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Old 05-21-2011, 02:22 AM
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Diesel911 Diesel911 is offline
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I do not believe there is a Check Valve in the Fuel Retrun but you can see in the Lift Pump Rebuild threads there is 2 Valves inside of the Lift Pump. One of both of those Valve should keep the Fuel from going back to the Fuel Tank when the Car sits overnight.

There is a Fuel Pressure/Overflow Valve that is right before the Fuel exits the Fuel Injection Pump Housing. I believe on your model there is a small vent hole in the system that is supposed to allow for Air to bleed out of the Fuel Injection Pump Housing (this is one of the reasons there is no Hand Primer In the system). But, since there is a vent there I do not see how it would be responsible for holding the Fuel inside of the Fuel Injection Pump Housing to keep it from going back to the Fuel Tank.
Speaking of the same Valve I suppose it is possible (like in the 617s) for the Spring inside of the Pressure Relief/Over Flow Valve to have issues and not hold enough pressure during starting. And, sometime within that last week or 2 someone posted a pice of the guts of one of the Valve (don't remember the year but it was not s 617) and it had some plastic piece that was all buggered up.
I do not know if yours is the same or not.
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