[Dad's RV-10]

We’ve got four Lycomings in our hangar right now, and they all have slightly different priming requirements for instance.

Basically though, your steps 1-6 are “squirt some fuel into the cylinders”. My only thought is that if the throttle is only cracked when you squirt fuel, then you aren’t going to squirt much fuel. I always go full throttle, full mixture to prime, and then I know where I am when I “count seconds” for the fuel pump “on” step. I vary the number of seconds depending on the engine and the temperature. With the throttle only cracked, you’re telling the servo to deliver a very small amount of fuel.

The above quote is from another thread but proved to be very helpful for me.

Prior to buying my RV-7 this past year, it had been about 30 years since I last flew piston aircraft. It took me a while to realize but looking back, I probably had very few hours behind injected Lycoming engines. Back in the late 80's and early 90's, I had time in Cherokee 140-160-180's, Cessna 150-172's, Citabrias, Tomahawks, Seminoles, Dutchesses, etc. All of these have carb'd Lycomings. The Bonanzas, Barons, 182s, etc. I flew had injected Continentals. I flew other piston planes building my first 1500 hours but the point is, I had little time behind injected Lycomings. So it's no wonder I had no muscle memory for starting these engines.

When I acquired the RV-7, I did a lot of reading about P-Mags and researched starting procedures for injected Lycoming engines. I'd read numerous comments about P-Mag'd engines starting within a blade's rotation.

For whatever reason, the "priming" technique I'd settled on was to leave the throttle cracked, positioning the mixture full rich and running the fuel pump until nominal fuel flow (GPH) was indicated (and then cranking the starter with the throttle cracked and the mixture returned to full lean). While this worked, I definitely never saw the nearly instantaneous starts that P-Mag owners have reported.

After reading Paul's comment above, I decided to try running the fuel pump with the throttle fully open and the mixture full rich (and then cranking the starter with the throttle cracked and the mixture returned to full lean). Eureka! Now I agree with the P-mag owners who have written that their engines start nearly instantaneously! There's no question that running the fuel pump with the throttle fully open vs. slightly cracked has made a substantial difference in the starting performance of my engine (Aerosport IO-375).

I'm sure many of you are reading this and thinking "thanks for stating the obvious" but with decades since I last flew pistons, it certainly wasn't obvious to me.

Thanks to Paul for the good tip!

PS - "Cold" is a relative term. I'm in Florida, so I definitely haven't had to start the engine very much in actual cold weather conditions. I'm simply referring to starting the engine after it hasn't run for a day or more.