Weak spark woes
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Thread: Weak spark woes

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    Muppet Widewhites's Avatar
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    Weak spark woes

    Been trying to sort this out for a week now and to be honest it is doing my nut!

    Got a Rover V8 with Lumenition electronic ignition fitted which last year after being stood for a while fired up without any bother. Ran smoothly up until the point where the coil overheated. Replaced the coil and it was fine again until that one did the same. Stupidly I had fitted the coil without a ballast resistor. Mate gave me a straight 12Volt coil and again started the engine but it was lumpy and would not rev without missing. So ordered up a Lumenition coil with matched ballast resistor and tried again. Would not even start this time as when I took a plug out and earthed it the resulting spark was orange and pretty weak looking!

    Next I scored another Lumenition power module off e-bay and last night fitted that hoping that it was the module that had gone down. Nope still the same, weak spark although the engine does now feel like it wants to fire up.

    So checked the voltages and have 12V where I should. Redid the engine earth lead, gapped the plugs, cleaned the rotor arm and cap, replaced the HT leads and still no joy!

    Now run out of ideas other than replacing the distributor but wanted to see if you guys could shed some light before going to the expense of changing it.

    Cheers

    Gary
    Turning good parts into scrap since 1984


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    Off the Xmas card list kapri's Avatar
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    Re: Weak spark woes

    Have you got a rev counter on it ? Does that flicker when cranking ,as it should? Try a seperate battery purely powering the coil ,if it goes you've a voltage drop elsewhere . Don't leave the coil ignition on for too long as they can fry some elctronic gubbins.

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    Muppet Widewhites's Avatar
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    Re: Weak spark woes

    Hi Kev

    No rev counter so cannot check that. Will try a seperate power supply though and see what that throws up.....if anything!
    Turning good parts into scrap since 1984


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    Re: Weak spark woes

    got the same problem on a mates pop at the moment , tried different coils dizzys, plugs bypassed wiring still refuses to start
    been doing some research and talked to rimmer bros and they reckon its more than likely the leads arn't up to the job ... seems there is a problem with rover v8s and ignition problems , also did you know that all the rotor arms are a few degrees out ? .. will watch and see if someone hopefully knows the fix ..
    Hot Rods Don't Leak Oil . They Mark Their Territory .

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    Re: Weak spark woes

    Hi Gary, might be worth banging in points and condenser just to eliminate the electronic side of things.
    I assume you have 12v when cranking the engine over? - checked the dizzy shaft for wear? checked the cap for cracks ? static timing ok ? TDC marks in the correct position?
    I have a dwell meter and timing light if you need them.
    You could always give Simon the Sandwich a call and borrow his dizzy.
    I'm stuck with my truck brakes at the mo but let me know how you get on.
    I read the news today - Oh Boy!

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    Muppet Widewhites's Avatar
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    Re: Weak spark woes

    Just spent a frustrating morning trying to get somewhere but failed miserably!

    Connected the coil and lumenition unit to a seperate battery and got a spark but still weak.

    Took the fan belt off and took all of the plugs out so the engine turned over really easily but still a weak spark.

    Redid the static timing yet again, no difference.

    Took the coil HT lead from the centre of the dizzy cap and when cranking over the spark from the lead can jump at least half an inch!

    Tried it again with a plug on the end of no1 cylinder HT lead earthed to the engine and again a very weak spark.

    It was at this point I called it a day as I am now out of ideas other than coughing up for a new distributor!

    Andy what is the problem with the brakes on the truck? Anything I can help with?
    Turning good parts into scrap since 1984


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    Off the Xmas card list kapri's Avatar
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    Re: Weak spark woes

    Try the plug straight in the coil king lead and compare the strength of spark with it in a cap lead. If it's stronger the problem must lie with rotor ,cap or leads. Don't forget to try it with a different lead in the cap as well to make sure it's not a single duff lead.

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