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BF40D chick engine light and fault code 34

F

fvee91

Member
Looking for some help with an intermittent check engine light on a 2013 Honda BF40D (approx. 500 hrs).

Background:

  • Engine has always run extremely well.
  • Starts easily, idles smoothly, trolls all day and pulls full RPM.
  • No loss of power, no limp mode, no stalling.
  • Strong tell-tale at all times.
  • No overheat light, only the check engine light and buzzer.
The issue first appeared shortly after a service where I:

  • Replaced thermostat.
  • Adjusted valve clearances (a few were slightly loose).
  • Replaced the high-pressure fuel filter.
  • Attempted to reduce idle speed by adjusting the throttle stop.
The engine has done around 20 hours since, including a weekend at Lake Eucumbene, and continues to run well despite the fault.

Symptoms:

  • Check engine light comes on intermittently.
  • Clears with a key cycle.
  • Originally seemed to occur mostly after sustained high RPM operation.
  • More recently it can occur after long periods of trolling/idle as well.
  • Engine continues to run normally when the alarm is active.
I eventually retrieved the fault code:

  • 3 long flashes followed by 4 short flashes.
  • No pause between them.
  • Repeats continuously.
I have not been able to get a definitive answer from Honda as to what DTC 34 corresponds to on a BF40D.

Recent developments:

  • I've noticed the engine may be taking slightly longer to start than it used to (hard to quantify, but perhaps an extra 3-5 seconds of cranking occasionally).
  • One warm restart after sitting for 10-15 minutes required a couple of attempts and coughed before starting.
  • Once running it was completely normal.
  • On the flush muffs at approximately 3000 RPM I observed the engine hunting up and down by about 250 RPM continuously. This was new behaviour.
  • Occasionally I think I can smell fuel, although I have found no visible leaks.
Checks already performed:

  • Thermostat removed and inspected.
  • Cooling system checked.
  • MAP sensor removed and inspected (looks like new).
  • MAP connector clean.
  • 5V reference and ground present at MAP connector.
  • Fuel filter housing O-rings have now been replaced.
  • All sensor connectors disconnected, inspected and reconnected.
  • No visible corrosion anywhere.
  • Engine oil level and condition normal.
At this point I'm trying to determine whether I'm dealing with:

  • MAP sensor / MAP circuit issue,
  • Fuel pressure or fuel delivery issue,
  • Crank position sensor issue,
  • Or something else entirely.
Has anyone seen a BF40D with similar symptoms, or can anyone confirm what 3 long + 4 short flashes actually means on this engine?
 
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