Fuel Pump Check Valve Test

Fuel Pump Check Valve Test

>I have been experiencing a minor problem for the past month:
>The car used to start up crisply on the first crank, but now takes 2 or
>3 cranks. However, if I press on the accelerator pedal slightly, it
>will consistantly start on the first crank.
>A previous post to the List said that failure to start on the first
>crank could indicate a defective fuel pump check valve.

Here is a simple test to check to see if the fuel pump check valve is most likely the problem.

Let your 928 sit overnight or at least 8 hours or so.
Instead of trying to start the car as you normally would, turn the key so you engage the starter for just a second and turn the key back off (do not let the car even try to start), do this 3 or 4 times in a row. Then try to start it like you normally would, if it starts OK at this point then it is most likely the fuel pump check valve.

Basically what you are doing with this procedure is "cycling" the fuel pump (the pump runs for a few seconds every time you engage the starter) to build up fuel pressure in the system.

Note: If you listen carefully every time you do the starter engagement as described above you should hear the fuel pump run for a second.

Due to the changes in the climate you may want to take a look at the connectors on you temp sensor II and also test it for proper operation.

David Roberts

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