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paulhunter-e28

518i Fuel pump stopped buzzing engine not starting.

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What a downer, good progress then today car started right up seconds later cuts out, refuses to start. Most out of chracter

 

Then i notice with turning on igniton, wheres the buzz gone? the buzzzzz with ignition has stopped

 

I checked the fuse all good, wiggled the fuel pump relay seems fine

 

drats. i dunno what to do? advice most appreicated. Ive never had an issue with the fuel pump supply ever.

 

 

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i got this useful info from sir Ant on a previous fuel pump issue, regarding the relay which im investigating and have removed - he has the following information which is correct to my relay  - if i can make a jumper wire to power the fuel pump at fuse box, I could determine if its the relay at fault or something else if the pump buzzes again, would be a direction at least.

 

 The relay has numbered pins;

30, red wire is battery 12v.

15, green is a harness connector.

Black/blue wire to ignition module and ECU

31, brown is an earth of course.

50, black yellow takes signals from starter motor, ECU.

87b, green/violet goes to the pump.

87, red white triggers the injectors.

To get a pump going you need a wire from the socket for 30 to 87b. To make it run, another wire to 87.

 

relay-pins.jpg


relay.jpg

Edited by paulhunter-e28

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Bmw no longer make this fuel pump relay blimey few on ebay germany however.

 

tried a jumper wire from pin 30 to 87b no buzzin :(

 

now im thinking relay maybe okay and my pump is dead?

 

 

Edited by paulhunter-e28

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This is my fuel pump, im thinking i need to attach direct power to it somehow to determine weather its operational or not, but i dunno how to go about testing a fuel pump. what a pain.

 

never been an issue ever untill today . Thankfully pumps not in the tank and subframe drop just to change the pump like a jag

 

i guess i could undo the electrical terminals on the right and see with multimeter if theres power going to pump with ignition on

 

fuel-pump.jpg

 

Edited by paulhunter-e28

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Hi Paul,

 

If your e28 has been stood for a few years and you still have the old fuel in the tank then this may be a cause as it could likely have blocked your fuel pump / fuel filter / in-tank suction pick up strainer.

 

If you are looking to remove the pump / filter assembly then both the Haynes manual and the Bentley Manual are a good source of information.

 

I have my fuel pump and filter off of the Diamantschwartz Eta at the moment conducting a re-fresh / overhaul.  I removed it with the wheels off, the car up on jack stands and the rear sub-frame in place.

 

Have a good weekend,

 

Best regards,

 

Mick

 

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thanks mick but after inspecting contacts to fuel pump, and me working on the rear parcel shelf speakers with rear seat lower out of place i think i may have pinched or broken a wire to the the fuel pump as thats what i was doing today and this only happened today. wiring geting old , much like my boot light. broken wire, connected to battery no problem. its very much a what was you doing before something went wrong issue. that fuel pump has never ever failed to buzz with ignition.

 

fuel pump fuse good. fuel pump relay clicking nicely. fuel pump contacts clean, removed them and tested on multi meter no power to pump at all 

 

only 2 wires to pump and its just through this hole at least i can trace it easily, but a gutting blow. to not hear that fine buzz and pressure to my injectors starts on the key.

 

ill have to cut the insulation to find the feeding wires. this is under the rear seat lower - drivers side to pump.

 

wiring.jpg

Edited by paulhunter-e28
spelling

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Hello Paul,

 

On my 535i with Motronic 1.1 the pump only activates when the engine is being cranked not when just the ignition is turned on. Therefore you need someone to crank the engine whilst you check for voltage on the pump terminals.

This is of course if the system protocol is the same.

 

Kind regards,

 

Ivor

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7 hours ago, paulhunter-e28 said:

thanks mick but after inspecting contacts to fuel pump, and me working on the rear parcel shelf speakers with rear seat lower out of place i think i may have pinched or broken a wire to the the fuel pump as thats what i was doing today and this only happened today. wiring geting old , much like my boot light. broken wire, connected to battery no problem. its very much a what was you doing before something went wrong issue. that fuel pump has never ever failed to buzz with ignition.

 

This was always the first thing I would do with the systems I worked on in the Navy.

 

When your system didn't work when you turned it on my first though was "what have I worked on since it last worked".  A few times this gave you a good place to start looking.

 

Good fault finding / diagnostic logic Paul :cool:

 

Looks like you are close to resolving your issue but keep a weather eye out for the advice Taffy gave you.  It might only be relevant to Motronic managed engines but it could potentially miss lead you to a wrong diagnosis and you look for a fault that does not exist.

 

I am not familiar with the M10 engine management set up on the 518i but there are members on this forum who are and hopefully they may chime in with some good advice.

 

In the mean time trace the pump supply cable back to the previous connector and see it you have power their.  If you do then you have a break between this connector and the pump.  If not keep chasing back until you find the power.

 

Have a good weekend and good luck fault finding.

 

Best regards,

 

Mick

 

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87b, on pump relay - green/violet goes to the pump. Heres something

 

this 87b green and violet wire you can see comes from the fuel pump relay - its something to have identified that - so does that mean thats the earth lead - or the power lead? the other lead to the pump is larger fit and brown wire, which usually means the power lead to my thinking. 

 

fuel-pump-contacts.jpg

relay-pins.jpg

 

Edited by paulhunter-e28

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Paul,

 

That is something I was going to suggest earlier.

 

Make sure that you observe polarity to the pump ( Body earth or negative ( - ) will be brown, the positive ( + ) should be  green with violet stripe.

 

That is directly the opposite of your previous theory. All browns are negative (chassis).

 

Kind regards,

 

Ivor

Edited by Taffy 1

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thanks im going with you so the green and violet wire is the positive wire sending power from pump relay - the brown is negative earth

 

thats good as the green and violet is easier to track

 

i could undo the green and violet wire from the pump unit - apply a 12v positive lead direct to the pump from a car battery and the pump may operate ? to confirm if the pump is alive or dead.

 

 

 

 

Edited by paulhunter-e28

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green-violet.jpg

 

This is green and violet wire that should send power to the pump from the relay then, seems in good condition, and i was able to unplug it at the connector block, apply my multi meter probe to the green violet circuit, where by i could reach the ignition switch inside the car to look for voltage under cranking, nothing. Its looking like a power cut situation.

Edited by paulhunter-e28

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if the fuse seems okay the jumper lead didnt do anything bypassing the relay

 

wiring looks good contacts clean im all out of ideas - ill just have to repeat checking things. I found this leccy diagram in haynes manual of my fuel system L Jetronic

 

It confirms sir ants info about jumper wire on pin 30 to 87b at the pump relay board

 

this clearly directs battery voltage to the fuel pump. 

 

leccy-diagram.jpg

 

 

 

Edited by paulhunter-e28

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jumper.jpg

 

So jumper lead in place, no luck then replaced fuel pump relay, turned on ignition.

 

And to my shock the Buzz had returned no idea why?

 

 

Its all back as it was before now, relay in no jumper wire, except half my interior is out again arghhh.

 

I made some observations while it was working in case it happens again,  and took some readings.

 

 

 

when i turned it off after this, i then turned on ignition to see if there was any reading at the pump. knowing its working again. and there was none. But there must be an initial something to get that buzz prime sound? time for a drink.

 

Many thanks for the useful advice, its car electrics that scares me on cars.

Edited by paulhunter-e28

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Have you taken out the fuses , cleaned them and the fuseboard fuse connectors, fuse no 1 appears to be the feed.

Edited by Taffy 1

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i did everything i cud think off including that. ive bought a new pack of 10 classic 16amp fuse's to replace fuel pump fuse - i dont want that again.

 

it does seem to have been a contact issue at the fuse box. resistance etc. 

 

it could have been so many different things. and the budget has gone for this car. 

 

when she fired up oh was so pleased. i cud bare too listen to my mums nagging - about scraping her. Nope

 

and my mum hates me big time as there was 60p off butter, and i didnt take her.? 

Edited by paulhunter-e28

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You jumped the wrong pins. The pin diagram on the relay shows the pin positions on the relay, so the pin (holes) on the connector are the mirror image. You jumped 87B to ground (31).

 

As an interesting but irrelevant aside, you were discussing electric current flow, but actually got it arse about face. The electrons flow from negative (-) to positive (+). That is to say, they flow from the battery  ground (-) terminal to the chassis, then from the chassis, through the Brown earth lead to the 31 terminal on the pump, through the pump and exit through the positive green/violet wire to the tachometric fuel pump relay and back to the battery positive (30). This is why you always disconnect the battery earth lead to disconnect the battery.

 

Anyway, pleased you got it working by exercising the joints. ie removing the relay and then reinserting it, scraping any corrosion off the pins/holes.

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im sure i plugged the right wires. the photo prob dont show it well

 

i cant tell you what team bmw have been through today

 

this was never an issue before!

 

who cares shes back to life whatever nothing happened untill the relay went back in. when im sober let me know what i did so wrong

 

prob sound proofing in the electrics and crud and all that

 

i think your right

Edited by paulhunter-e28

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Just to clarify my above comment. Pins numbered as per the diagram on the side of the relay.

 

51411634267_245747839b_h.jpg

 

Your connector with the receptacles numbered.

 

51413134959_32a8070c89_c.jpg

 

You had 87b connected to 31 (ground).

 

Its always best to check the wiring colours under the connector, just to be safe.

 

I realize that the pin diagram may be misleading on your relay, so I included a pic below of another fuel pump relay (E28 520i LE2-Jetronic which has a non-misleading diagram on it.

 

51411654567_03baf17157_h.jpg

 

Sorry to be a bore.

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