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james merritt
Joined: 02 Mar 2017 Posts: 3
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Posted: Mon Mar 20, 2017 7:40 pm Post subject: Starting issue 103e |
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My 103e has a weird starting problem it will start with a 12v jump start and then runs ok but it won't start with a 6v battery . I've put a new 6 v battery on stripped and cleaned starter motor, new leads all round . Earth straps changed and cleaned . I've blown through the jets . I can't seem to hand crank it either . I'm stumped |
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peter scott
Joined: 18 Dec 2007 Posts: 7126 Location: Edinburgh
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Posted: Mon Mar 20, 2017 9:18 pm Post subject: |
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Hi James,
If it starts with more volts then the problem is in your ignition system. Suspect any new black plastic parts such as rotor arm, distributor top etc. There are quite a few new parts that are not good insulators. try to find old parts (they are properly insulating).
Peter _________________ http://www.nostalgiatech.co.uk
1939 SS Jaguar 2 1/2 litre saloon |
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Paul fairall
Joined: 17 Nov 2016 Posts: 429 Location: North west Kent
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Posted: Mon Mar 20, 2017 9:23 pm Post subject: |
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So it starts with a 12v jump then runs with the 6v battery connected or 12v battery. _________________ 1957 ford popular |
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james merritt
Joined: 02 Mar 2017 Posts: 3
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Posted: Tue Mar 21, 2017 1:10 am Post subject: |
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Runs with 6 v but jumps on 12 volt |
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Peter_L
Joined: 10 Apr 2008 Posts: 2680 Location: New Brunswick. Canada.
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Posted: Tue Mar 21, 2017 2:36 pm Post subject: |
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Did it suddenly develop this problem or did you recently acquire the vehicle with the problem built in. ?
My instinct is 1: A less than good earth return from the engine to the chassis/battery. 2: The coil, could it be 12v ? |
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Paul fairall
Joined: 17 Nov 2016 Posts: 429 Location: North west Kent
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Posted: Tue Mar 21, 2017 8:07 pm Post subject: |
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Does the engine turn on 6v until the battery dies. If so I'm thinking the fuel hasn't had time to reach the carb before the battery dies. With mine I manually pump fuel into the carb with the the rod on the fuel pump. If I don't then it won't start straight off and the battery will die before it fires. I only need to leave it an hour and it requires priming. 12v will turn the engine faster and pump the fuel up quicker. _________________ 1957 ford popular |
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Rene
Joined: 06 Jul 2012 Posts: 125
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Posted: Tue Mar 21, 2017 10:08 pm Post subject: |
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I had the same problem.
The 3 brush dynamo was melted because of a"hanging"cutout.
The startermoter bearings were gone so the starter used too much power and the volts were too low for the ingnition to fire the motor,a 12volt jumpstart takes care of the low volts,when the engine is running the starter is not in use so there are enough volts for the ignition. |
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alanb
Joined: 10 Sep 2012 Posts: 516 Location: Berkshire.
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Posted: Wed Mar 22, 2017 11:56 am Post subject: |
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If you can't hand crank it either the there must be something very tight in or on the engine. Has the engine recently been rebuilt? _________________ old tourer
Morris 8 two seater |
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Peter_L
Joined: 10 Apr 2008 Posts: 2680 Location: New Brunswick. Canada.
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Posted: Wed Mar 22, 2017 12:39 pm Post subject: |
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alanb wrote: | If you can't hand crank it either the there must be something very tight in or on the engine. Has the engine recently been rebuilt? |
I assumed, and perhaps incorrectly, that the reference to "hand cranking" just meant that it wouldn't start on 6v battery if the engine was hand cranked, which could point to coil voltage or fuel pump , as already suggested. |
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Paul fairall
Joined: 17 Nov 2016 Posts: 429 Location: North west Kent
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Posted: Wed Mar 22, 2017 7:46 pm Post subject: |
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alanb wrote: | If you can't hand crank it either the there must be something very tight in or on the engine. Has the engine recently been rebuilt? |
Maybe I'm being thick, but I think he means it doesn't start by hand cranking it. _________________ 1957 ford popular |
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alanb
Joined: 10 Sep 2012 Posts: 516 Location: Berkshire.
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Posted: Wed Mar 22, 2017 9:43 pm Post subject: |
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As it is a mechanical fuel pump and runs ok once started it doesn't look like a fuel problem, if it has the correct 6 volt coil and is connected correctly it should provide enough of a spark from as little as 4.5volts to start it by hand cranking, In the past I have started my Morris useing a 4.8volt lantern battery and hand cranking. _________________ old tourer
Morris 8 two seater |
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Peter_L
Joined: 10 Apr 2008 Posts: 2680 Location: New Brunswick. Canada.
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Posted: Wed Mar 22, 2017 10:05 pm Post subject: |
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alanb wrote: | As it is a mechanical fuel pump and runs ok once started it doesn't look like a fuel problem, if it has the correct 6 volt coil and is connected correctly it should provide enough of a spark from as little as 4.5volts to start it by hand cranking, In the past I have started my Morris useing a 4.8volt lantern battery and hand cranking. |
but.... if it was a 12v coil, the spark wouldn't be that good.
A meter test across the primary. would give a clue. Someone must have an ohms value for 6v and 12v. maybe it is even on Google, I haven't looked yet.
But having said all that, a simple ignition on, crank and view a spark plug would be the start of a logical problem solving route.
Perhaps the rotor shaft is worn and the higher rotational speed of 12v across the starter throws the rotor arm closer to the distributor contacts.
A rule of thumb, petrol vapour plus spark = ignition in the chamber.
So if it runs, then there can't be much wrong with all the other parameters that combine to make a perfect running engine. |
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alanb
Joined: 10 Sep 2012 Posts: 516 Location: Berkshire.
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Posted: Thu Mar 23, 2017 10:25 am Post subject: |
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Perhaps that's the problem wrong coil or coil fitted the wrong way with the live to the negative terminal, it will still work but with a very poor spark. _________________ old tourer
Morris 8 two seater |
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alastairq
Joined: 14 Oct 2016 Posts: 1957 Location: East Yorkshire
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Posted: Thu Mar 23, 2017 10:53 am Post subject: |
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Is the fault the OP mentioned a sudden development? |
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Peter_L
Joined: 10 Apr 2008 Posts: 2680 Location: New Brunswick. Canada.
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Posted: Thu Mar 23, 2017 1:49 pm Post subject: |
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Hello James... Following on from Alan's previous comment, you may find this useful.
Quote: "So reversing vehicle electrical system polarity will reverse direction of spark drive. The engine still runs either way, but spark might be more reliable under marginal conditions if you get it right. The simple fix for this is to reverse the two primary wire connections on the ignition coil. Because the output spark is very much higher voltage (20,000v) than the car battery (12v), it doesn't care if the battery polarity is helping or hindering by a meager 12 to 14 volts in battery potential.
So how do we know which way to connect the ignition coil for best results? Original production coils were generally marked on the primary terminals "SW" for Switch and "CB" for Contact Breaker. This was assuming the vehicle wiring was connected for positive earth (positive battery cable grounded on the chassis). If you reverse battery polarity (going to negative earth), then these coils need to be connected with "CB" to the ignition switch and "SW" to the distributor points wire. Later issue ignition coils are marked "+" and "-" on the primary terminals. These are more no-brainers, as you only need to match the terminal markings to the battery posts. For positive ground the "+" terminal goes to the distributor (to be grounded on the engine block). For negative ground the "-" terminal goes to the distributor (to be grounded on the engine block). |
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