fuel pump relay

[wizard-58]

Ok another problem that is doing my nut since doing everything on my car and passing the MOT ..it decides it doesn't want to run any more ..Ive run some diagnostic tests on it and it doesn't really come up with anything ..apart from all 4 glow plugs being faulty ?? Thinking to get all 4 reading bad its got to be something like the control unit ..so brought a new one and replaced it .same result car turns over lovely but just wont fire ..im now exploring possibility of fuel pump problems ..I've check all fuses unfact I dropped the glove box right out so I could check the wiring as well ..my question is where are the bloody relays I've looked everywhere I've even had the box under the bonnet apart and checked the 5 fuses located in small block there but I can't for the life of me find the relays according to diagrams they're supposed to be behind glove box but I can only find fuses ?? ive seen pictures of them being on the drivers side but nope .I am really stumped ..

[Leslie]

Heater plugs will not stop these cars running ,, the low pressure pump fitted to early models is prone to failure, you need to see if its generating pressure through software

[wizard-58]

ok thanks for that ill try and get the software checked again I take it your talking about the one mounted in the tank ? the reason I say this is a few weeks back I had a non start problem again when a friend of mine slammed the tailgate .I was thinking dodgy connection on the pump ?? but I maybe just clutching at straws ..

[Leslie]

I dont know if its in the tank or under the floor on your car if its under the floor a few careful taps and it may run brielfly and let you start the car but its likely needs replacing.you could try listening see if its running but ghey only run brielfly if no start ..my 2001 330d did something similar when I closed the boot too and needed a new underfloor pump.

[wizard-58]

ok thanks for that mine is an intank pump which i removed with lots of cursing .when power was supplied it blew all the fuel in it out upto 3 feet in the air so assume pump is ok ..have now put it back in car turns over fires up but stops straight away .so slight improvement have just ordered a new filter even though this one hasnt even done 5000 miles . have dropped the glove box and fuse box and found 3 x relays an absolute nightmare all the 3 the same and no idea if any of them are to do with the fuel pump .still trying to get one of them out to check it

[Leslie]

You moving it may have jolted it into life again , if you have your hand on the relay and get someone to crank it , you should feel the relay energizing with a click to see which one it is , if they really are the same part number you could swap them over but they must be exactly the same . The glovebox will have to come out id think to access them , youtube should be some help there with a how too do it

[X5Sport]

Relay location RHD

IMG_3413.jpeg

[wizard-58]

yes ive found them and they are an absolute pig s--t to get to let a lone remove Im thinking if the car now fires but wont run could it be something totally different .I fitted a new fuel filter this morning just to be sure the old one was fine and full of clean fuel cranked car over and again fires but wont run ???

[wizard-58]

ok list of things done .took lift pump out of tank pumps really strong put back in tank and connected hose to out let still pumps really well I did check power and earth leads before .fitted new fuel filter old one was pretty good ..fitted new SCV valve on high pressure pump ..whilst stripped checked and cleaned glow plugs fully tested 0.3ohm all 4 and got red with 2secs on battery test ..replaced also fitted new glow plug control unit ...removed relays ( finally ) marked them and swapped position ( they are all the same unit ) have removed and checked all fuses in relation to fuel and glow plugs ..car turns over occasionally fires but will not run .?? in previous 2 weeks had done over a 1000 miles around cornwall and no problems really stumped now ..

[X5Sport]

Just a shot in the dark, but is the fuel rail pressure sensor OK? I know you’ve said nothing shows up on the diagnostics though.

Might be worth checking the wiring to the injectors as well in case something has a poor connection upstream towards the loom to them. Again it’s just a mental process of elimination. If it was running and then wasn’t, and you didn’t do anything it’s a hard one to track down. Dealers will use their diagnostic suite, but that comes at a (high) cost.

[wizard-58]

morning thanks for that ..a good mate of mine owns/runs a indi garage and he brought home his diagnostic tool .its a few grands worth so its caple of quite a lot ..we went through everything we could think off .when checking rail pressure even when only cranking it was raising to about 483 .I assume PSI both the FRP sensor and the fuel rail pressure control valve appear to opperating as speck ..my only concern is i fitted a new glow plug control unit but I heard you need to inform the ecu that its been fitted ( couldnt work out how to do that on mates tablet0 ??? also im getting a code for the map sensor ( dont think this would stop it starting) but going to remove and clean it today . ok update cleaned map and manifold hole got a new battery all refitted it attempted to fire but then nothing again just turning over . I cant believe how a car can be running fine then park it .and it wont start again after overnight its almost like a bits been taken away from it .??

[X5Sport]

There’s no need to recode the glow-plug controller, that’s plug & play. The weather isn’t cold enough yet to cause a no start without the plugs, it just takes a few more cranks.

The MAF (Mass Air Flow) sensor might be the problem as that tells the ECU how much air is going into the system. There have been several cases of the MAF causing trouble so have a search in the Forum. I’m not certain what impact it has, but it might cause the engine to stall. Only clean it with brake cleaner though.

[wizard-58]

thanks for that its just that im getting the code 4203 DDE glow plug control unit ..its new and i was told even though its plug n play i need to inform the ECU that its been changed ? i also changed the SCV valve but as pressure at rail seems ok i would assume that is all ok as well whether this would effect the starting i cant say .I will take up what you say a bout the MAF as ive had issues with it before but i c;eaned it with special maf cleaner and its been ok but you never know .

[X5Sport]

Is the replacement BERU? You can get issues between Bosch plugs and BERU controllers. If it’s Bosch or BERU it should be fine. Copy parts may not be 100% compatible or you may have bad wiring. Shouldn’t stop it starting though. No need to code as it’s just an on/off function with temperature.

[Lobster Pot]

I had this exact same problem turned over would occasionally run for about 2 seconds then cut out unfortunately it turned out to be the high pressure fuel pump