Discussion:
Check Engine Light

Getting Code 73 and 74, We have replaced the fuel trim valve twice already replaced carb but still get these codes checked the O2 sensor according to the diagnostics and cant find anything that is giving the code any help would be greatly appreciated
  • Posted 2 Jul 2009 23:24
  • By grant89
  • joined 2 Jul'09 - 28 messages
  • Minnesota, United States
Showing items 1 - 2 of 2 results.
check duty cycle, need laptop
  • Posted 26 May 2015 09:44
  • By edward_m
  • joined 11 May'15 - 111 messages
  • Texas, United States
73=rich, 74=O2 sensor not switching because it stays high for extended time due to the over rich condition.
check vaporizer primary pressure, 2 - 3 psi.
check vacuum lines to and from trim valve for vacuum leaks, kinks, etc.
If mixer (carb) has been replaced as you state, the idle air has to be reset.
What color is the secondary diaphram in the vaporizer, if it is tan colored it has been known for heavy ends from fuel to bleed through diaphram then they get drawn into trim valve causing it to stick. Later diaphram is blue.
Also check the balance fitting at top of carb, should be an orfice not just a normal fitting.
  • Posted 7 Jul 2009 03:30
  • Modified 7 Jul 2009 03:31 by poster
  • By carl_v
  • joined 12 Oct'07 - 76 messages
  • Pennsylvania, United States

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