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Starting Problem


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Looking for some opinions.

On an inverted engine, On a good fully charged battery with the spark plug removed the engine turns over quickly and correctly. But as soon as I replace the spark plug it really struggles to turn over, with or without the spark plug lead connected?

Any thoughts?

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If the engine is not grossly flooding (fuel dribbling from the spark plug hole when cranking) then the issue must be with the starter / connections /battery.

Check connections to battery, starter switch or relay and starter motor. Both cable and earth connections need checking.

If you have an electrical meter you could make the following checks while cranking:

Voltage across starter motor

Voltage across starter relay or switch

Voltage across battery.

If there is full battery voltage right up to the starter, then the starter is suspect. Otherwise, the location of voltage drop should indicate where the trouble is.

Pete.

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If the engine is not grossly flooding (fuel dribbling from the spark plug hole when cranking) then the issue must be with the starter / connections /battery.

Check connections to battery, starter switch or relay and starter motor. Both cable and earth connections need checking.

If you have an electrical meter you could make the following checks while cranking:

Voltage across starter motor

Voltage across starter relay or switch

Voltage across battery.

If there is full battery voltage right up to the starter, then the starter is suspect. Otherwise, the location of voltage drop should indicate where the trouble is.

Pete.

Thanks Pete,

Kind of the areas I was going to look at as it is a brand new starter motor, so I suspect it must be further back.

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Barry my Simo was the same but the knack was starting correctly not saying your not but i would always from cold prime the carb, turn the prop by hand HT lead off and then replace lead and with no throttle at all turn over on starterit would 99 time out off 100 catch and run i would only attempt to open throttle after a couple of mins it would never start if i had any throttle at all and would always stall if i opened throttle before it was warm.

Dont know if this helps but i know starting Simo's as ive had a few and alway's had a results this way

Neilzy

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Voltage does not tell the full story of a battery.

If you battery is old, has not been fully charged/equalized monthly in storage, is low on water (assuming Lead/acid here and possible sulphation).

If you run Nicads, they may have formed internal dendrites limiting amperage output and storage capacity.

Nicads have a better chance of being recovered:

http://blog.makezine.com/2006/12/18/how ... d-batte-1/

Try a utility battery, or car battery in it's place to test other components with compression load.

May be your current battery just never had sufficient giddyup gumption .

Tick one vote for a lithium/iron replacement if you need to.

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Agree with above regarding battery - the heat and vibration isn't kind to the internal plates of the standard lead-acid battery, and the rectifiers fitted to many paramotors aren't the best quality. I shorted one battery when the rectifier failed, allowing AC to come through from the charging stator.

My Evo motor spins very fast on the starter and always fires within a second or two - but I've also got a fancy lithium-iron battery waiting to be fitted just in case (and it is 1.5kg's lighter).

Neil, I had similar starting problems with the Walbro WB37 carbs (not just on Simonini engines) and it was nearly always a symptom of mixture adjustment - either on the high & low screws, pop-off pressure or 'fluff' build up on the internal gauze filter. Also, Alex Varve's modification of the throttle butterfly plate works well (a small half moon filed off in line with the fuel intake holes).

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