Suddenly no spark

[anaxemurderer]

Hello all

Got a new problem. Went to start rangie this morning for play day. Wouldn't fire? cranked for ages, bumped it jumped it... nothing. Definately getting fuel, checked a plug and no spark? It was running fine last night when i moved it and now nothing.

What would be likely culprits? obviously i haven't had time to check much yet?

Its a 3.5 on su carbs with original distributor etc.

thanks

Nick

[clbarclay]

You don't get a spark at a plug, how about at the dizzy?
Remove the HT lead and get some fool to hold it about 1/4" from a suitable earth and see if that sparks when engine is cranked. Don't crank the engine too long as if it does spark the fool my shout yes and then try to move the lead away from the earth, resulting in a mild discomfort :roll:

The official workshop manual has a good section in it for diganising the source of spark issues.

A friends 3.5 carb suffered a similar sudden lose of sparks which turned out tho be the ignition amplifier that had failed. Instead of like for like replacing the sepereate ignition amp, he remote mounted the later type of inginton amp that normaly fits to the dizzy at a fraction of the price.

[squaddie_fox]

agree with the above, its either the amp or the coil! easy to replace them.

[anaxemurderer]

Pardon my ignorance (still only learning this new fangled petrol technology!), but what is the ignition amplifier. I can't see anything that even closely resembles what ifound through google searchs or any mention of the item in my haynes book of lies!

Don't think its the coil, as i swapped that for a spare (which was ok when i took it off before, only had a crack in plastic terminal).

Anyhow i stil haven't had a chance to look into it, what with work and needing two people to check for spark/turn key.

Thanks for the advice though

Nick

[squaddie_fox]

the amplifier is a small black box almost a square, which will be located either on the distributor or on the wing near the coil. have you had the dizzy out? my mate did it and broke the counter balances on the dizzy.

is the rotor arm etc all ok?

[anaxemurderer]

Ah right, i thought that was called the ballast resistor? Its tiny, like 20mm by 10mm and attached to one of the coil terminals.

I haven't had the distributor out and still not done much investigating cause im still stuck on my own. Took stupid rubber cover of the cap today and swapped it for a spare (the terminals where full of corrosion). Going to do some to it in the dark this evening!

But yeah rotor arm and points look ok, might just buy new ones anyhow (cheap enough after all and it can't hurt).

Thanks

Nick

[Range Rover Blues]

Crieky, you've got points :-.

In that case you might well have a ballasted coil too.  Here's a thought, it's not rocket science to upgrade to an EFi dizzy which is electronic and gives a better spark.

Note to all, when removing the rotor arm you should try to hold the guts of the dizzy down with a screwdriver otherwise you can break the mechanical advance mechanisim by pulling the arm off the top of it.

[anaxemurderer]

Yeah sorry thought that might be what you were thinking, i assumed that when i said 3.5 on carbs you would think points not efi. Hence my confusion over the lack of ignition amp.

I have considered changing to efi dizzy or lumenition etc but can't really be bothered. Im running it on a very cheap budget. I believe i have sourced it to the condensor anyhow (which was one of my original thoughts), and as thats only £1.50 I think i can stratch that far (might even get a spare).

Interesting point about the rotor arm thing, didn't know that. Strikes me as a particularly bad design, especially as its an item that gets removed/changed fairly regularly.

Thanks for your help anyhow

Nick

ps I dare say electronic might be more reliable, would it cope better with water. (its definately an offroad truck so water is an issue!)

[Range Rover Blues]

Possibly it woould be more reliable, you certainly wouldn't get the point corrosion plus with a good set fof leads the stronger spark would be useful, might make a bit of difference to the economy too :-k

[forestrynick]

Ah ha... success! It lives

I decided i'd pretty much swap out everything, new points, rotor arm, cap and condensor. Coil is pretty much new anyhow and im pretty sure it was actually the condensor (though points weren't good). Wouldn't go straight away but at least had spark between leads and block, so cleaned up the plugs and away she went.

In fact it was a pretty productive afternoon, fitted new wheel bearings to drivers front hub and new trialing link bushes. Just have to repair a bump stop tomorrow and I'l take it for a spin.

Hurray for having a working truck

Thanks for help

Nick