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Discussion Starter #1
So recently I was left stranded with what appears to be a bad fuel pump relay (after Terrabass's useful video on testing it seems to point to the relay and not the pump):

https://www.youtube.com/watch?v=apOHpW_K_Lk&t=57s

Fortunately it was at a friend's house, so I plan to make the repair on site. Ordered the relay and will install when received. The problem with a fuel pump relay or fuel pump failure is that you are screwed. There is no "limp mode" to get you home when the engine is not getting fuel. I had a fuel pump failure at 126,000 miles. Now at 255,000 I am thinking to just go ahead and replace the pump (and fuel filter) as well.

Anyone on the board subscribe to fuel pump replacement even if it has not failed?
 

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So recently I was left stranded with what appears to be a bad fuel pump relay (after Terrabass's useful video on testing it seems to point to the relay and not the pump):

https://www.youtube.com/watch?v=apOHpW_K_Lk&t=57s

Fortunately it was at a friend's house, so I plan to make the repair on site. Ordered the relay and will install when received. The problem with a fuel pump relay or fuel pump failure is that you are screwed. There is no "limp mode" to get you home when the engine is not getting fuel. I had a fuel pump failure at 126,000 miles. Now at 255,000 I am thinking to just go ahead and replace the pump (and fuel filter) as well.

Anyone on the board subscribe to fuel pump replacement even if it has not failed?
I haven't but at that mileage, I would. How often have you replaced the fuel filter? ("Lifetime" per BMW hiha.)
 

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To answer your question directly first, there is no PM you can do for the pump. People will say don't run the tank down to low but I've never subscribed to that theory and I got more than 130k out of a replacement pump before it went.

For your situation, you should probably start thinking about replacing the pump. 100-130k miles is pretty typical lifespan. The relay may have gone bad because the pump is making it work harder all the time... gets hot and eventually died.

You could be weird like me and just keep a pump and a few tools in the trunk to change the pump where ever it dies... including on the side of I-90! If you've "been in there" before then you really don't need much... flatblade screwdriver, a hammer or in my case a small block of wood I keep to use with the scissor jack, and a razor blade from your temporary flat repair kit if you keep one. In order for this to work you need to just replace the pump itself. I've been running a Walbro. You have to change the connectors but once done, it's plug and play for another Walbro or the factory Pierburg.
 

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Discussion Starter #4 (Edited)
Yes, once I get it home, I am now thinking of replacing the pump anyway. I might keep the old one in the trunk per your suggestion. Still shopping for that since their seems to be significant cost differences and am curious if it is justified by performance or longevity.

A curiosity: When I go to realoem.com it shows the relay behind the glovebox as a normal 5 prong 86/87/30 relay. These are relatively cheap--generally a few dollars. But when I went to order, of course, the BMW one is special with 8 prongs and a $110 - $140 price tag. Example at FCP:

https://www.fcpeuro.com/products/bmw-fuel-pump-relay-z3-m5-m3-61357892976


But realoem.com is showing the 5 prong version here:

https://www.realoem.com/bmw/enUS/showparts?id=DE93-USA---E39-BMW-M5&diagId=61_4007

When I get back to my car with the part, am I going to be surprised when I drop the glovebox with the wrong relay?
 

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.... A curiosity: When I go to realoem.com it shows the relay behind the glovebox as a normal 5 prong 86/87/30 relay. These are relatively cheap--generally a few dollars. But when I went to order, of course, the BMW one is special with 8 prongs and a $110 - $140 price tag. Example at FCP:
https://www.fcpeuro.com/products/bmw-fuel-pump-relay-z3-m5-m3-61357892976

But realoem.com is showing the 5 prong version here:
https://www.realoem.com/bmw/enUS/showparts?id=DE93-USA---E39-BMW-M5&diagId=61_4007

When I get back to my car with the part, am I going to be surprised when I drop the glovebox with the wrong relay?

If you drop the glovebox, you will find the relay that was pointed to in your realoem link, but you will be disappointed if you buy a new one of this type of relay and install it: It is not the real EKP-relay (K96)! The EKP-relay (K96) is in the trunk, the big black one behind the right cover with 8 pins. The fcpeuro link shows the correct relay, only their price isn't right and that of several other providers ...

The EKP-relay is a PWM (pulse width modulation) controlled relay. I have to look up which of the smaller pins receives the PWM-signal. The flow of your fuel pump is controlled with it. Another small pin receives a signal from the DME (engine management unit) if the EWS (drive away protection) allows it. A missing signal there or a missing pin, if you would insert a standard 5-pin relay, will prevent your car from starting ...

On realoem the right (8-pins) EKP-relay (K96) can be found here:
www.realoem.com/bmw/enUS/showparts?id=DE93-USA---E39-BMW-M5&diagId=61_4492#61357892976

My remark above about the 'wrong' price, is based on the realoem price for a K96 relay, BMW no. 61357892976, of $40.25 and the experience that realoem-prices are always above actual prices. Things have changed now obviously, if I look at prices of other suppliers on the web ...
 

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Discussion Starter #6
All,

Thanks for the help!

OK, so from the research it seems that for 2001 and later (mine is a 2002) the relay is behind the glovebox--not in the trunk. Not sure that was an improvement.

Once the glovebox is dropped, will the 8 pin relay plug in there?

Thanks
 

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All,

Thanks for the help!

OK, so from the research it seems that for 2001 and later (mine is a 2002) the relay is behind the glovebox--not in the trunk. Not sure that was an improvement.

Once the glovebox is dropped, will the 8 pin relay plug in there?

Thanks
Nah, pretty sure the fuel pump relay you're looking for is in the trunk. I remember there being confusion regarding WDS and its location.
 

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... OK, so from the research it seems that for 2001 and later (mine is a 2002) the relay is behind the glovebox--not in the trunk. Not sure that was an improvement. Once the glovebox is dropped, will the 8 pin relay plug in there?
Thanks
If you click the part number 61357892976 behind the 8-pin K96 relay, you should see the reference 10/1997 - 06/2003. That gives reason to think that the same 8-pin K96 relay is used for all years of build. Maybe M5's before 2001 are different, but not later versions like your 2002 (and mine 2003).
Before uninstalling the glove box, I would first have a peek behind the right cover in the trunk. If there's no big black relay in there, then have a look behind the glove box ...
 

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Discussion Starter #10
Confusing literature.

Manuals online states it is in the trunk:

https://workshop-manuals.com/bmw/5_series_e39/m5_s62_sal/2_repair_instructions/13__fuel_system_(s62)/63__throttle_potentiometer_fuel_pump_relay/2_ra__replacing_fuel_pump_relay/

Realoem shows it behind the glovebox. This is after putting in the last 7 digits of my VIN--so it would seem this is most accurate. Again showing a standard relay:

https://www.realoem.com/bmw/enUS/showparts?id=DE93-USA-06-2002-E39-BMW-M5&diagId=61_4007

What?!
 

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The bimmerfest link shows an E39 indeed, but not an E39 M5: Our M5 battery is sitting in the middle of the trunk. If you scroll a few plots downwards on the bimmerfest link, you can see the battery sitting on the right side of the trunk, under the relay carrier. The relay setting between various E39 models differs considerably.

The realoem plot-location of your wrong (5-pins) relay, shows the right location for the black, 8-pins*, EKP-modele = K96 relay: The relay carrier, behind the right side cover, in the trunk.

Before dumping your present K96 relay, you could have a look inside (open it up with 4 cocktail-sticks between bottom plate and the casing walls). Re-solder the connections of especially the small pins 1 and 7 to the PCB. You'll need a regulated soldering iron for this, because the solder connections require a bit increased temperature setting before they melt.

*) Only the relay female-connector X10156 has 9 pins. Connector 3 is not occupied. Connectors 4, 5 and 9 carry no wire. You would almost start thinking 5-pins is enough ...
 

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Seems we have to do this again. I get this is a hard topic because it is confusing, the company puts out poor and incorrect information. I just thought that a topic that has caused so much anger and frustration in the past, might have lessons that stuck.

You have to identify you relay physically. If it is the standard relay then that is in the glove box(after a certain year), but if it is electronic (big black) it will be in the trunk.
The difference between the two devices is for OBDII compliance. There has been discussions and some evidence that standard relays might have gone in some US cars, but to the best of my knowledge no one here has ever found one.
Euro cars and others not using OBDII are different. There have been more than a few later model UK cars that did have a standard relay, then to make matters worse it was in the freaking trunk!

YOU MUST FIND YOURS IN CAR! Although on a NA car it seems super likely it will be electronic and in the trunk, it is said some were made the other way. These parts do not interchange because the DME has different programing for both.
 

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Discussion Starter #13
Seems we have to do this again. I get this is a hard topic because it is confusing, the company puts out poor and incorrect information. I just thought that a topic that has caused so much anger and frustration in the past, might have lessons that stuck.

You have to identify you relay physically. If it is the standard relay then that is in the glove box(after a certain year), but if it is electronic (big black) it will be in the trunk.
The difference between the two devices is for OBDII compliance. There has been discussions and some evidence that standard relays might have gone in some US cars, but to the best of my knowledge no one here has ever found one.
Euro cars and others not using OBDII are different. There have been more than a few later model UK cars that did have a standard relay, then to make matters worse it was in the freaking trunk!

YOU MUST FIND YOURS IN CAR! Although on a NA car it seems super likely it will be electronic and in the trunk, it is said some were made the other way. These parts do not interchange because the DME has different programing for both.
Sailor,
I seen where you had some passion around this topic in previous posts to where you were engaging your engineer friends to come up with something better.

My trunk does not have the big black relay in the trunk that I recall (US 2002 E39 M5), but the part I ordered is the big black relay based on my VIN and the part supplier. That is why I was assuming (perhaps wrong) it would be behind the glovebox.

I will certainly find out soon when it arrives and I ride my bicycle to my car with relay in hand and hopefully start it with said bicycle on roof when coming home to then also change out the pump and filter. Otherwise it will be an angry round bike trip to get the right relay!
 

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Discussion Starter #15
Take a paper clip with you! I take it you have not found this thread?
https://www.m5board.com/vbulletin/e39-m5-e52-z8-discussion/206282-suddenly-stranded-testing-your-fuel-tank-levels-fuel-pump-relay-fuel-pump-10-minutes-piece-copper-wire.html
That is where you should have been directed first. Does not mater which relay you have jump it with a paper clip and the fuel pump should run unless the issue is the pump or wiring to it.
The big relay just arrived now. After all this, I still don't know where it goes! That seems like it should be simple. I will bring jumper wire in any case--good idea!
 

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If you don't know where it goes you are the only one to blame for that. Even if you just had clicked the link and not really even read it, you should not have missed the second picture in the thread, but there are more to help you understand.
 

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Discussion Starter #17
Sailor,
Not so much. As stated, there is confusing literature that I have read and I do not have the luxury of the car with me to check at this time. It certainly looks like it will be in the trunk—and if not, out comes the glovebox.

Thanks anyway.
 
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