Fuel pump check valve

DasWolfen at aol.com DasWolfen at aol.com
Fri Sep 13 18:20:47 EDT 2002

 A failing fuel pump checkvalve can cause hard warm starting for a very
simple reason........HEAT. The fuel must be under a certain amount of
pressure to prevent it from boiling in the rail, ie: vapor lock. Not as much
a problem for injected engines as it was for carbs because the pump is able
to shove enough fuel at pressure to raise the pressure and cool the rail given
enough time. During cold starting the checkvalve isnt nearly as important in
an EFI engine. There isnt any vapor pressure in the rail to overcome and the
rail doesnt need cooling thereby masking the defective checkvalve.

 Phil, your idea will cause the ECU to switch into cold start/run strategy.
The problem is the only real effect is to increase the duty cycle of the
injectors during the start attempt, not cool the rail or eliminate the vapor


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