On Jul 16, 2:04 pm, (Paul Tomblin) wrote:
I know that hot starting IO-540s is a subject for considerable debate. I
was taught a method that I was told worked 100% of the time[1], and up
until yesterday it had. But yesterday, after flying for an hour and then
sitting in the hot sun for half an hour waiting for customs, I couldn't
restart the Lance and had to have it towed back to the tie down area.

So what would you do in that situation?

I would use the last-resort starting procedure for injected engines.
It was taught to me years ago by an ATP/A&P/CFI owner of multiple
aircraft, and it has NEVER failed to work in my experience, on any
horizontally opposed injected engine that I have ever dealt with,
large or small, four cylinders or six, high compression or low,
Lycoming or Continental. Now I pass it on to you.

Mixture full rich
Full throttle
Run fuel pump a few seconds (if you have a fuel pressure/flow gauge,
run fuel pump until it stops coming up)
Fuel pump off
Mixture idle cutoff
Crank
When it catches (and it will), simultaneously enrich the mixture and
pull back the throttle.

Here's why it works:
With throttle and mixture full forward, the fuel pump forces cold fuel
through all the lines, cools the lines, eliminates the vapor lock -
and floods the engine.
With fuel pump off and mixture at idle cutoff, no fuel gets to the
cylinders.
With the throttle full open, lots of air gets to the cylinders.
With a few revolutions, the flooding is eliminated - the air-fuel mix
going into the cylinders starts out way too rich (flooded) but quickly
leans out enough for combustion.
Now the engine is running - all you need to do is keep it from dying,
by enriching the mixture.

It's not terribly important to pull back the throttle quickly, either
- just stand on the brakes. So if you can't do both (enrich mixture
and close throttle) at once, push the mixture rich and then pull back
the throttle.

It's not wonderful for the engine, but it's not terrible either. It's
not like you would ever cold-start it that way. It just ran recently,
there is plenty of oil everywhere and the engine is hot. And once you
get good at it, you will be able to complete the start procedure
without the engine ever going over 2000 RPM.

If you have a procedure that consistently works, stick with it - but
when it won't work - and most every injected engine I've ever seen
eventually refuses to start - this is the method of last resort.
Never seen it fail.

Michael