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Ignition problem on a 3.9


muddywaters
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3.9 V8 Rangerover engine failed to start whilst away from base - no spark - recovery man decided it was the ignition module (on the dizzy) and resolved problem by tapping it with a hammer while I spun the engine. I offered to buy the hammer ;) but discovered that my own worked just as well and used this highly scientific method successfully for several weeks while waiting for an opportunity to try changing the module.

In the end the hammer stopped working and I changed the module - surprise surprise - no difference - except when I spun the dizzy out of the engine and had a good spark. ( I clip an old HT lead with an earthed plug to the coil HT to check this) Taking the dizzy out and then putting it back in (something I've scraped my knucles doing several times) seems to effect a temporary 'repair' but it doesn't last and the hammer still isn't working!

Eventually I replaced the two leads from the dizzy module to the coil (leaving the old +ve feed still connected at the coil). Success - I started it twice a day for a week, even though I wasn't using it, until, on the day I needed the Rangie, it started in the morning but didn't start at lunchtime (should of expected this) when I was about to go out.

There was power at the coil and back at the module but no spark (although on several occasions there was a single spark when the ignition key first spins the engine over even though there is still power to the coil all the time the engine is spinning)

Has anyone else experienced this/have any suggestions apart from dumping it?

Cheers

Muddywaters

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You appear to have ruled out a faulty module. Are there any breaks in the wiring & the moving about temporarily closes the break?

Are the rotor arm and dizzy cap Genuine parts (aftermarket ones on the V8 simply will not do and are the cause of many difficult to trace faults including earthing through the rotor) and in good condition?

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I wonder if the dizzy internals are worn, and endfloat/play on the shaft is allowing the trigger wheel to move out of alignment with the pick up? The gap is notoriously picky! Or could be the gap adjustment is too wide, and some play in the mechanism takes it out so far it doesn't work? Setting the gap is not difficult but you must use brass os ally feller guages, steel ones have a magnetic signature which whill knack the pick up.

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