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Starting Problems - Any Ideas?

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    Starting Problems - Any Ideas?

    Hi all,

    After 3 1/2 years off the road and a full nut & bolt rebuild I was looking forward to firing the old girl up again last weekend, seems she has other ideas!

    I've got a spark at all 8 plugs, fuel going into the inlet manifold, starter kicking in, a good battery and good compression on all cylinders.

    When I turn the key she desperately wants to start and run but when I let the key return she dies. I've tried using East Start and the fuel is fresh.

    There's no points as Lumenition is fitted, I'm not running a ballast resistor.

    I'm thinking the likely culprit is in the ignition or LT / HT circuit but have no idea where to start to check things over. I did remove the remains of a simple immobiliser system when I put things back together - used to have 3 wires running to a little black box, 1 from the coil, another to the purple Lumenition wire and a 3rd wire and to an earth. I've now taken the purple Luminition wire directly to the negative side of the coil. Problem is I have no idea how the coil would have been wired up initially, it would appear that there originally may have been 2? wires running to the coil, both look brown & cream in colour and seem to have been connected to each other, not sure if this is to do with Rev Counter which I have been led to believe forms a part of the ignition circuit.

    Any thoughts as to where the problem might lie?

    Much appreciated.

    Iain.
    Last edited by Iain; 8th May 2016, 21:50.

    #2
    Sounds like you have only the wire from the starter solenoid to the + side of the coil and the wire from the ignition switch to the + side of the coil is not connected - side of the coil should have 1 wire from the ign module and the tachometer wire. When you operate the starter you will get a live from the starter so the car will try to start but if the live is not connected from the ign switch when you release the key you loose the live.

    Comment


      #3
      Thanks for your thoughts, I fairly sure myself the problem lies with the wiring to the coil and the ignition switching.
      There are however 2 wires to the positive side as the attached pictures show. Its the negative side I'm not sure about, whilst the purple wire goes to the Lumention module I'm not convinced the other 2 brown/cream wires that are currently bridged together are correct.
      Being stupid I'm also not sure at which point the coil should be live, should the positive side be constantly live or just when the rotor is spinning?
      What would happen if I provided a permanent live feed to the positive side of the coil?
      Attached Files

      Comment


        #4
        You won't get spark at all if you do that. As this is DC, the high volatage is only created when the DC is applied as pulses (which is about half of what the dizzy does). If you are getting a spark at all eigth plugs I have two suggestions:-

        Either the timing is incorrect
        or
        You have no fuel getting the the cylinders.

        I spent ages trying to diagnose an ignition problem only to discover that a quick tap to the petrol pump was what was needed. You have discounted the spark and the fuel so it is almost certainly the timing. The timing is set from cylinder no2 not 1. According to the stagbytriumph web site

        Firing order 1 - 2 - 7 - 8 - 4 - 5 - 6 - 3
        RH bank Nos 1 - 3 - 5 - 7
        LH bank Nos 2 - 4 - 6 - 8

        Cylinders are numbered from the front of the engine.
        Banks are identifed from the rear of the engine.
        Last edited by Pete; 9th May 2016, 13:45.

        Comment


          #5
          Distributor couid be 180 degrees out?
          1975 Mk2 3.0 V8 MOD, new strommies, tubulars & quad exhaust = 166.8 bhp

          Comment


            #6
            Disconnect the + wire from the coil use a test light to check if you have a live when you turn the ign on. The bulb should light when just the ign is on and also when you are cranking with the starter motor. There is no reason I know why you cant run a wire from the + side of the battery to the + side of the coil ( it called hot wiring) the only thing you have to watch is you should have a 6 volt coil so don't run the car too long wired like this. Its a 6 volt coil because the wire from the ign switch to the coil is a resister wire and the wire from the starter is full 12 volt to increase the spark on start up.PS of course you will get a spark from the plugs when cranking as a live is being fed from the starter to the coil
            Last edited by Staggard; 9th May 2016, 15:19.

            Comment


              #7
              is the car mk 1 or 2?
              mk 1 cars coil positive goes through rev counter,
              sounds like you are only getting spark when you cranking

              alan
              Reconditioned Strombergs giving 157.7 bhp. on rolling road msd ignition. petronix.

              Comment


                #8
                Originally posted by stag157.7 View Post
                is the car mk 1 or 2?
                mk 1 cars coil positive goes through rev counter,
                sounds like you are only getting spark when you cranking

                alan
                Alan - does that mean that electronic tachos will not work on an Mk1?

                Comment


                  #9
                  only if you upgrade and change how they are wired
                  although some people have no problems
                  also this is not a new problem on this car
                  it was started after a rebuild in 2011
                  and had a water leak
                  this is from previous postings


                  Hi there,

                  Just a thought but have you tried checking the coil or ballast resistor, if fitted. I had what would appear to be the exact same problem the other weekend after I had fitted a new distributor & associated Luminition bits, car had no power at low revs but ran a dream at idle or on acceleration, Tacho was also all over the place! Existing coil I had was a fairly new Lumintion Mega Spark 4 along with a ballast resistor, popped in a spare coil (Lucas DLB105) I had lying around without the ballast resistor and problem seems to have been cured, should I speak so soon?!!
                  Reconditioned Strombergs giving 157.7 bhp. on rolling road msd ignition. petronix.

                  Comment


                    #10
                    Originally posted by stag157.7 View Post
                    only if you upgrade and change how they are wired
                    although some people have no problems
                    also this is not a new problem on this car
                    it was started after a rebuild in 2011
                    and had a water leak
                    this is from previous postings


                    Hi there,

                    Just a thought but have you tried checking the coil or ballast resistor, if fitted. I had what would appear to be the exact same problem the other weekend after I had fitted a new distributor & associated Luminition bits, car had no power at low revs but ran a dream at idle or on acceleration, Tacho was also all over the place! Existing coil I had was a fairly new Lumintion Mega Spark 4 along with a ballast resistor, popped in a spare coil (Lucas DLB105) I had lying around without the ballast resistor and problem seems to have been cured, should I speak so soon?!!
                    also
                    Coolant Leak

                    After 9 months off the road eventually managed to gather enough parts / funds yesterday to fire up recently rebuilt engine only to find coolant working its way up the thread of No2 Cylinder Head stud and seeping out from the inside of the nut. The original advice given to me by the garage that built the engine up was that it should seal itself but after warming up it continues. Anyone got any ideas what would cause this and more importantly how to cure it? This cars starting to do my head in!!!
                    Reconditioned Strombergs giving 157.7 bhp. on rolling road msd ignition. petronix.

                    Comment


                      #11
                      Hi all, thanks for all your thoughts.

                      1st prize geos to Staggard - thank you for your suggestion, with no apparent live at the coil I connected a wire directly from the battery to the positive side of the coil and hey presto she fired back into life once more confirming my suspicion that the fault was in the ignition circuit. Whilst this does not fix things it does prove everything else is fine (other than the rev counter which is not working).

                      Now all I need to do is work out where the fault lies.

                      Being a Mk1 I believe both problems will be connected.

                      Any thought on where to start next in order to cure the problem would be appreciated.

                      Comment


                        #12
                        Hi normally a Mk 1 has a separate ballast resistor, by the look of your photos you have two wires that are joined together that are connected to the + side of the coil that sort of denotes a MK 1.5 or a Mk 2 anyway one of those should be White & yellow which comes from the starter to supply a live to the coil under cranking I think we have now established that working ok. The wire that is joined to it should be pink & white which ( is a resistor wire) then it turns to white and connects to the ignition switch. If I remember correctly it shares a terminal on the back of the fuse block on the non fused side of the wiper motor fuse. So unless you have a ignition switch failure then I would think that you have a poor connection somewhere along the way from the ignition switch to the coil. I am not too sure what's going on with tachometer wiring but you should have only two wires on the - side of the coil one from your Lumination module ( which you have) and the other White & slate grey from your tachometer. I hope some of this might help you solve your problems.

                        Comment


                          #13
                          Do you have a 6v or 12v coil? The coil looks newish and if it is a 12v coil for non ballasted systems it will not provide much of a spark witha ballast resistor in series. On a mk2 this is hidden as a piece of resistance wird in the loom, so even though you can not see one it is there.

                          I would check first that you have a supply to coil when the ignition is on and you are NOT cranking the engine. With the two wires disconected and the ignition on you should have battery volts on the wire (12.7v ish). Then reconnect the wire and earth the othr side of the coil. If the voltage on the positive side drops significantly then you have the ballasted resistance built into the wiring loom as per a mk2 and need a ballastd coil. WARNING, do not leave power connected for longdr than necessary as there is the possibility of ovdrheatinv the coil. You will be ok for 30 seconds or so and probably longer but be as quick as you can.

                          Roger
                          White TV8 BW35 no mods and now a Dolly Sprint to keep it company
                          So many cars, so little time!

                          Comment


                            #14
                            Don't forget the Mk1 coil+ feed goes through the inductive loop on the tacho....

                            Does anyone see the connection? pun intended

                            Comment


                              #15
                              Originally posted by kryten View Post
                              Don't forget the Mk1 coil+ feed goes through the inductive loop on the tacho....

                              Does anyone see the connection? pun intended
                              I assume that as the car has been restored the tacho connections could have been disturbed and if so this could interrupt the running supply yo the coil. This would be picked up by checking the coil has a supply with just the ignition on and not cranking as per post 13.

                              Roger
                              White TV8 BW35 no mods and now a Dolly Sprint to keep it company
                              So many cars, so little time!

                              Comment

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