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Evening folks.

My 3.0ltr V6 ASB engine'd A4 recently flashed up a fuel pressure low code and the engine died.
Several attempts to restart the engine have proved unscucsseful so I had it towed home.

Since then I have done some rudermentery diagnostics and found the metering valve on the side of the high pressure pump to be faulty. So I stripped the pump off, replaced the valve and refitted.

However it still won't start.
Assuming I'm having a air lock problem (despite back filling the pump with fresh diesel) I have hard wired the lift pump in the tank and placed a second pump inline just after the fuel filter and purged the system and am happy fuel is in the rails and where it should be, but again she refuses to start.
Add some easy-start into the mix and it'll run but cuts out as soon as you stop feeding it.
I have pulled the plug on the crank sensor and checked it over with a meter and am reasonably happy its ok.
To double check the hight pressure pump I pulled the top most valve off so I could see inside the body and can confirm its in good shape, full of fuel and oscillating when cranked.

If you asked me to bet I'd say the pressure isn't high enough as it does squirt fairly hard out of the rails its certainly not the huge pressures they say the rails are supposed to be at.

I am pretty much out of ideas. I have a new pressure sensor coming but since I have fitted the new metering valve and cleared the codes its not returned.

Does anyone have any suggestions for my next step?


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pump solenoid    ok ??

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The solenoid on the high pressure pump? - yeah its brand new, I checked it before fitting, after the inital non-start after pump refitment and again using a independent power source today.

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Hmm - does it still run if you feed it easy-start? If so it suggests the pump partially blocked or faulty or a partial blockage further up the line. Seems pressure can't get high enough - as you said originally? How brutal is it to get a new pump, or one from a scrappy?

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No as soon as you stop spraying it dies.
To be fair buddy thats the conclusion I've come to.

I'm currently weighing the options on a used pump vs a recon/new.
The new fuel pressure sensor arrived today so I fitted that but alas no improvements. - I'm basically skirting round the 'I'm gonna have to replace the HPFP' issue lol.
I'm sorely tempted to pull this one to bits so see whats actually failed but obviously if the replacment carries a surcharge I can't go too mad with it.

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