2008 bmw x3 3.0 engine start then die right away

[terryjianlin]

So about a week ago my x3 start up then die right away, I checked the fuel pressure and it only came up about 20psi, I thought it was the fuel pumb failure . I went ahead change the fuel pump today. but it turns out still the same, engine start up then die. no change at all.
I also checked the electrical , multimeter read 12v when I crank it, seems to me no thing wrong with electrical connection to the pump.
my question to the experts on this forum is this: where else I should be look into? Does it have any thing to do with the fuel pressure regulator?

[dano1200r]

Did you change the fuel filter? And inspect the line?

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[terryjianlin]

Did you change the fuel filter? And inspect the line?

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I did not changed the filter , I do inspect the line and their connections, they are all in good shape .

[dano1200r]

A 10 year old fuel filter could be your problem, and needs to be changed anyway.

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[z3forlife]

When did you replace your air filter last. I had a similar issue until I replaced it

[terryjianlin]

Well, thank you every one!
So I replaced the fuel filter today, no thing, still unable to start the engine. I even apply direct power from battery to fuel pump, then crank the engine, which still no working. anyway this method tells me there is nothing wrong with fuel pump relay
please correct me if I wrong, As a new home machanic, for what I understanding so far, A no starting issue could be any of these problem:

A: Fuel delivery system mulfuntion ,they are FUEL PUMP ITSELF(good), FUEL PUMP RELAY (CORRECT VOLTAGE DETECTED WHEN CRANKING), FUEL FILTER(new), FUEL INJECTORS(waiting to be test)

B: Ignition system mulfuntion, they are SPARK PLUGS (ALL BRAND NEW), IGNITION COILS (untested)

Here is a list of things what I going to try tomorrow
1: put back the old spark plugs
2: bench test all the ignition coils and the ignition relay

Day 2

So I checked the fuel injector today, they seems working just fine. also tested the spark plug and coil , they looks fine as well [update: Checked the spark today again, it only appear when I got lucky]. Do get a Error code P0370 [timing reference high resolution signal A]updated: the P0370 did not came bake after I clear it.
anyway, engine did start one time. put my foot on the gas paddles to the floor and crank it. engine only run while I keep my foot on the gas , it die right after i take off my foot. Any suggetions?

Did not get any of the spark today, coil and spark plug are good.. test it with other X3.

[Sknoble]

You may have a crank/cam position sensor that is failing. A Cherokee I had did exactly that when the crank sensor failed.

[terryjianlin]

You may have a crank/cam position sensor that is failing. A Cherokee I had did exactly that when the crank sensor failed.

Well, my crank seror is brand new, I did get RPM as I crank the engine. as well as the camshaft sensor, it's good one, I pull it from my other X3.

my question is: Is ther A relay for ignition coil ? or what else I should be checking as I did not got a good steady sparks today ? I am running out ideas?

[dano1200r]

It ran with your gas pedal pressed? You may think your fuel pump is working but you need to test its pressure.
Also, how did you test the injectiors for pressure and pattern if you can't get the gas to it? Am I missing anything?

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[Sknoble]

Here is all the possibly info I have.
a friend had a early 90’s ford escort that would only run when you had your foot on the gas. It was the fuel pump. It got enough fuel to barley run. It was quite a few years ago, so I don’t have any other details. Plus that was and OBD1 system.
Maybe a fuel pressure regulator?
Many years ago I was told OBD2 is set up to clear an engine flood when you held the gas to the floor.
Maybe try a small shot of starting fluid in the intake after the filter. If it’s a fuel problem, the motor will breathe to life for a second as it runs on the starting fluid.
Hope somehow this info helps. I’ve got nothing else.

[Billwillems]

Have you checked your mass airflow sensor? Mine did something similar, and that’s what it was


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[Rustynuts]

Only other possible I can think of is throttle position sensing is messed up. Did you do any code clearing recently?

Simple fix on my 2006 is to switch key on (not start) and then switch off. Then immediately hold the gas pedal fully to the floor for 1-minute. Lift off and then start normally.

This happened to me when I cleared a lot of codes with myCarly. My car started then immediately died a few times, then if I kept starting it would run if I goosed the gas pedal, but ran rough/died at idle. tried the above and it worked like magic.

[WELSCH325i]

I had this problem with mine and could not figure it out. It turned out that I had a bad vacuum leak. When I put the intake back in, I must of knocked one the hoses loose or off. Cost me 300 for the garage to tell me I done f'ed up. Embarrassing.