Car cranks but doesn't fire - NCRS Discussion Boards

Car cranks but doesn't fire

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  • Stephen L.
    Extremely Frequent Poster
    • May 31, 1984
    • 3156

    #16
    Re: Car cranks but doesn't fire

    Michael, did you do the test for spark? (Remove the coil wire and touch/hold close to ground while cranking?)

    I agree, if you didn't remove/replace the distributor since you ran the engine then the timing should NOT be an issue. I assume you didn't touch the spark plug wires on the distributor cap either and you checked the firing order, if you did

    If all this doesn't solve your problem then replacing the points, capacitor, and coil may be your next step.

    Comment

    • Michael L.
      Extremely Frequent Poster
      • December 15, 2006
      • 1390

      #17
      Re: Car cranks but doesn't fire

      Correct I did not remove wires. I haven't checked for spark that way yet that will be my next step. If I do that and get spark but I do not get spark at the plug wires then the problem is definitely in the distributor, correct?

      Comment

      • Stephen L.
        Extremely Frequent Poster
        • May 31, 1984
        • 3156

        #18
        Re: Car cranks but doesn't fire

        If you have spark at the coil wire to ground, there isn't much left, except the distributor cap, rotor and the spark plug wires themselves..... Check to make sure the carbon pin inside the cap is in place and the rotor has the metal center intact along with the springy metal piece.

        You mentioned early on that you readjusted the points because they appeared to not open. I had a set of points fail because the phenolic rub block, that is part of the points assy, came loose and fell off resulting in the points not opening at all..... again the spark check mentioned earlier will prove this section to be ok, if you have spark.

        Comment

        • Michael L.
          Extremely Frequent Poster
          • December 15, 2006
          • 1390

          #19
          Re: Car cranks but doesn't fire

          It looks to me that the rub block is still in place. I can see it and the points now open and close without issue. I will check the spark at both the coil and the plug wires and report back.

          Comment

          • William F.
            Extremely Frequent Poster
            • June 9, 2009
            • 1363

            #20
            Re: Car cranks but doesn't fire

            Please let us know how this turns out.

            Comment

            • Michael L.
              Extremely Frequent Poster
              • December 15, 2006
              • 1390

              #21
              Re: Car cranks but doesn't fire

              OK so I checked for spark from the coil wire and I get nothing. I also checked for power at the coil while cranking and I get approx. 12V with the key in the on position and approx. 9V with the key in the start position. I'm thinking this has narrowed it down to a bad coil? I'm going to wire up a spare I have here and see if that works.

              Comment

              • Stephen L.
                Extremely Frequent Poster
                • May 31, 1984
                • 3156

                #22
                Re: Car cranks but doesn't fire

                If you have a dwell meter, connect it and see if you have a dwell reading while cranking the engine. That will tell you the points are opening/closing and the circuit is functioning. If you get a reading then the only item left is the coil. If you don't get a reading, then the points, condenser, and associated wiring is the culprit. Make sure the wire from the points to the coil is NOT touching ground or "open". (No continuity of the wire itself)

                Hang in there! You are getting close to the solution.....

                Comment

                • Larry M.
                  Extremely Frequent Poster
                  • January 1, 1992
                  • 2688

                  #23
                  Re: Car cranks but doesn't fire

                  The 12 volt test light I mentioned earlier and the dwell meter will provide the same/similar data: whether the points and condenser and distributor are functioning correctly.

                  I was hoping this would have been checked by now.....since it is a very easy test. But at least it should be now.

                  Larry

                  Comment

                  • Michael L.
                    Extremely Frequent Poster
                    • December 15, 2006
                    • 1390

                    #24
                    Re: Car cranks but doesn't fire

                    I don't think I have a dwell meter anymore but I obviously need to get one. I was working on the coil and noticed something on it I hadn't seen before. The coil has a sticker on it that says: "for transistor ignition". I don't have transistor ignition. Is this coil compatible? I switched out the coil with an old coil I had lying around and I was able to get a single spark out of it when I turned the key on. I connected it to the distributor and when I cranked the engine I got the slightest sense that the car wanted to cough a little but then nothing. Still cranks and does nothing else. I then replaced one of the spark plug wires with a spare and connected a spark plug to it and didn't get an spark that I could see. Does a spark plug have to be grounded to fire?

                    Comment

                    • Michael L.
                      Extremely Frequent Poster
                      • December 15, 2006
                      • 1390

                      #25
                      Re: Car cranks but doesn't fire

                      GOT IT STARTED!!!! I was checking out the points and I forgot the key was on and I got a little spark from the points. So I filed them down and I changed the condenser and it fired up! I still just need to figure out if the coil I got is compatible with a non-transistor system if anyone knows. Thanks for all the helpful hints and tips.

                      Mike

                      Comment

                      • Stephen L.
                        Extremely Frequent Poster
                        • May 31, 1984
                        • 3156

                        #26
                        Re: Car cranks but doesn't fire

                        Congratulations... The coil may draw a little more current (lower winding resistance) which may shorten the life of the points.

                        If you had to "file the points" assuming they were new when you rebuilt the engine and did not run it much, someone left the key on..... without the engine running......

                        Comment

                        • Michael L.
                          Extremely Frequent Poster
                          • December 15, 2006
                          • 1390

                          #27

                          Comment

                          • Stephen L.
                            Extremely Frequent Poster
                            • May 31, 1984
                            • 3156

                            #28
                            Re: Car cranks but doesn't fire

                            First: Get the dwell set correctly. Then get the timing set. You may be amazed.....

                            Other potential problems:
                            plug wires in poor condition; very high resistance or poor insulation allowing arcing to ground. If the wires are exposed, run the engine in the dark and see if there is some "stray" sparking from the wires...... Check the resistance with an ohm meter.
                            Cracked distributor cap
                            Rotor specs (metal piece too short)
                            Incorrect gap on the plugs or dirty (Carbon build-up)
                            Carb set up problems.... idle mixture etc.

                            Comment

                            • William F.
                              Extremely Frequent Poster
                              • June 9, 2009
                              • 1363

                              #29
                              Re: Car cranks but doesn't fire

                              You're supposed to get full 12 v when cranking then should drop back to 9 when running. Your're getting the opposite unless you stated it backwards. 12V running will burn points. If you're not getting 12V cranking, could be a corroded solenoid (I had this problem once) or incorrect wiring at solenoid.

                              Comment

                              • Mark E.
                                Extremely Frequent Poster
                                • April 1, 1993
                                • 4533

                                #30
                                Re: Car cranks but doesn't fire

                                Now that you got it started and made sure the coil is getting the proper voltage during cranking and while running, go ahead and install new contact points. Yes, burned and pitted points can be filed flat to get you going for awhile. But the real fix is new points.

                                Contacts are actually not flat; they have a large radius (sort of like a valve lifter's base) for proper operation. Also, the contact surface is a thin layer of a hard metal (often tungsten) that resists pitting and heat, and better maintains a mirror like finish. The radius, surface hardness and finish are there to meet specified performance and longevity specs. These qualities are degraded or removed by filing.

                                Filing points has been done for generations, but it's really a stop-gap fix that won't last and doesn't provide the best performance.
                                Last edited by Mark E.; June 17, 2020, 01:42 PM.
                                Mark Edmondson
                                Dallas, Texas
                                Texas Chapter

                                1970 Coupe, Donnybrooke Green, Light Saddle LS5 M20 A31 C60 G81 N37 N40 UA6 U79
                                1993 Coupe, 40th Anniversary, 6-speed, PEG 1, FX3, CD, Bronze Top

                                Comment

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