Suzuki DF4 ignition spark problems

trevbouy · 29 June 2021, 18:00

Hi all,

Numerous issues with engine but it did run. Need new thoughts on it.

I had a stuck broken bolt in the thermostat housing which led to casting damage. I had the casting AC Tig welded and re-tapped.

The engine then wouldn't start and checking for a spark found it was missing.
I assumed by not removing the ignitor/ignition during welding the AC current had fried the device.

As a new unit is over £180 I elected for a used part from the USA from a known dealer. Once it arrived I fitted it only to discover still no spark.

Today I bought another used part from a local outboard dismantler who claims it came from a running engine. Guess what still no spark.

Tried -

removed the kill switch wires from uinit (it shorts to stop)
Removed spark plug and held HT lead close to block, nothing.

Given that the unit just works by a rotating magnet on flywheel crossing coil to enegise it I'm stuck now.

Fenlander · 29 June 2021, 18:19

No expert on this but I'd assume there was the potential for damage to every part of the ign system and its wiring during welding. You'll have to go through it all with a tester to check for shorts and/or open circuits I reckon.

jeffstevens763@g · 29 June 2021, 19:36

I’d agree with fenlander but you don’t mention new spark plug very common for failure

trevbouy · 30 June 2021, 08:32

Thanks for suggestions guys.

New spark plug but a test of HT lead end close to earth still produces no spark. Final test, hold a scredriver in end of lead and see if I get a shock. No unfortunately.

It's a simple system really. There is a large magnet on the flywheel which crosses past two multi laminate arms of a U shape ignitor exciter bolted to housing. In the potted housing is an electronic amplifier cdi ignition which converts it to a spark. There are no wires except one which is grounded by the killswitch to stop spark. It's no connected for tests.

If there is something else preventing it working I don't know what it is?

Fenlander · 30 June 2021, 09:33

Ahh yes just looked at some images and diagrams... it is self contained and once the stop wire is off no other external wiring to have been damaged. Have you tested the two used coils... long shot but what if both faulty.

I once needed a new airbag ECU and the first two despite being claimed as fully tested working were both U/S and only a further third one purchased later actually worked.

Also... and this is way outside my experience/understanding... could the welding pulses have de-magnetized the flywheel magnets?

Oldman2 · 30 June 2021, 10:50

Quote:

Originally Posted by Fenlander

Also... and this is way outside my experience/understanding... could the welding pulses have de-magnetized the flywheel magnets?

I have an old Seagull 40+ outboard, these after years on the shelf loose flywheel coil magnetic attraction causing no spark. The way to revive them is to take out the plugs, remove any fuel intake & lube the bore to ease friction and connect a drill to the flywheel nut and run it for 4-5mins.
A long shot but it costs nothing and it works for seagulls.

You will need the engine in a bucket of water or the impeller will be dry running for 5 mins.

trevbouy · 30 June 2021, 17:44

That's interesting. How does it re-magnetise? Is it magnetising the steel laminate pack on the ignitor? Worth a try at least as it is sat in a tub of water at the moment.

The magnet on the flywheel is quite strong and will hold a spanner easily.

trevbouy · 30 June 2021, 18:28

Ah just looked up threads on this subject, it's for magnetos.

The system in the DF4 isn't the same, there is a single strong magnet on the flywheel which just makes and breaks the circuit. Electronics in the coil pack convert it to a spark.