fuel pump relay

[wizard-58]

good morning well after a week of trials and troubles I'm no nearer ..yes high pressure fuel pump is a good shout ..why it should just go I've no idea .
so far I've tried 3 new glow plug control units a new SCV valve and I've just replaced the crankshaft sensor ( that's a lovely job ) taking a reading at R/w and B wires there's a constant 5v at yellow wire also a constant 5v which should be a switching voltage if engine is turned by hand with ignition on I didn't get this so changed it and no luck I've just done a fuel check running through from boot to the front and every stage there is a strong flow of fuel .I've checked the electrical connections to injectors they all give 0,2ohms . did a leak off test and hardly got a any fuel a couple of inch's up the pipe with about 12 cranks of the engine. we tried directly spraying a form of easy start and it doesn't even cough . I've also done at least a dozen diagnostic checks .code reads deletes and rechecks the only 2 codes that keep appearing is 4203 glow control unit and 4687 throttle Valve actuator ? I get NO fuel codes .. rail pressure sensor appears to be reading correctly .although when cranking expected pressure should be 398 bar .but actual pressure goes up to 398 for a millisecond then drops right off ( FRP control valve? ) voltage reading is correct /but no code for it ?
Im spending today researching all that I can think of online .
any and all suggestions will be checked .cheers
Paul

[Leslie]

Mt x5sd had throttle valve controller error , its a common issue , oil leaks in and damages the electronics , see plenty of new ones on ebay and not expensive and not your issue either , it seems mainly to close on ignition off and allow the engine to stop with less vibration so I've heard due to lack of air to compress , it has some role in regens I heard ,no idea what though but mine regens fine without it as its been broke a long time.

[wizard-58]

ok Ive sort of ruled out both the codes as being the problem if either were faulty it would cause issues but shouldnt stop it starting or trying to start at least ..so Im going to bite the bullet again this weekend and take the manifold off .I got a set of new glow plugs ( dont believe theyre faulty ) but while im in there this time ..im then going to do a full compression test and do fuel pressure test at the main rail feed and depending on the results ill have I hope an idea of which way to proceed .

[Leslie]

If its still alarming for heater plugs/controller maybe the controller isnt getting any power due to a fuse .wiring issue ? I think its unlikely new ones are faulty .

[wizard-58]

Okey dokey bit of an update cheers Leslie we have basically ruled out the control unit as being an electrical anomaly possibly because car isnt actually running .will do full exploration if it continues when we get her running ..compression test was very encouraging . cylinders as follows ;
1; 23 bar 2; 25 bar 3; 26 bar 4; 25bar or for us oldies 340 psi 360 psi 380 psi and 360 psi respectively all with in 15% of each other and very good ive been led to believe has car has done over 180'000m bmw say 16 bar at 325'000k is good so happy there ..Im now 99% sure it is the HPFP so have a reconditioned unit on its way hope to be able to fit this at the weekend delivery dependent .will up date as soon as completed .

[wizard-58]

next up date not encouraging .new/recon HPFP fitted at weekend and same results ??? even spraying easy start directly into throttle body only achieves a very minor cough no attempt to really start or run .now totally out of ideas ???

[Leslie]

Hi reading back you say throttle valve actuator , i dismissed this earlier as I have it too but if it won't run with easy start them the easy start can't be getting through , can you take of the boost pipe infront of the throttle valve and see if the butterfly is actually open with ignition on, it closes with ignition of or rather should but they often fail open and spray some easy start in there , hold it open if needed as if may have failed closed , as it really should be if it gets a source fuel, thats all I can think of . :thumbup:

[wizard-58]

yeah already done that mate by spraying easy start in to throttle valve I get a slight cough I didnt look inside though ill have a go this weekend when im at it again Ive also got new fuel pump pressure control valve coming ..not getting a code but hey ho in for a penny as they say .

[Leslie]

be worth checking the egr valve isn't stuck open too

[wizard-58]

ok have cured the throttle body code ( new throttle body ) old one was stuck closed now when spraying easy start car fires and runs 2 seconds ..but have now got code for crankshaft sensor even though already changed it .have done electrical test and getting constant 5v reading on switching wire which was reason for change originally .plan to strip out and recheck new crankshaft sensor and also do a fuel pressure test at rail from hpfp next Saturday .feel I'm getting close to the problem

[Leslie]

I hope u are getting somewhere , it can run anyay now , the throttle valve staying closed is unusual and the intermittent nature of it makes fault finding tricky till it failed totally, I might change mine soon so if it was getting fuel it would go , the crank sensor does tell the ecu its spinning over and if the rail pressure ix high enough it should go. Maybe refit the old one now if you have it , was the new crank sensor genuine ? If so its unlikely to be faulty , unlikely but not impossible I guess.