Rossco Posted May 23, 2020 Share Posted May 23, 2020 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? Thanks Quote Link to comment Share on other sites More sharing options...
audia4b5kev Posted May 23, 2020 Share Posted May 23, 2020 pump solenoid ok ?? Quote Link to comment Share on other sites More sharing options...
Rossco Posted May 23, 2020 Author Share Posted May 23, 2020 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. Quote Link to comment Share on other sites More sharing options...
Prof Mat Posted May 24, 2020 Share Posted May 24, 2020 What fault codes is it throwing? Quote Link to comment Share on other sites More sharing options...
Rossco Posted May 25, 2020 Author Share Posted May 25, 2020 Originally it as a P0087 Low Fuel Pressure, but its not brought anything up since clearing it days ago. Quote Link to comment Share on other sites More sharing options...
Steve Q Posted May 26, 2020 Share Posted May 26, 2020 Since clearing the codes is it still doing it? Quote Link to comment Share on other sites More sharing options...
Rossco Posted May 26, 2020 Author Share Posted May 26, 2020 Still not starting, but now no error codes are listed. Quote Link to comment Share on other sites More sharing options...
Prof Mat Posted May 27, 2020 Share Posted May 27, 2020 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? Quote Link to comment Share on other sites More sharing options...
Rossco Posted May 28, 2020 Author Share Posted May 28, 2020 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. Quote Link to comment Share on other sites More sharing options...
Minty s4 Fresh Posted July 20, 2020 Share Posted July 20, 2020 You still having issues with this - I spent near enough 1700 the whole fuel system replaced pump high pressure low pressure sensor etc let me know think I know what your issue may be Quote Link to comment Share on other sites More sharing options...
GRIFF Posted March 2, 2021 Share Posted March 2, 2021 what was it?! Quote Link to comment Share on other sites More sharing options...
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