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'88 325is M20 - died at idle, now cranks but no start

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    '88 325is M20 - died at idle, now cranks but no start

    OK I searched around but wanted to post here and see if anyone has a list of things to check on the car.

    Background:
    - rebuilt top end
    - new timing belt/water pump
    - new plugs, wires, and crank position sensor
    - new VDO fuel pump

    Have put a couple thousand miles on the car with no issues. No CEL or anything, has been running great. Yesterday on the way to work at a stop light, car was idling like normal and suddenly died. Cranked and cranked and would not fire. Pushed to a parking lot and cranked, started, and died again. Now it cranks endlessly.

    My first guess is fuel filter or maybe a pump-relay? I don't hear the pump click on or prime or anything when I turn the key on.

    Any tips on things to check would be great, will be playing with it tomorrow.

    Thanks!
    Last edited by randomsv650; 10-16-2012, 03:32 PM.
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    #2
    The fuel pump only runs when the DME sees timing data from a rotating engine, it does not prime when the ignition is switched on. Tee a gauge into the the supply line to the fuel rail and see if you have normal pressure when cranking the engine. If not check the fuel pump relay and fuse before replacing the pump.
    The car makes it possible, but the driver makes it happen.
    Jim Levie, Huntsville, AL

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      #3
      Pump relay and fuse...wondered about that. Seems odd it just stalled when running. Ill have to grab a fuel pressure gauge and try that. Fuse/relays should be cheap so maybe ill try them first.
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        #4
        Narrowed it down to no spark today. Tested the ignition coil and it seems bad, measured .30 ohms pos to neg and then 5.62 from the center plug to neg. book shows it should be .82 an 8.00 so I'm hoping the coil is it.
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          #5
          Check the CPS while you are at it.
          2006 GMC Sierra 2500HD 4WD LBZ/Allison
          2002 BMW M3 Alpinweiß/Black
          1999 323i GTS2 Alpinweiß
          1995 M3 Dakargelb/Black
          - S50B32/S6S420G/3.91
          1990 325is Brilliantrot/Tan
          1989 M3 Alpinweiß/Black

          Hers: 1996 Porsche 911 Turbo Black/Black
          Hers: 1988 325iX Coupe Diamantschwartz/Black 5spd

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            #6
            Originally posted by nrubenstein View Post
            Check the CPS while you are at it.
            Yeah the coil didnt do it, though the one i had must have been on its way out, the new ones measurements are well within spec.

            I checked the CPS, book states it should read 515-525 ohms between points 1 and 2. This one isnt a year old, but is only reading 507 ohms. So thats suspect.

            But also found that I am not getting 12v to the ignition coil. I have 12v up to the little battery connections under the hood (that lead from the battery in the trunk). The ignition coil is showing at 8v+- with key on, and then drops to 4v +- when we start cranking the car over.

            Any ideas?
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              #7
              The ignition coil is powered by the ignition switch via C101. What you are seeing suggests a high resistance in that circuit. Start at coil and trace back to the switch to find the problem.

              Note: You must measure the coil power lead from the coil to ground. Not to the coil negative lead.
              The car makes it possible, but the driver makes it happen.
              Jim Levie, Huntsville, AL

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                #8
                ^ I've had that problem with a flaky contact in the ignition switch. My car would just randomly die while driving, then when I'd go to restart it I wouldn't hear all the regular noises I usually hear when I turn the key to the "ON" position. I'd sit there turning the key on and off until that contact would hit. Sometimes it'd take quite a few tries.

                However seeing as though you just changed the CPS, I'd be suspicious of that as well.

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                  #9
                  Originally posted by jlevie View Post
                  The ignition coil is powered by the ignition switch via C101. What you are seeing suggests a high resistance in that circuit. Start at coil and trace back to the switch to find the problem.

                  Note: You must measure the coil power lead from the coil to ground. Not to the coil negative lead.
                  Ok, good points to check, ill look into that. And yes when we checked the coil it was from the coil power lead to a ground on the car, not the neg part on the coil.


                  Originally posted by Bullet Ride View Post
                  ^ I've had that problem with a flaky contact in the ignition switch. My car would just randomly die while driving, then when I'd go to restart it I wouldn't hear all the regular noises I usually hear when I turn the key to the "ON" position. I'd sit there turning the key on and off until that contact would hit. Sometimes it'd take quite a few tries.

                  However seeing as though you just changed the CPS, I'd be suspicious of that as well.
                  In the ignition/key switch itself? I was suspicions of something like that but the fact that it died at a stand still has me wondering. It did start again once (after i pushed it) and died suddenly and hasn't started sense.

                  What about he readings from the CPS? From my understanding if they are out of spec at all they need to be replaced. Im thinking i need to just do the CPS and dist/rotor anyways. Although the CPS i put on when we did the rebuild
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                    #10
                    just a useful link my father found, some good info. Will need to read through this a few times but it's a big help just understanding how the system works.

                    http://www.e30zone.net/e30zonewiki/index.php/Ignition
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                      #11
                      Great information
                      Thanks
                      Barry

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                        #12
                        OK so i am back from vacation (car died a few days before we left, naturally) and am planning on tackling this issue tomorrow.

                        Things I need to check:
                        - CPS (already tested, suspicious of it)
                        - Distributor (and associating bits)
                        - ECU
                        - Main relay
                        - Ignition switch

                        New stuff:
                        - Plugs
                        - Plug wires
                        - Ignition coils

                        I have the clymer, need a bentley really, but and fairly certain i can test the other stuff Any other stuff to check or tips to check them?
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                          #13
                          i dont know much but i would check the icv

                          Goodluck!

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                            #14
                            Originally posted by M3/e30fanatic View Post
                            i dont know much but i would check the icv

                            Goodluck!
                            ICV works, buzzes as im told it should. Also swapped with another know to be working used one, still same result
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                              #15
                              So i popped in (from a running car of a friends) another ECU and Crank sensor. Same result. Still no spark.

                              Ignition switch? Distributor/rotor? Main relay?

                              Anyone else have some tips?
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