Diagnosing fuel pressure problem in Audi Q7 - P2294 code

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Jack@European_Parts

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If the complete stroke of the HP pump is impaired........ it will cause a hydrostatic vapor lock effect.
Also considered a boot strap effect.

https://en.wikipedia.org/wiki/Air_lock

http://dictionary.reference.com/browse/vapor+lock

Result is poor power and inadequate fuel under load.
You can have PSI for air at a sensor or even gage........ and not volume of actual fuel.

To date I have never had to change an HPP unless the bottom of the pump was so damaged from excessive wear to nub.
Even than I would knurl the bore with a special reamer I sourced.
Then add the lost material to the pump shaft by hard welding/anneal process and change the lobe + lifter for my own curiosity.

The pumps internally are pretty well made and VW-Audi rebuilds them the same way.

Now still I would be concerned as to what is causing the issue for the electrical fault .....the resonance? or bad actual regulation N276/N290 or wire/ECU.

Fortunately it all must come apart anyway for inspection, and measuring would tell you all you need.
Since we have a performance problem I hedge the "follower".......

You get the heated effect when air is compressed with fuel in an incomplete stroke.
 
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