95 530i Engine will crank, but not start

[eelley]

I stepped into my car this morning and it would not start. The check engine light had been on for awhile but I have been putting off diagnosing it. I performed the stomp test, and code 1231 was returned. (Oxygen 2 sensor lean/rich control stop) I believe it is not related.



I then consulted Bentley to orient myself with the standard electrical tests.

I started by checking the fuel pump. The pump is receiving about 10 volts at the connector in the truck.

However I do not hear it running. How loud is it supposed to be? My ear is about 6 inches away from the pump when someone cranks the car.

Eric

[632 Regal]

dont think the pump runs constantly once at pressure, pull the line at the drivers side fuel rail and turn the key and see if your getting fuel, would be nice to have help with that test of fuel can go everywhere. I can NOT hear my pump at all EVER.

After this reboot the computer and see if it stars if you have pressure, if not we can troubleshoot farther.

[eelley]

dont think the pump runs constantly once at pressure, pull the line at the drivers side fuel rail and turn the key and see if your getting fuel, would be nice to have help with that test of fuel can go everywhere. I can NOT hear my pump at all EVER.

After this reboot the computer and see if it stars if you have pressure, if not we can troubleshoot farther.

Will do. I will check it first thing tomorrow. Thanks for the help.

[eelley]

Will do. I will check it first thing tomorrow. Thanks for the help.

Sorry for the long delay in responding Regal. It took me a while to find a spot to work on my car. I just moved to a new area, live in apartment and can not work on the car in the parking lot of the complex (written in my lease).

Okay..

Later that evening I removed the ECM. Someone posted that if the car fails to start, disconnect the ECU and reconnect after thirty minutes. The next morning I reinstalled it, the car started and has been running ever since.

ECM brain cramp?

??? Ummmmm?!!!

What do ya think?

[632 Regal]

weird stuff....did you do the reboot?

[eelley]

weird stuff....did you do the reboot?

If rebooting is unplugging the computer and replugging it the next morning, yes.

I agree, a bit strange.

[632 Regal]

I do the shogun reboot

[eelley]

I do the shogun reboot

Whats that?

[eelley]

Whats that?

Found the thread! Thanks

[Tiger]

Probably crank position sensor.

[R1daveg]

Replace the EGO's. It may not be the ultimate cause for not starting, but its not helping either. Engine will run much smoother and get much better economy too.

[eelley]

Probably crank position sensor.
I resistance tested the crank position sensor and the resistance read within specification of the Bentley Repair Manual. Could it be faulty and still be within electrical spec?

Eric

[eelley]

Replace the EGO's. It may not be the ultimate cause for not starting, but its not helping either. Engine will run much smoother and get much better economy too.

I agree. I ordered the parts yesterday.

[632 Regal]

why???
Replace the EGO's. It may not be the ultimate cause for not starting, but its not helping either. Engine will run much smoother and get much better economy too. the o2 sensors dont work when starting the car so this advice is absolutely incorrect!

[eelley]

Found the thread! Thanks
Well, rebooting the computer did not solve it. Darn. Just in case...I will perform the reboot again. Hoping that this would point to the DME itself.

Here are the things I have already checked:

Voltage at fuel pump during starting...OK (Assuming fuel and DME relays are fine)
All resistance checks on the coils measure within spec...OK
Resistance check on the crank position sensor within specs, (but on the low side) ..OK?
Tried to disconnect the fuel line at the rail, did not manage to remove it. The darn hose was on the fitting so tight and there is not that much slack on it. I did not want to risk of destroying it. I was going to disconnect at the fuel filters but decided to reinstall the DME. Thats when I tried to restart the car and it worked. So I figured problem solved......nope.

Now that the car is back at my apartment, I need to get it towed to a gargage to check to see if fuel is being pumped up to the fuel rail...again.

GGrrrrrrrr!

Eric

[eelley]

why??? the o2 sensors dont work when starting the car so this advice is absolutely incorrect!

The idle is rough when it does start. And another person at the parts counter of my local BMW dealer said that with a rough idle, and a check engine sensor throwing a code, the second O2 sensor is bad.

Separate problem, I figured.

[632 Regal]

let us know

[eelley]

let us know
Okay... Rebooted the computer one more time. Car does not start. However I have retested and now I see that I am not getting any power to the fuel pump relay. (swear I was before)

The DME/ECM relay is fine and engauges (which sends battery voltage to one side of the fuel pump relay coil when the ingition key is turned. The other side of the coil is connected to the DME module (pin1) which supplies the negative to turn the relay on.

This is not happening.

Has anyone seen this before?

[632 Regal]

bump for Javiar

[Javier]

it may not be energized if the engine is not running, no matter you are trying to start it. Best way to test fuel system is to bypass the pump relay, you will have a permanent pumping condition as long as the pump is OK. You can even hear the hissing of the fuel going trough the fuel pressure regulator. I would put the jumper there and try starting with the jumper in. If the car starts OK with the jumper, but not with the relay, then either your relay is wrong or your DME driving transistor responsible of energizing the relay is damaged.

To jump the relay you have to wire a jumper from the relay socket hole corresponding to pin 30 to the hole corresponding to pin 87. Careful not to miss it, as you can damage DME if connect 30 to 85. You can also wire jump some power to fuse F23 from a known good 12 Volts (Vbatt) source.

Guess you have already checked your CPS. No CPS means no spark and no fuel pump.

Javier

[eelley]

it may not be energized if the engine is not running, no matter you are trying to start it. Best way to test fuel system is to bypass the pump relay, you will have a permanent pumping condition as long as the pump is OK. You can even hear the hissing of the fuel going trough the fuel pressure regulator. I would put the jumper there and try starting with the jumper in. If the car starts OK with the jumper, but not with the relay, then either your relay is wrong or your DME driving transistor responsible of energizing the relay is damaged.

To jump the relay you have to wire a jumper from the relay socket hole corresponding to pin 30 to the hole corresponding to pin 87. Careful not to miss it, as you can damage DME if connect 30 to 85. You can also wire jump some power to fuse F23 from a known good 12 Volts (Vbatt) source.

Guess you have already checked your CPS. No CPS means no spark and no fuel pump.

Javier


Thanks Javier and 632 Regal, I will test tomorrow and get back to both of you.

Eric

[saj3n]

Thanks Javier and 632 Regal, I will test tomorrow and get back to both of you.

Eric

Good Luck!

Had the same problem with mine... Replaced fuel pump, no avail... Nikasil problem, Engine needed to be replaced...

[eelley]

Thanks Javier and 632 Regal, I will test tomorrow and get back to both of you.

Eric


Sorry for the looooong delay in my response. I wanted to record my solution here so it could benefit others. Replacing the crank position sensor fixed the non-start problem.

[Tiger]

Mmm... so much for 'within spec' measurement.