Petrol Diagnostics

Back to Forum

Post a Response

BMW 318 2000 - Non start, fuel pump relay switching on / off - Fixed #

Posted by Martin Simonsohn on March 9, 2011, 6:54 pm

Year of Manufacture *: 2000
Engine Size and Code *: 19 4 s1
( Optional ) Scanner Used: verus&launch
( Optional) Fault Codes: non

non start the customer has been on all the forums and changed the crank sensor then the cam sensor then subbed the coil pack and it still doesn't start fitted new plugs and set light to himself while spinning the engine over to see if he had fuel with the plugs out it shot a load of fuel out and the plugs that were in the end of all the leads sparked and lit it (i tried not to laugh)didnt cause any damage to the car (or him)
right i did a code read and it came back with co codes stored,code red the immobilizer and again no codes and live data showed keys recognized.
live engine data confirmed correct engine temp and air temp, when i brought up the engine speed/rpm data it was reading about 200rpm but dropping out to nothing. checked the dme relay ok then fuel pump relay pump relay switched positive/on then off and kept switching on and off while cranking.
suspected crank sensor checked with scope and it seemed to give an out put of about 5v p/p i thought might be a little low but haven't got a reference to another. asked where he got it from it came from a factors :-( here we go again tested the cam sensor ok
also checked the ignition and permanent supply and earth to ecu as well as the supply from the dme relay.
tried to scope the coil pack but the signal seemed to be erratic and difficult to capture.
it does try to fire but while cranking for about 30 seconds it will randomly fire now and again.
have recommended a new genuine crank sensor to be fitted and to confirm clean and properly mated surfaces.before going any further.
coil pack has a good feed under crank as does the ecu and fuel pump relay but as i said the pump keeps dropping out
did check the trigger to the relay from the ecu and it is definitely being pulsed looks almost like a square wave or duty cycle
can anyone suggest any thing i may have missed

Re: bmw 318is non start fuel pump relay switching on/off

Posted by Carl ford User icon on March 9, 2011, 8:47 pm, in reply to "bmw 318is non start fuel pump relay switching on/off"
Carl Ford

Hi martin
who fitted coil pack maybe customer has got leads on wrong also have you tried powering up the pump and then seeing if she starts and have the leads been changed not sure if this will help bit just a few things to check
Regards
Carl

Re: bmw 318is non start fuel pump relay switching on/off

Posted by martin simonsohn User icon on March 9, 2011, 9:21 pm, in reply to "Re: bmw 318is non start fuel pump relay switching on/off"
Martin Simonsohn

hi the leads are fitted correctly and yes i did try to feed the pump directly also by grounding the relay and it made no difference
thanks

Re: bmw 318is non start fuel pump relay switching on/off

Posted by Carl ford User icon on March 9, 2011, 10:13 pm, in reply to "Re: bmw 318is non start fuel pump relay switching on/off"
Carl Ford

Ok just re read your post and had a think and if he caused a fire checking for spark maybe the car could have a blocked exhaust (cat collapsed) maybe worth trying to start with lambda sensor out
regards
carl

Re: bmw 318is non start fuel pump relay switching on/off

Posted by Paul Mccooke User icon on March 9, 2011, 10:47 pm, in reply to "bmw 318is non start fuel pump relay switching on/off"

Hi Martin,
i had a major do with one of these end of last year, and learnt a lot from it, which is good because i didnt get paid for all the hours i put in, but my scope skills and diagnostic approach took another step forward from it.Cam sensor, mine would not run with a non genuine sensor, the signal was a1, just not in the correct place/time and mis-phased the ecm , they will run with cam sensor unplugged,as it will double fire the coil pack. The one i did came in very hard to start in cold weather, and would wet the plugs, but would start ok after a 2 hour warm in the workshop and start a1 for the rest of the day. To cut a long story there was no cam signal when cold,(cam sensor faulty) which meant the ecm stayed in its crank map, which meant its injection pulses stayed at 29 ms which meant wet plugs and no start, if we did manage to get it running cam sensor came good after 20 secs running. I'm wondering if this is the cause of your customers thermal incident. HTH Paul
BTW i would have openly laughed at him

Re: bmw 318is non start fuel pump relay switching on/off

Posted by Simon Forsey User icon on March 10, 2011, 7:41 am, in reply to "Re: bmw 318is non start fuel pump relay switching on/off"

Hi

I think it may be a good idear to take a step back and check the cranking volts and current. Its is suprising how many of these faults occure due to poor/faulty batteries.

Regards

Simon

Re: bmw 318is non start fuel pump relay switching on/off

Posted by martin simonsohn User icon on March 10, 2011, 6:31 pm, in reply to "Re: bmw 318is non start fuel pump relay switching on/off"

hi carl exhaust blocked doesn't effect the pump relay pulsing and you would still get an even spark
paul i did check the cam sensor signal at the ecu and that was good but im worried about the crank sensor as i could do with some time getting my library up together until my scope exp gets better
and simon the battery on the vehicle was almost flat so i was using MY heavy duty GOOD set of jump leads and there was little difference and the volts were giving a good reading just under 10v on crank as my secondary 12v supply is 220ah at 12v deep cycle

Re: bmw 318is non start fuel pump relay switching on/off

Posted by Carl ford User icon on March 10, 2011, 7:56 pm, in reply to "Re: bmw 318is non start fuel pump relay switching on/off"
Carl Ford

I will scope my other halts BMW 318 crank and cam tommorow when I get home and take a look a fuel pump relay as well if it would help
regards

Re: bmw 318is non start fuel pump relay switching on/off

Posted by martin simonsohn User icon on March 10, 2011, 9:46 pm, in reply to "Re: bmw 318is non start fuel pump relay switching on/off"
Martin Simonsohn

thanks carl thanks for the offer but the crank and cam are only testable under the intake/pelum chamber or at the ecu both will take you a good 1/2 hour to get to im going to wait till Monday then ring him and find out before he get the ecu back in then i can get the breakout box in there and take all the readings i need im hoping the original oe crank sensor will sort it.
spoke to a bm specialist today and he said that he will only fit genuine sensors.
mind while people keep using cheep crap parts it keeps me busy and the scrap bin full

Re: bmw 318is non start fuel pump relay switching on/off

Posted by paul mccooke User icon on March 10, 2011, 10:24 pm, in reply to "Re: bmw 318is non start fuel pump relay switching on/off"

http://www.mediafire.com/?hvxjp4rc40tdepe http://www.mediafire.com/?yth8uf6ih8awiny

Hi Martin, first one is non oe second one oe.
If you dont use pico just download pico automotive 6 software then you can view them.
Sorry everyone if this is not the correct way to post images its my very first attempt!
Any critisism/advice most welcome
Paul

Re: bmw 318is non start fuel pump relay switching on/off

Posted by Carl ford User icon on March 11, 2011, 7:12 am, in reply to "Re: bmw 318is non start fuel pump relay switching on/off"

V

Re: bmw 318is non start fuel pump relay switching on/off

Posted by martin simonsohn User icon on March 11, 2011, 11:02 am, in reply to "Re: bmw 318is non start fuel pump relay switching on/off"
Martin Simonsohn

hi paul i did manage to view the upload from you i think you readings were taken at idle i will try and get back there on monday and take some readings at both idle (if it starts) and at crank for my waveform library. trouble is i rarely get to test good traces as most of the time i am there to diagnose the fault and the garage repairs and it goes out the door.
however there is one garage who if i ask they will keep it for me so i can retest and take a recording of a road test for my files. a workshop would be nice sometimes trouble is mobile makes sense most of the time esp in the sticks.

Re: BMW 318 2000 - Non start, fuel pump relay switching on / off #

Posted by Alan Kane User icon on March 11, 2011, 12:54 pm, in reply to "BMW 318 2000 - Non start, fuel pump relay switching on / off #"
Alan Kane - Administrator

Hi Martin,

Crank sensor 5v peak while cranking sounds ok to me. If it scopes ok I think I would be happy with that. Did you scope the CMP as well?

The engine speed dropping out in live data is odd. Did you scope the signal while looking at live data to see if it dropped out. Remember that could be a scanner problem too.

<<< checked the dme relay ok then fuel pump relay pump relay switched positive/on then off and kept switching on and off while cranking. >>> Do you mean the neg trigger was pulsing?

The fuel pump relay coil pos is supplied from the DME relay so not sure how the DME relay could be ok while the FP relay switching? The ECU supply from the DME relay is the same one that supplies the FP relay coil pos. The FP relay coil should have a constant supply from the DME relay and the neg should be switched by the ECU.

Check the supply voltages and grounds while cranking. I would scope every pin at the ecu while cranking to isolate the pulse on the ground circuit. If your supplies and grounds are good and there is no fault with the inputs, ckp, cmp, ews etc then it sounds like an ecu fault.

Re: BMW 318 2000 - Non start, fuel pump relay switching on / off #

Posted by martin simonsohn User icon on March 11, 2011, 1:33 pm, in reply to "Re: BMW 318 2000 - Non start, fuel pump relay switching on / off #"
Martin Simonsohn

hi alan the supply to and from the dme relay is ok its the neg switch from the ecu to the pump relay that is switching on and off live data showed a peek intermittently of 400 rpm at that point it coffed but nominal rpm was either 200rpm or nothing.
ews?? immobilizer? i did use the launch to check the immobilizer module and it checked fine with keys recognized and no comms problem with ecu
i did check the cam sensor output at the ecu and it tested ok in hine sight i should have scoped them together but i have not had a chain jump on in of them as yet
the story is was running fine and died on approach to roundabout
ecu will allow start with out cam eventually but will not with out crank
when i looked through archive there is a 1.8 in there with cam sensor fault non genuine fitted was sorted by genuine one getting a little fed up with pattern parts they don't seem to work properly if at all

Re: BMW 318 2000 - Non start, fuel pump relay switching on / off #

Posted by paul mccooke User icon on March 11, 2011, 4:53 pm, in reply to "Re: BMW 318 2000 - Non start, fuel pump relay switching on / off #"
Paul McCooke

Hi Martin,
to comfirm, yes, both captures at idle.
Capture two, non oe, i managed to get by starting and running engine with cam sensor pulled out of head, then pushing the sensor in, which made it cut out straight away and not restart. Nearly makes you go blind trying to see the difference in the two cam waves, it's best to print them off

Dont know if oe sensor will cure the relay problems you have found,but your customer may have given it another problem by replacing cam sensor with non oe item, hth, good luck
Paul

Fixed #

Posted by martin simonsohn on March 18, 2011, 3:54 pm, in reply to "Re: BMW 318 2000 - Non start, fuel pump relay switching on / off #"
Message modified by board administrator March 19, 2011, 3:07 pm

Hi just an update phoned the customer today as i haddent heard from them and they have fitted the genuine sensor put it all back together and it has sprung into life

happy days.

I would like to thank all people with their input and scope traces it was a good exercise.

howerver it would have been nice if the customer had rung to say all was good they would have been quick enough to get on the phone had it not have started,but all thats well ends well.
Thanks again

[ Petrol Diagnostics ]

Copyright © uk autotalk