Do not remove the pump!!!!!!!!!!!!! while it looks easy with four bolts the backing plate is the back of the pump. if you remove it you may never get it back together again. 160.00 mistake that may well be.

Yes you can inject straight methonal into the pump at the inlet i use a regular syringe like for filling up a control line plane. i just go slow with it. I have run these engines for over a thousand flights. the only time i ever flush the pump is at the end of the year. I run a sullivan crap trap filter from the tank to the pump. and of course a filter in my fuel can.

I do not run onboard glow and the engine is mounted inverted also. I normally use powermaster 15/16 mixed 50/50 with powermaster 15% mean and green. I have also used coolpower 25%. S&W 22.5% Wildcat 15%Helimix and Wildcat 15% all with straight synthetics. My favorite fuel for it is 15/16 which is a 15% nitro with 16% synthetic. just can't get it anymore. I do not take the carb apart to clean it when i flush the pump it goes out the carb.

Also at the end of the day i do not run my engine dry i just drain the fuel. and put the plane away.
The most important thing to remember about the 140RX is the rear bearing. usually the stock bearing will go bad in about four gallons of fuel or 40 flights that will most definately affect the midrange and idle qualities. I replace my stock rear bearing using the OS140CFI bearing as soon as i get the engine i do not use the stock bearing.
I use a OS header on one engine with a ES carbon pipe
A mac header on one engine with a carbon pipe
a OS header with the stock OS aluminum pipe on the other engine.