Starting & Hot Starts

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Starting & Hot Starts

Post by AndyB on Sun Jun 25, 2017 12:21 am

Following a brief discussion of starting between Mig & Bill today, Bill gave his view on the starting process as follows:

  • Fuel - Main
  • Throttle - Closed
  • Mixture - Lean
  • Master - On
  • Boost Pump - Operate (Wait for Fuel Pressure to reach 20 or max attainable)
  • Boost Pump - Off
  • Mixture - Rich
  • Mags - On Both
  • Boost Pump - On
  • Starter - Operate for 10 secs


If the engine fails to catch, wait 5 secs before re-engaging starter for 10 secs.

On starting Hot (following an ICO shut down at the pumps).


  • Fuel - Main
  • Throttle - Set 1/8" Open
  • Mixture - Rich
  • Master - On
  • Mags - On Both
  • Starter - Operate for 10 secs


Bill's theory is that it is easy to flood the engine, so better to start the process 'lean' and increase the fuel entering the engine for a successful start.

Mig & I had a chat about what might be happening behind Bill's recommendation (Forgive me for being a numpty on this...) Presumably:
using the Boost Pump with the Mixture at idle pressurises the fuel to the Fuel/Air Control Unit only.
Selecting Mixture Rich with the Boost Pump off means that as soon as the Boost Pump is re-selected before activation of the Starter will pressurise the fuel line to the Fuel Manifold Valve, and onwards to the cylinders, effectively priming them immediately before the activation of the starter motor.


Hot starts are notorious on fuel injection engines apparently because the warm engine's residual heat can build up under the cowling, vaporizing fuel in the injector lines and preventing it from reaching the cylinders in sufficient quantity to start.

Elsewhere online I have read the following regarding the IO-360:


  • Fuel - Main
  • Throttle - 1/4 Travel Open
  • Mixture - Lean
  • Master - On
  • Boost Pump - Operate (Wait for Fuel Pressure to reach 20 or max attainable)
    Priming:
  • Throttle - Wide Open
  • Mixture - Full Rich until slight fuel flow is noted (3-5secs), then to ICO
  • Mags - On Both
  • Boost Pump - On
  • Starter - Operate for 10 secs
    When engine catches:
  • Move mixture control slowly and smoothly to “Full Rich” and retard the throttle to desired idle speed.


Hot Start : Omit Priming Section.


Another Hot Start topic suggested


  • Mixture - FULL RICH
  • Throttle - FULL FORWARD for 10-12 seconds then set to 1,000 RPM/Idle (you should know where 1,000 RPM is on your throttle... but if you set 1000RPM on shut down with ICO & leave the Throttle in position, you will have a reminder)
  • Mixture - Full lean
  • Starter - Operate
  • Mixture - Smoothly advance to Rich as engine catches


The theory being that the 10-12 secs with the Throttle open gives a period for any vapour lock to equalise. Boost pump may be required on a subsequent attempt.


Anyone got any thoughts on our 'best practise" or any other comments that they might wish to put forwards?


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