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-   -   Confirm Fuel pump failure on crank no start (https://xoutpost.com/bmw-sav-forums/x5-e53-forum/110541-confirm-fuel-pump-failure-crank-no-start.html)

lo_jack 07-13-2019 08:21 PM

Confirm Fuel pump failure on crank no start
Hello everybody. I had my 3.0 down for maint for a LONG time. Battery somehow died, despite being on a trickle charger.

When I finally got everything back together (headers, VANOS), I tried to fire it up with a new battery and got crank no start. I have no codes on ODBII.

There is absolutely no fuel in the rail (checked at schraeder). After swapping fuse 47, I jumpered the fuel pump relay with a fuse and a switch per Bentley, and got nothing. No fuel pump sound, no fuel in the rail, no start.

Is there anything from the DME that would keep the fuel pump from energizing, or should jumpering bypass the DME altogether? Could something I could have done or not done when I had the coil packs out and half of the engine sensors disconnected to change the VANOS seals keep the fuel pump from energizing?

It seems like its dead fuel pump at this point, but I wanted to cover all the bases.


andrewwynn 07-13-2019 09:33 PM

You can use a drill battery or a charger to apply 12v directly to the pump or of course measure voltage at the pump. The thick wires are power the thin are the sensor.

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lo_jack 07-13-2019 10:19 PM

That's the plan. Jumper up the pump relay again and then see if I have voltage at the pump connector. If there's voltage and no pumping, she's dead, no?

The only thing I don't understand is if the dme can command pump off in some other electrical failure condition. if it can, then the pump could still be good but the dme says no voltage before the pump relay. In that case, jumper in the pump relay still wouldn't get the pump to go, right?

I've read some other threads that suggest the dme shuts the pump circuit down if it detects some other electrical faults with the engine.

andrewwynn 07-13-2019 11:59 PM

What you didn't say was if you already have voltage at the pump.

What you said was you "have nothing" but you meant was there was no audible sign of life. No need to jumper anything just measure if you have voltage at the pump

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oldskewel 07-14-2019 12:30 AM

If it were me, I'd keep it simple and apply 12V at the fuel pump (as AndrewWynn said initially).

Pull off the connector and figure out how to get 12V on the pins you need. That test cuts out any doubts regarding the DME, the relay, and even the wiring (which could be a problem you have not considered yet).

cn90 07-14-2019 02:50 AM

- You posted a message to get help but did not state mileage.

- If you have > 150K, I'd replace the fuel pump.

Search for Pierburg brand.

PS: Also search forum for the siphon O-ring issue, may be you have no fuel in the fuel pump side.

lo_jack 07-14-2019 03:30 AM

Checked for voltage at the pump connector, both jumpered and with the relay back in. I don't have any voltage whatsoever, but what I do have is some kind of hum and fast clicking coming from under the intake manifold that happens when the key goes to run and doesn't stop until I turn the key back to on. I can feel the intake manifold vibrate. No idea what that is all about, maybe DISA.

So, there's that. I have to figure out why there is no voltage at the pump connector. Pumps aren't that expensive and it looks easy to do. But no pump works without electricity, and I hate troubleshooting electricity because I am bad at it.


CN90, mileage 187k, but this is the second fuel pump. I think this has less than 60k on it, not many hours considering I used to daily it 40+ miles a day on the highway.

I think the noise is my ICV.

cn90 07-14-2019 05:16 AM

What is the brand name of the 2nd fuel pump?

andrewwynn 07-14-2019 06:45 AM

Won't get fuel pump if there is an EWS read problem. What scanner do you have and can you make sure your anti theft hardware is taking too the computer?

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lo_jack 07-14-2019 12:59 PM

Scanning with a Bluetooth elm and torque pro. Not sufficient for advanced diagnostic or ews. I have the old 20 pin underhood, but no pin 15. I need to get a ftdi cup cable and do your new 20min wire wrap, it looks like.

What cable are you using that will work with 16pin and your 20min bridged connection?

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