Komatsu FG50ATU-10:
Backfire through intake system

Hello, wondering if any of you Komatsu guy's can help. I have a FG50 with a Nissan TB45 propane engine that periodically backfires through the intake blowing the air cleaner cap off. This only occurs under high revs when lifting,never when travelling.
I have went through the basics (fuel spark wires cap rotor plugs timing valves etc) but can't seem to pin point it. it doesn't throw a code and only seems to do it once a shift (once is to many) regardless of operator. This unit is run very hard though.

Any thoughts would be appreciated.
  • Posted 11 Aug 2010 07:06
  • Modified 11 Aug 2010 07:07 by poster
  • Discussion started by FORKLIFTCHICK
  • Alberta, Canada
Showing items 1 - 6 of 6 results.
Common cause 4 this is lpg set too rich and check inline flow valve not open 2 far
  • Posted 25 Jan 2020 22:07
  • Reply by Firerescue
  • New Zealand
Bryan
Gary & Frank are good first choices. They both have been known to cause the backfire issue you are speaking about. After cleaning out the distributor, double check your timing as well. If all else fails, pull the head and send out for a rebuild. We have seen bad/leaky valves in hard run trucks do this too.
  • Posted 27 Nov 2010 22:33
  • Reply by Jeff
  • Georgia, United States
I have found if the unit is in very dusty conditions, due to the dist cap is vented,it picks up dust under the rotor button cover.(three screws holds it down).Remove and blow out the pickup.( gets its timing from crank sensor)Good Luck
  • Posted 14 Nov 2010 03:49
  • Reply by frank_a
  • Georgia, United States
Check the camshaft, had the same problem and found one of the camshaft lobes had worn down causing valve to stay closed.
  • Posted 27 Aug 2010 18:32
  • Reply by catlover
  • Victoria, Australia
Thanks Gary but weve tried that.
  • Posted 12 Aug 2010 00:34
  • Reply by FORKLIFTCHICK
  • Alberta, Canada
I had the somewhat of the same problem. try replacing the MAP sensor.
  • Posted 11 Aug 2010 07:17
  • Reply by GaryE
  • California, United States

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