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E34 (1989 - 1995)

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  #1  
Old 08-26-2019, 01:26 AM
jbgh jbgh is offline
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Mein Auto: E34 M50B25TU
1995 M50 No Start (but close!)

Hey pals hate to make a no start thread but I'm looking for some advice. Put a new battery in 2 days ago (it was dead flat, I hadn't driven in a couple of months) and car started fine after.
Yesterday no start. It cranks and sounds like it's almost going to start.

My coil packs are getting voltage. Coil pack resistance is 0.9 ohms across the board.

I put a few litres of fuel in just in case...

I think next thing to check is the crankshaft position sensor resistance, but it seems impossible to find the plug. Can someone point me in the right direction?

Otherwise am I on the right track?

Cheers

P.S. there's no stomp test on Australian E34s
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  #2  
Old 08-26-2019, 04:53 AM
jbgh jbgh is offline
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Lil update, it kinda starts and then dies if I REALLY crank it. Fuel pump or filter? Or crank position sensor?
Cheers for looking pals
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  #3  
Old 08-26-2019, 07:19 AM
BMR_LVR's Avatar
BMR_LVR BMR_LVR is offline
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Location: Asheboro, NC
 
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Mein Auto: 1992 525i
It could very well be the fuel pump. If you spray a little starter fluid in the intake when cranking the engine over and it starts and runs for a few seconds on the starter fluid (don't keep it running more than 2-3 seconds - the starter fluid is hard on the internals), then your CPS is good and you have a fuel delivery problem. If that is the case, it could be the fuel pump fuse, the fuel pump relay or the pump itself. I usually check in that order.

Definitely look at the CPS resistance. The plug is tucked under the intake manifold. Trace the wire from the CPS on the crank pulley and follow it up over the front of the valve cover down under the intake. It's a little difficult to get to, but you can do it. It also helps to slide the connector out of its holder which makes it easier to get it apart and get to the posts.

Hope this helps.
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Calypso Red 1992 525i with 225K miles

1991 735i - Sold
1992 525i - Sold
1995 325is - Sold
2000 528i - Sold

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  #4  
Old 08-26-2019, 07:32 AM
jbgh jbgh is offline
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Quote:
Originally Posted by BMR_LVR View Post
It could very well be the fuel pump. If you spray a little starter fluid in the intake when cranking the engine over and it starts and runs for a few seconds on the starter fluid (don't keep it running more than 2-3 seconds - the starter fluid is hard on the internals), then your CPS is good and you have a fuel delivery problem. If that is the case, it could be the fuel pump fuse, the fuel pump relay or the pump itself. I usually check in that order.

Definitely look at the CPS resistance. The plug is tucked under the intake manifold. Trace the wire from the CPS on the crank pulley and follow it up over the front of the valve cover down under the intake. It's a little difficult to get to, but you can do it. It also helps to slide the connector out of its holder which makes it easier to get it apart and get to the posts.

Hope this helps.
Very helpful thanks, I'll grab some starter fluid in the morning and see what happens.

Do I need to remove the intake manifold or anything else to get to the CPS plug?

Fuel pump fuse was the first thing I checked, but that's as far as I got on fuel delivery. Just opened up that Bentley manual chapter so I've got some things to try tomorrow.

Edit: Could it be a clogged fuel filter? Just realised I haven't changed it in recent memory.
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1995 525i Auto with 275K km
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Last edited by jbgh; 08-26-2019 at 07:33 AM. Reason: edit
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  #5  
Old 08-26-2019, 08:01 AM
BMR_LVR's Avatar
BMR_LVR BMR_LVR is offline
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Location: Asheboro, NC
 
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Sorry for the late reply. Having some troubles with my computer. Having to respond from my phone with the app.

You do not need to remove the intake manifold in order to get to the CPS plug. Itís just pretty tight in there. Just note that the CPS resistance reading listed in the Bentley manual is not correct. I canít recall the exact numbers at the moment, and my computer is giving me problems so I canít look it up. Search oldthreads for the correct CPS Reading. In fact, it may be in my sticky thread at the top. Good luck.




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__________________
Most problems are usually something simple !

Quote:
Originally Posted by noego View Post
It's Deja Poo - as in, I've heard this **** before.
Steve

Calypso Red 1992 525i with 225K miles

1991 735i - Sold
1992 525i - Sold
1995 325is - Sold
2000 528i - Sold

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  #6  
Old 08-26-2019, 08:37 AM
BMR_LVR's Avatar
BMR_LVR BMR_LVR is offline
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Location: Asheboro, NC
 
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Got my computer back up. Here's some info from an old post I made:

"Bentley page 120-5 covers it.

The magnetic end is bolted on the engine block just above the toothed wheel on the crankshaft. if you were facing the engine, the CPS is located at about the 10:00 o'clock position. You have to trace the wire to the terminal located underneath the intake manifold. It is a lot easier to get to if you remove the alternator cooling ductwork.

Unplug the CPS at the terminal. Using a digital multi meter on the ohms setting, check for resistance at terminals 1 and 2.

*** Here is an important note ***: The Bentley manual had a misprint on the resistance values. It states that it should be 1280 +/- 10%. This is INCORRECT. The correct reading should be 540 +/- 10%."


Hope this helps.
__________________
Most problems are usually something simple !

Quote:
Originally Posted by noego View Post
It's Deja Poo - as in, I've heard this **** before.
Steve

Calypso Red 1992 525i with 225K miles

1991 735i - Sold
1992 525i - Sold
1995 325is - Sold
2000 528i - Sold

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  #7  
Old 08-26-2019, 08:38 AM
BMR_LVR's Avatar
BMR_LVR BMR_LVR is offline
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Location: Asheboro, NC
 
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Mein Auto: 1992 525i
and yes, it can be a clogged fuel filter if it is a fuel delivery problem. Got to get to work now. Good luck.
__________________
Most problems are usually something simple !

Quote:
Originally Posted by noego View Post
It's Deja Poo - as in, I've heard this **** before.
Steve

Calypso Red 1992 525i with 225K miles

1991 735i - Sold
1992 525i - Sold
1995 325is - Sold
2000 528i - Sold

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  #8  
Old 08-26-2019, 10:46 PM
jbgh jbgh is offline
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Location: Melbourne, Australia
 
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Mein Auto: E34 M50B25TU
Thanks for all the replies!
I can feel the fuel pump relay clicking, but I bypassed it to be sure. Jumpered pins 30 & 87.
Couldn't hear the fuel pump, so I unplugged it and checked for voltage. No voltage across pin 4 & 5.
Am I missing something or is that very strange?

Edit: I guess the next logical thing to check is that there's voltage at pin 30 of the fuel pump relay socket.. Bentley manual says there should always be battery voltage there. Nothing on mine though.
Where to next?
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1995 525i Auto with 275K km
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Last edited by jbgh; 08-27-2019 at 12:09 AM. Reason: edit
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  #9  
Old 08-27-2019, 09:14 PM
BMR_LVR's Avatar
BMR_LVR BMR_LVR is offline
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Location: Asheboro, NC
 
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Mein Auto: 1992 525i
Unfortunately, I'm very weak with electronics. Did you have pins 30 and 87 jumpered when you checked for voltage at the fuel pump connector? If so, then you should have voltage at the connector assuming you jumpered the correct pins at the relay. If I were in your shoes, I would apply 12 volts directly to the fuel pump to see if it runs. If it does, you may have a wiring problem, but that is very rare.

Did you check the CPS? If it is bad, the pump will not engage when the engine is cranked over because the computer is not getting signal from the CPS indicating crank rotation.

Sorry I can't be more help in the electronics aspect of this problem. Good luck.
__________________
Most problems are usually something simple !

Quote:
Originally Posted by noego View Post
It's Deja Poo - as in, I've heard this **** before.
Steve

Calypso Red 1992 525i with 225K miles

1991 735i - Sold
1992 525i - Sold
1995 325is - Sold
2000 528i - Sold

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  #10  
Old 08-28-2019, 12:11 AM
jbgh jbgh is offline
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Location: Melbourne, Australia
 
Join Date: Apr 2015
Posts: 6
Mein Auto: E34 M50B25TU
Quote:
Originally Posted by BMR_LVR View Post
Did you have pins 30 and 87 jumpered when you checked for voltage at the fuel pump connector? If so, then you should have voltage at the connector assuming you jumpered the correct pins at the relay. If I were in your shoes, I would apply 12 volts directly to the fuel pump to see if it runs. If it does, you may have a wiring problem, but that is very rare.

Did you check the CPS? If it is bad, the pump will not engage when the engine is cranked over because the computer is not getting signal from the CPS indicating crank rotation.
I haven't checked the CPS yet.
I jumpered pins 30 and 87 at the fuel pump relay socket, and had no voltage at the pump.
Then I checked pin 30 at the relay socket, and didn't have voltage there. I guess I need to find out why battery voltage isn't getting to the relay socket. Maybe someone else can chime in with a suggestion? I don't believe a bad CPS would prevent the socket getting voltage, but I may be wrong?

Thanks again for reading and for your suggestions, it's much appreciated. I'm quite enjoying finding my way and learning, I'm confident I'll get to the root of the problem eventually!
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1995 525i Auto with 275K km
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  #11  
Old 09-02-2019, 09:47 PM
jbgh jbgh is offline
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Location: Melbourne, Australia
 
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Mein Auto: E34 M50B25TU
Lil update pals. I jumpered some power to the fuel pump relay (pin 87) and gave it a go.
Made a loud bang noise, and had smoke out of the air filter.

I'd like to think it's just because I sprayed too much starter fluid in the throttle body last time I tried it (a week ago) but I gave myself a fright and I'm a bit worried to continue.

I pulled a spark plug to see if the cylinders were flooded, but it's dry. I had a little bit of oil though, so valve cover gasket might be next.

It might be time to give up and get it towed to the mechanic I think!
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1995 525i Auto with 275K km
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1995, 525i, 6 cylinder, bmw, crank, e34, m50, start


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