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Discussion Starter #1
Hi,I've 2004 BMW X3 E83 2.5i with 102000 miles and have a problem of cranking not starting. I would drive the car normal for let's say 3-4 days or so and try to start it sometimes it won't start it will be just cranking continuous. If I leave the car for a day or 2 it starts and drives normal until the problem reoccurs again.
I changed both the crank and camshaft sensors and it was okay for a while and the problem came back again. I've done further test myself using a multimeter,removed the rear seat turn the key on and the pump was just silent no intermittent hiss.I unplugged the fuel pump connector insert probes into some of the pins with reference I got from the net, I turn the key on and the voltage reading was very very low. Leave it a day or 2,I went back and did the test again,turn the key on checked and I could see the voltage is now reading much higher voltage between 11 volts for about 2-3 seconds and voltage drops. I suppose that's normal operation when relay kicks out causing intermittent hiss not to flood the engine. Plugging back the fuel pump connector turn the key on I could hear a fuel pump hiss the car could start if I were to give it a crank.

What could be wrong and causing this problem and where's location of fuel pump relay for this model? I'm just clueless and run out of ideas any help will be much aprreciated.

Regards

Lloyd
 

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the relay on my e46 is behind the glove box, not sure about yours. the horn relay is the same so you could just swap them round and see if it helps.
 

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Discussion Starter #3
Hi

I opened behind the glove box and I can see 4 relays, which includes 3 green relays and 1 orange. Counting from left to right the first relay is green the second is orange and the other 2 are also green, but I'm not really sure which one is the fuel pump relay.

Image attached image.jpg

Regards
 
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