly coated the inside of the injector. Cleaned/wiped off easily with acetone. The engine ran fine earlier that day, but I hadn't run it in a month or so and it was a very cold day. It almost seems like it got soft with running, then firmed back up a couple hours after shutdown to the point that it bent my throttle cable when i went to close the throttle at the end of my day at the shop (had bumped it open at some point.)

[SonexN76ET]

Ryan,

I am concerned about your post about the fuel residue you mentioned being soft and then getting hard and this has stuck in my mind since you posted it. Today, doing some unrelated research I came across a CASA safety bulletin stating that symptoms such as you described with 100 LL are often due to incompatible fuel hose and that often this residue may be the byproducts of the compounds in the fuel hose breaking down. As a safety measure may I suggest you check into this as well?

Thanks,

Jake

[Rynoth]

Jake, thanks, I will indeed look into that. My recollection is my fuel hose running from my gascolator to Aeroinjector was made from extra length that came with my Aerovee Turbo kit for the oil system. I have however noticed this kind of waxy residue around the drain of my gascolator (after the plane sits awhile) as well, which is upstream of any fuel hose.

As promised, here's a pic of the inside of my Aeroinjector before cleaning it.



It was soft/waxy, but not hard enough to chip, just smear. In case it's not clear from the photo, the residue was very much blue, like the dye in 100LL. It wasn't hard to remove with a rag and some acetone.

I inspected my gascolator as well and the inside of it was clean, including the filter. The engine was running fine, and I never would have had a clue about this residue if it hadn't made the carb stick enough to make my throttle cable kink. I have since drained all fuel in the tank and replaced with fresh fuel.

[kmacht]

I have had a similar blues waxy residue next to a very slow leaking oops fitting. Nothing there but the plastic gas tank and the aluminum oops fitting. It wiped off with a little rubbing from a rag.

Keith

[peter anson]

Crikey, Ryan, that's a lot of gunk. When I have bought hose from car parts shops it is specifically labelled for "FUEL" or "OIL", implying different materials for the different fluids and not interchangeable.

Peter