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E28 (1982 - 1988)

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  #1  
Old 08-03-2010, 12:51 PM
ryangschultz ryangschultz is offline
RyanGSchultz
Location: New York
 
Join Date: Aug 2010
Posts: 12
Mein Auto: 1981 528i, 2004 Mini Coop
1981 528i Starting/Running Problem

I own a 1981 528i BMW. It's been running great and I have done a lot of electrical and mechanical work on it. But now, all of the sudden, it is having an intermittent starting problem. I just replaced the fuel filter because I thought that may be the issue and I had never replaced it, but the issue is still there.

Sometimes the car will start right up, other times it will turn over but never start. After replacing the fuel filter it will not sometimes start but then stall after a second or two. Could it be an intermittent electrical problem or another fuel problem or what? I don't think it's the pump because the car will start and run, just not every turn of the key. Please help!
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  #2  
Old 08-03-2010, 04:44 PM
catso's Avatar
catso catso is offline
catso
Location: Chicago
 
Join Date: Dec 2009
Posts: 2,989
Mein Auto: 2000 323i, 1988 528e
Quote:
Originally Posted by ryangschultz View Post
I own a 1981 528i BMW. It's been running great and I have done a lot of electrical and mechanical work on it. But now, all of the sudden, it is having an intermittent starting problem. I just replaced the fuel filter because I thought that may be the issue and I had never replaced it, but the issue is still there.

Sometimes the car will start right up, other times it will turn over but never start. After replacing the fuel filter it will not sometimes start but then stall after a second or two. Could it be an intermittent electrical problem or another fuel problem or what? I don't think it's the pump because the car will start and run, just not every turn of the key. Please help!
Maybe the fuel pump relay or some other electrical problem? See if you're getting fuel pressure when the problem occurs. The horn and fuel pump relays are the same, switch the two. Older cars are prone to electrical issues. Check the battery and ground connections real well and examine the fuses real carefully. I saw someone was selling a ceramic and copper fuse replacement kit for $5. Much better than plastic fuses.
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  #3  
Old 08-03-2010, 05:21 PM
ryangschultz ryangschultz is offline
RyanGSchultz
Location: New York
 
Join Date: Aug 2010
Posts: 12
Mein Auto: 1981 528i, 2004 Mini Coop
Catso,

Well the fuel pump relay is actually just a fuse, so I can't switch the horn relay and fuel pump relay. But all the fuses are good. I believe I am getting fuel pressure as well because every tenth start or so the car will start and run and I can drive it around just fine until I shut it off, then it has troubles starting again. Any other ideas? I mean I've replaced all the electronics recently, I even put high performance ignition wires in it and all the spark plugs look great too.
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  #4  
Old 08-03-2010, 05:32 PM
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catso catso is offline
catso
Location: Chicago
 
Join Date: Dec 2009
Posts: 2,989
Mein Auto: 2000 323i, 1988 528e
Quote:
Originally Posted by ryangschultz View Post
Catso,

Well the fuel pump relay is actually just a fuse, so I can't switch the horn relay and fuel pump relay. But all the fuses are good. I believe I am getting fuel pressure as well because every tenth start or so the car will start and run and I can drive it around just fine until I shut it off, then it has troubles starting again. Any other ideas? I mean I've replaced all the electronics recently, I even put high performance ignition wires in it and all the spark plugs look great too.
Sorry, I forgot you have an E12. The systems change from model to model. Cranshaft position sensor maybe? Did you clean out the throttle body real well?
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  #5  
Old 08-03-2010, 07:41 PM
ryangschultz ryangschultz is offline
RyanGSchultz
Location: New York
 
Join Date: Aug 2010
Posts: 12
Mein Auto: 1981 528i, 2004 Mini Coop
Well I just dropped the car off to a friend of mine, he's a certified BMW mechanic so he's going to mess with it and get it running because I don't have the time or the patience. I'll let you know what the problem was though, thanks for your help.
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  #6  
Old 08-04-2010, 10:09 PM
edgarcalderon edgarcalderon is offline
Child of God
Location: Los Angeles, CA
 
Join Date: Aug 2010
Posts: 6
Mein Auto: 1981 BMW 528I
I have the same car, same problem few years ago. You need to change the Combination Relay (fuel pump relay). The relay is not an ordinary fuse, it cost around $125 at the dealer.

Last edited by edgarcalderon; 08-08-2010 at 01:00 AM.
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  #7  
Old 08-05-2010, 03:26 PM
ryangschultz ryangschultz is offline
RyanGSchultz
Location: New York
 
Join Date: Aug 2010
Posts: 12
Mein Auto: 1981 528i, 2004 Mini Coop
Wow thank you very much for the info, my car is with my mechanic now so I just passed along the information to him. He can't work on it until Sunday but hopefully that's all it is so it's an easy fix, just kind of pricey. Thanks for the help.
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  #8  
Old 08-05-2010, 03:41 PM
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catso catso is offline
catso
Location: Chicago
 
Join Date: Dec 2009
Posts: 2,989
Mein Auto: 2000 323i, 1988 528e
Quote:
Originally Posted by ryangschultz View Post
Wow thank you very much for the info, my car is with my mechanic now so I just passed along the information to him. He can't work on it until Sunday but hopefully that's all it is so it's an easy fix, just kind of pricey. Thanks for the help.
Look for someone parting out a similar car or maybe in a junkyard? www.car-parts.com is a comprehensive list of junkyards all across the U.S.
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  #9  
Old 08-05-2010, 05:47 PM
edgarcalderon edgarcalderon is offline
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Location: Los Angeles, CA
 
Join Date: Aug 2010
Posts: 6
Mein Auto: 1981 BMW 528I
The BMW part number is 13631272131, called Combination Relay (fuel pump relay), price $125 plus tax. Part location behind the bracket that holds the water reservoir and right above the break fluid reservoir. It's a small box, 1 inch in depth, 2 inches wide, and 2 inches lenght. The bottom of the unit has two openings for inserts (cables are attched here).

Last edited by edgarcalderon; 08-08-2010 at 01:01 AM.
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  #10  
Old 08-05-2010, 06:20 PM
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catso catso is offline
catso
Location: Chicago
 
Join Date: Dec 2009
Posts: 2,989
Mein Auto: 2000 323i, 1988 528e
Quote:
Originally Posted by edgarcalderon View Post
The BMW part number is 13631272131 and is called Combination relay (fuel pump relay), price is $132.90 plus tax. The exact part location is behind the bracket that holds the water reservoir and right above the break fluid reservoir. It's a small box, 1 inch in depth, 2 inches wide, and 2 inches lenght. The bottom of the unit has two openings for inserts (cables are attched here). Enjoy your classic car.
AutohausAz has the part for $50.15 shipped.
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  #11  
Old 08-05-2010, 07:06 PM
ryangschultz ryangschultz is offline
RyanGSchultz
Location: New York
 
Join Date: Aug 2010
Posts: 12
Mein Auto: 1981 528i, 2004 Mini Coop
Thanks a lot guys, I'll talk to my mechanic and see if he can pinpoint the problem just to make sure that's it. Then i'll buy it install it and hopefully I'll be crusin' again!
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  #12  
Old 08-05-2010, 07:19 PM
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catso catso is offline
catso
Location: Chicago
 
Join Date: Dec 2009
Posts: 2,989
Mein Auto: 2000 323i, 1988 528e
Quote:
Originally Posted by ryangschultz View Post
Thanks a lot guys, I'll talk to my mechanic and see if he can pinpoint the problem just to make sure that's it. Then i'll buy it install it and hopefully I'll be crusin' again!
Verify the relay is actually the one you're looking for. Here's a picture with connector details from their website.
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  #13  
Old 08-05-2010, 07:53 PM
edgarcalderon edgarcalderon is offline
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Location: Los Angeles, CA
 
Join Date: Aug 2010
Posts: 6
Mein Auto: 1981 BMW 528I
Correct your are

That is the right part, good picture!
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  #14  
Old 08-18-2010, 04:13 PM
ryangschultz ryangschultz is offline
RyanGSchultz
Location: New York
 
Join Date: Aug 2010
Posts: 12
Mein Auto: 1981 528i, 2004 Mini Coop
Alright, just got the car back and it's starting and running great! I had my mechanic friend diagnose it and it was the fuel pump relay, there was also some loose or broken connection he fixed under the fuse box or something too. Got the relay from bavauto for $55. Thanks a ton for the help guys!
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