Fuel Injector Cleaning

Hi there. A friend of mine and I were discussing this morning, when and what with to clean fuel injector/primer nozzles on our Lycoming engines. Specifically what cleaning fluid, varsol or acetone? Whether to soak them for a period of time in the solution, then use a sonic cleaner or an old tooth brush? And how often should the injectors be cleaned and how do you determine when the injectors/nozzles need to be cleaned? I understand that fuel injector nozzles are different that primer nozzles on a normally aspirated engine, but would the cleaning procedures be the same?
Thanks for your input

Dave C
RV-7
C-GCPD

See Lycoming Service Instruction 1275C

I put my restrictors in a small beaker with acetone, about 3/4 inch deep, within an ultrasonic cleaner that has a water bath. Run for about 5 minutes. Blow dry and reinstall.

Same for the nozzles, but I do use a toothbrush to clean off the outside of any dirt.

Do NOT run a drill through them or you may change the orifice.

This is what I have done, YMMV. There are other solvents that have been recommended as safe. Do a google search, or VAF search.

And, if you have changed one or more injector sizes to anything different from stock, don’t mix them up!

I used to clean injectors - but followed various people who seem to know what they are talking about and stopped. 100LL by itself is a very good solvent. I do use some carb cleaner spray on the injector body screens.

Has worked well for a long time now.

Carl

Hoppes No. 9 Gun Cleaning Solvent is one of many choices.

This is the procedure I use. Looks like you have a number of choices for cleaning solvents. I used Hoppes No. 9 Gun Gleaning Solvent:

https://www.lycoming.com/sites/default/files/Cleaning Fuel Injector Nozzles.pdf

Next time you're bored, head to the man cave and make these two handy tools.

https://www.danhorton.net/Articles/0814_ShopTip_NozzleCleaning.pdf