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    Crank no start please help

    I need some help with my ‘85 e30 m10 I’ve had the car for a couple years and finally got a chance to mess with it. I have verified that spark and timing are good and with brake cleaner the car will start so I know I have a fuel problem. I have the fuel pump hardwired with a fuse and relay and can turn on but when I pulled the injectors there’s no spray and the fuel is getting to the rail. Testing the stock wiring harness Im getting no power to It and I have an e30 book and the power to the injectors comes from the idle speed stabilization relay and according to the book it’s a 9 pin relay but mine in a 6 pin so I’m lost here I bought a used one and coming in soon but I’m not sure that’s my problem because my fuel pump relay isn’t giving power to the stock wiring harness that’s why I hardwired it. I’m not the best at wiring but understand it Can anyone with m10 L jetronic help me. Last piece of info there were 2 ecus in the car when I bought it but to me they both work but also don’t know how to test it. According to the book pin 9 and 13 to ecu should have power when cranking but I don’t have that I’m wondering if that’s coming from the idle stabilization relay? Please help I really don’t want to rip out the engine and throw in something else I just want this engine to run and drive.

    #2
    When you say two ECUs, are you referring to the DME and Idle Control Module?

    I'd have to refer to my service data, but I do have a hard copy of the ETM for M10 e30s, so can get you any diagrams you will need (if they're not available through the wedophones links). Do you have power at the DME/ECU? It seems to me that it isn't doing its job at all.... the ignition system on these is run on a standalone ignition module, so its theoretically possible to have spark without a functional DME. I would start there - it is also possible that the DME is not being informed that the engine is actually cranking.

    It has been a number of years since I worked w/L-Jetronic, but I am happy to help you work through this.
    IMG_0145 by Jonathan Martin, on Flickr

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      #3
      I appreciate you even replying and yeah it had 2 dme’s. And I also had a feeling the ignition ran on a separate system because with the ecm out it still cranks over. Would the idle speed stabilization give power to the ecm as well, I’ve heard of the link wedophones and a little hard to understand where the dme gets power. I see that the fuel pump relay gives power to the injection control module according to what I can see but idk where that’s at and I thought that was the idle stabilization relay. All these names for different things gets confusing what’s what and my fuel pump relay is a 7 pin relay if that helps when I turn to key to ignition I can’t feel the fuel pump relay click so makes me feel that it’s bad

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        #4
        I have an 84 318i, so I have been thru most of these issues. I find that the Bentley manual and the factory BMW manual often have different names for some parts. You need to have an organized approach to a crank/no start issue. So if you have properly timed spark, then it is most likely a fuel issue (no compression, blocked exhaust, etc are rare). For the 7 pin fuel relay to work it needs power (pin 30) and either a crank signal (pin 50) or of a “tach” signal (pin 1). You can “jumper” the pump (30 to 87). If the pump is working properly you should get about 40 psi of fuel to the fuel rail (a clogged fuel filter can impact this). If you get to this point and still are not getting fuel into the cylinder you either are not getting a signal to the injectors or the camshaft isn’t turning. A “noid” light is utilized to check if the injectors are getting a signal to open. The second photo is a switch/fused jumper.
        Click image for larger version

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          #5
          As far as not getting power to 9 and 13 of the ECU, IIRC the Bentley manual pin out diagram is incorrect. Pin 1 should be adjacent to the cable. There is a correct pin out of the connector on a English E30 website.

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            #6
            I believe power for the injectors come from the fuel pump relay (pin 87b). So if you don’t have a working fuel relay or alternatively jumper the injector, you won’t get fuel. The injectors are then triggered by the ECU (called injection control module in the BMW Troubleshooting manual.

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              #7
              Originally posted by Sunnyledge View Post
              . The second photo is a switch/fused jumper.
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              that's brilliant.

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