Hi everyone. I'm plagued by hot start problems and am wondering what techniques are working for you if you have a engine similar to mine.
My firewall forward is probably nearly as stock as a person can get. I have a YIO-540-D4A5 with AVStar AVX-5VA1 and two Slick mags, left one with a retard breaker (exactly what the factory new Lycoming purchase option from Van's came with). I also have a "SlickStart".
I don't have a fuel return line - the fuel is plumbed as per Van's plans flowing through the fuel filter, boost pump, engine pump, fuel flow transducer, fuel servo, spider on top the engine, and then the injectors. The only deviation from plans here was to place the fuel flow transducer after the engine pump on recommendation from the manufacturer, not before as Van's plans call for. This eliminated a problem I had earlier with erratic fuel flow readings.
Normal starts when the engine is cold work great. I open the throttle about 1/2", boost pump on, mixture rich for around 5 seconds to where fuel flow and pressure stabilizes, mixture ICO, boost pump off, crank the engine and go mixture rich when it starts, usually within a second or two.
If I shut down and start up again fairly quickly (within 10 minutes or so), a procedure that usually works for me is even simpler - all I do is open the throttle around 1/2", leave mixture at ICO, don't run the boost pump or anything, and then crank the engine and go rich when it starts.
But I have no luck at all if the engine has been sitting for longer (30 minutes to a couple of hours). Even if the engine doesn't feel that hot to the touch, I can't get the engine running with either technique for the life of me - it just cranks with no life at all. The only way I've been able to get the engine started is with a flooded start - full throttle, mixture ICO, boost pump on (left on), mixture rich for 2 seconds then back to ICO, crank the engine and then use 3 hands to get the throttle back and mixture forward when it starts. Usually my third hand doesn't work fast enough and the engine surges at high throttle when it starts, which is why I hate that approach. And its made me apprehensive about flying somewhere for just a short stop.
It's always done this; it's not something that just recently started happening.
And on the last annual, I cleaned and gapped all the spark plugs as perfectly as possible, as well as adjusted both magneto timings to be spot on (resulting in the same 90 RPM drop on either magneto during a runup).
Surely there has to be a technique that works better than this? I know the trick is to get colder, non vaporized fuel into the lines without flooding the engine, but I haven't sorted out a way of doing that trick.
I know that people with a fuel return line don't really have the same hot start challenges since they can purge their fuel lines with cool fuel properly. I don't know the intricacies of fuel return line plumbing though - would it be possible to retrofit my fuel system with a return line without having to change everything out?
Thanks for any advice you can provide! I'd love to start being able to fly places for an hour or two without being worried I'm going to be stuck there... starting the engine has become the most stressful part of my flights.
Dan
My firewall forward is probably nearly as stock as a person can get. I have a YIO-540-D4A5 with AVStar AVX-5VA1 and two Slick mags, left one with a retard breaker (exactly what the factory new Lycoming purchase option from Van's came with). I also have a "SlickStart".
I don't have a fuel return line - the fuel is plumbed as per Van's plans flowing through the fuel filter, boost pump, engine pump, fuel flow transducer, fuel servo, spider on top the engine, and then the injectors. The only deviation from plans here was to place the fuel flow transducer after the engine pump on recommendation from the manufacturer, not before as Van's plans call for. This eliminated a problem I had earlier with erratic fuel flow readings.
Normal starts when the engine is cold work great. I open the throttle about 1/2", boost pump on, mixture rich for around 5 seconds to where fuel flow and pressure stabilizes, mixture ICO, boost pump off, crank the engine and go mixture rich when it starts, usually within a second or two.
If I shut down and start up again fairly quickly (within 10 minutes or so), a procedure that usually works for me is even simpler - all I do is open the throttle around 1/2", leave mixture at ICO, don't run the boost pump or anything, and then crank the engine and go rich when it starts.
But I have no luck at all if the engine has been sitting for longer (30 minutes to a couple of hours). Even if the engine doesn't feel that hot to the touch, I can't get the engine running with either technique for the life of me - it just cranks with no life at all. The only way I've been able to get the engine started is with a flooded start - full throttle, mixture ICO, boost pump on (left on), mixture rich for 2 seconds then back to ICO, crank the engine and then use 3 hands to get the throttle back and mixture forward when it starts. Usually my third hand doesn't work fast enough and the engine surges at high throttle when it starts, which is why I hate that approach. And its made me apprehensive about flying somewhere for just a short stop.
It's always done this; it's not something that just recently started happening.
And on the last annual, I cleaned and gapped all the spark plugs as perfectly as possible, as well as adjusted both magneto timings to be spot on (resulting in the same 90 RPM drop on either magneto during a runup).
Surely there has to be a technique that works better than this? I know the trick is to get colder, non vaporized fuel into the lines without flooding the engine, but I haven't sorted out a way of doing that trick.
I know that people with a fuel return line don't really have the same hot start challenges since they can purge their fuel lines with cool fuel properly. I don't know the intricacies of fuel return line plumbing though - would it be possible to retrofit my fuel system with a return line without having to change everything out?
Thanks for any advice you can provide! I'd love to start being able to fly places for an hour or two without being worried I'm going to be stuck there... starting the engine has become the most stressful part of my flights.
Dan