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7 Series - E38 (1995 - 2001)

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  #1  
Old 10-01-2010, 09:59 AM
greenebmw greenebmw is offline
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97 740i starting issue

Hey there -
New to this site and have a none starting but it cranks just wont start up. Took it to the shop and they said its the fuel pump and filter. With a cost of $800.00 so I got on line and found out it was easy to do so i did it myself. Got it running now its doing the same thing. I am at a loss I checked all fuses and battery all is good. It will start if if continue to mess with it through out the day and can get 5 or six starts out of it but the AM nothing it cranks but still not turning over. What else can I be missing please HELP =P
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  #2  
Old 10-01-2010, 12:52 PM
balance balance is offline
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So you changed the pump and filter, or just the pump? How long ago? Is the CEL on? Have you checked fuel pressure?
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  #3  
Old 10-01-2010, 01:10 PM
greenebmw greenebmw is offline
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I changed both pump an filter 48 hours ago. it was running fine then this AM same thing I can get it to start if i try later in the day. I was told from my shop that it must be the crankshaft position sensor. Does that sound like a good next step?
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  #4  
Old 10-01-2010, 01:11 PM
greenebmw greenebmw is offline
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Not sure what the CEL means sorry
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  #5  
Old 10-01-2010, 01:20 PM
balance balance is offline
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CEL = "Check Engine Light"

If the crank sensor goes bad, it would stop the motor from starting, and another member on this forum stated that it stopped his fuel pump from cutting on as well. It very well could be the cause of your issues.

What I would do is check for spark, do you know how to take a coil off of the motor?
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  #6  
Old 10-01-2010, 01:23 PM
greenebmw greenebmw is offline
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the Check engine light is on I do not know how to check for a spark or take a coil off new to the bimmer site and to bimmers in general .....
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  #7  
Old 10-01-2010, 01:42 PM
balance balance is offline
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If you plan on diagnosing problems that you may run into while owning this car, I would suggest that you pick up an OBD 2 scanner at an auto parts store. I've seen them run anywhere from $25 to $150 for a cheap basic model that will only read codes, but even the cheap model will probably last you forever, and it will be enough to help diagnose most issues you might run into. Not to mention that it is portable and you do not need to be charged to have the car towed to a shop to have the diagnostic codes read.

When the CEL is on, then that means that the computer has detected a fault in the electronic system of your car. It will be alot easier to diagnose if you get a scanner to read what fault code is stored. If the fault code for the Crankshaft Position Sensor (CKS) has been stored in the computer, that that is almost certainly the issue.
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  #8  
Old 10-01-2010, 01:50 PM
greenebmw greenebmw is offline
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Great thank you for your help I was and have been at a loss since this all started I bought the sensor already since the shop is what told me it was the pump and filter only place else I thought was the sensor. the did a diagnostic check on it at the shop but at that time no check engine light was on so it read fine. I wonder if since i changed the pump and filter now it sees its the sensor. Does that sounds right to you/
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  #9  
Old 10-01-2010, 01:57 PM
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It is possible that the computer didn't register the fault until after the car left the shop. Cars are funny in that sometimes two completly different systems will go bad days away from each other, and I wouldn't be surprised if this is one of the cases.

I'm sorry I should have been more clear with my question earlier, but when I asked if the CEL was on, I meant was it on while the car was running? All of the lights should be on when you turn the key, but they should all cut off when the motor actually turns over. Get the car started and see if the CEL is on. If it is, I would use this opportunity to buy a scanner and see what the stored fault code is.
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  #10  
Old 10-01-2010, 01:59 PM
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Also, if you already have the sensor, replacing it wouldn't hurt.
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  #11  
Old 10-01-2010, 02:09 PM
greenebmw greenebmw is offline
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The CEL turns off after it starts do you think I am on the right track with the sensor? Should it test for spark? If so how is that done sorry for all the question just doing it the DIY way shops prices these days are off the hook
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  #12  
Old 10-01-2010, 02:17 PM
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If the CEL is not on when the motor is running, then there are probably no faults stored in the computer. If I had the CKS on hand, I would probably replace it anyway just to see if it fixes the issue. If it does not fix the issue, then I'll tell you how to take out a coil to check for spark.

I have to say though, it is strange that the motor only starts in certain times of the day. Is it really cold in the mornings where you are? When the car starts, does it run rough?
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  #13  
Old 10-01-2010, 02:33 PM
greenebmw greenebmw is offline
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I live in phoenix az so cold its not its like 80 in the morning right now. when it turns over and I go for a spin it rides perfect not rough at all. The filter was full off junk when I replaced it then the car started right up. Then last night I went out after several hours it started right up again. That is why I am like what is the deal could it be the crankshaft senor I really dont know what else i can do. I had the car looked over from front to back at the shop and it checked out fine no errors what so ever. I was very please then now this situation.
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  #14  
Old 10-01-2010, 02:43 PM
balance balance is offline
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Sometimes the crank sensor will not throw a code when it is failing, so try changing that first, and if that fixes it, then great. If that does not fix it, then you will have to check for fuel and spark. But sinse the issue is not constant, and only happens on certain occasions, it may be hard to diagnose.

Change the Crankshaft Position Sensor first and see what happens.
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  #15  
Old 10-01-2010, 02:55 PM
greenebmw greenebmw is offline
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I will and I will let you know if I knock this problem OUT thank you for your help i will keep you posted.
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  #16  
Old 10-03-2010, 11:44 AM
greenebmw greenebmw is offline
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Well I changed the crankshaft sensor still have the same problem any ideas???
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  #17  
Old 10-03-2010, 06:19 PM
balance balance is offline
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Since the problem is intermittent, it will be harder to diagnose.

The next time the car doesn't start, try disconnecting the fuel line by the fuel rail and turn the key to the on position only (don't start the car). If fuel is spurting out of the fuel line, then you can be pretty sure the fuel system is working as it should and the car is not starting for another reason.

If the fuel system seems good then you should move on to checking for spark. Pull off the plastic BMW cover on one side of the motor, take out the two screws to pull out one of the coils, get a string of wire and connect it to ground, and while someone turns the key to start the motor, touch the wire to where the coil touches the spark plug and you should see an arc between the coil and wire.

Only check for fuel and spark when the car will not start, as you will get both spark and fuel when the car is working regularly.
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  #18  
Old 10-04-2010, 09:12 AM
greenebmw greenebmw is offline
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Where do I find the fuel line by the fuel rail? Is this by the filter I got to the spark plug last night however I did not see where the coil is locate sorry this may be two dumb ass questions but as you know I am new to this type of car and well its becoming interesting but stressful = P
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  #19  
Old 10-04-2010, 04:28 PM
balance balance is offline
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There is a black fuel rail that connects the eight fuel injectors to the top of the plastic air intake manifold on top of the motor, you should see this right after you take out the plastic cover on the top of the motor. If you check on the back end of the fuel rail on the driver's side, you will see a rubber line with a clamp on it that you would need to take off to take the fuel line off. If it still has the factory clamp on it, which is not re-useable, you will need to cut the clamp off, and then replace it with another clamp after you re-install the fuel line to the rail.

The coil is the last thing you took out before you got to the spark plug. It is a square piece that has a tube that connects to the head of the spark plug. Also, do not touch the end of the coil that connects to the spark plug while the motor is running or else you will get shocked.
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  #20  
Old 10-04-2010, 05:08 PM
greenebmw greenebmw is offline
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thanks I check for spark and the fuel line this am while it was not turning over. The gas line was not getting pressure so I went to the pump and the pump wasn't turning on. I took it out check the voltage and all was okay i reinstalled it. I then turned the key to start position and heard the pump turn on. Now it seems to be starting fine. My question is what would cause it to now activate in the morning? I checked fuses and all was okay could it be in the ignision switch and it not activating the fuel pump some how? I am stumped
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  #21  
Old 10-04-2010, 05:51 PM
balance balance is offline
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When you took the pump out, did you connect the leads to the battery to get it to run outside of the tank? If you did, was it making any strange noises that sounded like it was on its way out? I know the pump is less than a week old, but I've handled more "brand new" defective parts than I can remember. Also, if you still have the old pump, test that one too.

Sinse it is a fuel issue, and the pump, filter, and crank sensor did not fix it, I would take it back to the shop that told you that it was either the pump, filter, or crank sensor. Especially if you paid them for this diagnosis. Don't call them, just show up with the car, and tell them what you have done so far, and see if they can help.
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