Happy new year all .sj410 1986 intermittent misfire

[SteveR]

Hi all

as above,my sj has developed an intermittent misfire. within my ability I am checking all the obvious things I hope.
Symptoms, starts easy as before and runs well, at idle no probs and picks up revs no prob, in driving every so often just hear and feel slight misfire and power loss.
Points gap checked and timing ok ( with strobe gun ),starting with cheapest have ordered new points and condenser waiting for delivery.
HT leads, points and distributor cap and rotor arm all changed 3000 miles ago, plugs also same time.
Plugs nice colour brown all the same.
Inside distributor cap all seems clean and corrosion free, rotor arm clean and dry

So the coil !
The coil is original, I have put multimeter on it and get on between low tension connectors 1.5 ohms, reading between low tension and high tension connections 8500 omhs. Are these ok ?
Haynes manual only says low tension should be 3 ohms, is 1.5 ohms close enough ?. I have no idea on these electrical things.

Realise it could be plugs or new leads or anything but checking other things first.
Everything is clean no obvious cracks anywhere.
My sj is petrol and lpg powered and has same prob on both fuels so dont think it can be carb related as the lpg does not go through the jets. of carb only through the main body ( I have really no idea on these aisan carbs !

Any thoughts or ideas appreciated

Steve

[twiss]

It sounds like it could be the coil giving up but they are quite cheap to replace.
I agree its probably not the fuel if it does it in petrol and LPG.
Consider an MSD blaster coil, i got one and its very good, nice BIIIIIG spark

[ScottieJ]

An Msd blaster coil would fry the points Twiss

Could always swap to a 413/Sammy dizzy to solve that issue though.

Sounds like the coil isn't too healthy so I would swap that for a new one and see if that helps.

[twiss]

With ballast resistor of course... seem to run them OK

[SteveR]

Hi all

Just a little update.
I put new points on and all was well again. Old point s looked fine and had not done many miles , a bout 2000 miles only !

Until problems started when running on petrol, gpl was fine.
still to be investigated but I think carb jets must be dirty gummed up as I use no petrol .