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Discussion Starter · #1 · (Edited)
Hi - I'm scratching my head over this one. I've got a 2003 325i with 121K miles.
Yesterday when driving down the highway, the car started losing power erratic cutting in and out.
Eventually died and could not be restarted - cranks but doesn't start. Codes were P0102 and transmission gear light, but seemed like a fuel starvation issue.
Today, I pulled the rear seat and there was no pump priming sound from the fuel pump.
So, I replaced the fuel pump (half hour job) and now it primes as normal for about 3 seconds when I turn the key on.
I expected that would fix it and the vehicle would just start normally...but again it just cranks and doesn't start.
Next, I checked the fuel rail pressure ---and it's ZERO...not just low...but zero. Clearly a fuel issue.
I've had to stop working for the night because I'm a street mechanic.

The fuel gauge reads a bit less than 1/4 tank. Instrument cluster OBC test 6.0 reads 028088 (left side tank 2.8L, right side tank 8.8L, which is about what I'd expect).
Other notes: I replaced the fuel filter at 111K miles (only 10K miles ago) and previously replaced the fuel pump was in 2014 (hard failure no prime situation)..
One comment I read is that the fuel tank need to be more than 1/4 full after replacing the fuel pump...perhaps it's not self-priming? And just to add some gas. Too late to try that tonight.

I'd really appreciate any thoughts on what the problem might be.
 

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'03 325iT Mystic Blau
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The pump motor primes just fine. That pretty much eliminates the relay as a problem unless I'm missing something.
Like fuel pressure? Lol

Seriously, I once had a Ford fuel pump relay partially fail so that it was only passing ~7VDC. It would run a brand new pump seemingly fine for a while until it just wouldn't anymore. I replaced so many pumps that were probably just fine on that car.

You haven't verified voltage to the pump, so basic troubleshooting says do that first.
 

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Discussion Starter · #6 · (Edited)
Are you getting pressure as it primes?
Are you getting pressure as it primes?
Nope. Zero pressure. My conjecture at this point is that fuel tank level is so low that the new pump isn't priming itself...so it's basically pumping air. The rest of the fuel system has also been sucked dry of any fuel by repeated attempts to restart. I plan on adding several gallons of gas tomorrow to bring the fuel tank level up to 1/2 and see what happens.
 

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E30M3 Race F10 535 R1150Rt M Coupe
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Not level!
Pump bad, pick up screen no good, voltage bad?
Should run because the pump picks up from a bowl inside the tank. Adding more will aggravate checking/changing again.
 

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Discussion Starter · #11 ·
Problem solved. And it shows the consequences of being a street mechanic working at night with just a flashlight. Am posting this so others can learn. When the sun was up, I tested the fuel pressure at the pump outlet - and it was fine. So, something was blocking the fuel line. I looked at the fuel line that connects to the pump and behold - noticed what looked like a tiny protruding piece of plastic. So, I pulled it out with some needlenose...and it was the protective cap for the pump output fitting from the new pump. It was transparent plastic and almost paper thin so I didn't notice it last night in the dark. And inadvertently inserted it into the fuel line where it completely blocked it. Photos attached. Removed the piece of plastic, reassembled and car started fine. Problem solved.
Tire Automotive tire Hood Wheel Tread
White Automotive tire Sleeve Textile Grey
 
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