Mysteries Solved! How to Start a Fuel Injected Engine.
After seeing a couple guys struggling to start their fuel injected lycoming while working on an aircraft this afternoon; I walked out and started it on the first go. The pilot (who seemed to be on a group navex with his mates) looked a bit embarrassed and I reassured him that I had made the same errors when I first started out.
Considering that I had the same problems when I first flew an injected engine I thought I'd give some pointers on how to start them.
Lycoming normally aspirated engine
Cold Start
Mixture Rich, Throttle Fully open.
Prime the engine - turn on the boost pump, watch for the fuel flow to rise from Zero. Once the fuel flow rises wait one second and then switch the pump back off.
Mixture - idle cut off
Throttle - slightly cracked open.
Mags on, Crank the starter - As soon as the engine fires advance the mixture to rich.
Hot Start
Throttle - Leave it where it was when you shut down at 1000rpm.
Mixture - Idle cut off
Mags on, Crank the starter - As soon as the engine fires advance the mixture to rich.
***Note: on the odd occasion you may have to prime the engine with a splash of fuel if the engine doesn't fire after the second crank*** - as soon as the fuel flow rises, turn off the boost pump.
Sometimes you may get vapour lock in the injector lines after sitting on the ground for more than 15mins. To clear it, flood the engine with fuel. This will cool the injector lines back down and stop vaporising the fuel in the lines (then refer to the flooded start). You may notice fuel vaporisation just after start on the taxi as the engine will run rough. Turn on the boost pump and it will clear it.
Flooded Start
Ok, so you've flooded your engine from over priming it. This will be evident from the small puddle of fuel under manifold drain. We all do it from time to time. Those will attest that when we first jumped into fuel injected aircraft we all did it at least once - no big drama.
There are two ways about going about it. Obviously you have to clear the extra fuel from the intake manifold and the cylinders.
First way
Throttle - wide open
Mixture - Idle cut off
Mags on.
Crank the engine. The fuel/air mixture will start to lean out in the cylinders to a point where the engine will fire. As the engine lights pull the throttle back to near idle and advance the mixture all the way forward. Be careful not to over rev the engine on start - this takes some perfection. You will master it in the first couple starts when you have to use it. - This is the most successful way to start a flooded engine.
You could also open the throttle wide open, have the mixture at idle cut off with the mags off and crank the engine for say five seconds to draw the excess fuel out. Mags on, a splash of fuel and away you go.
It will take you a few flights to master the starts but at least you weren't totally thrown in the deep end.
Cheers,
Use all of the above advice at your OWN risk - just to cover my backside.