Fergie tractor running/starting faults. Fixed!

[spartacus]

So, Mrs Spart and I have a 1951 Fergie tractor. It's petrol, although it can run on TVO. It's 6v, so turns over at steady pace on the starter but usually fires up from cold first time.

It'll run great for 15 mins or so, then gradually drop on to 3 cylinders, at least that's what it feels like, if I try and let it idle for any reason, it'll cut out. Re starting on the 6v battery is impossible but it'll fire up eventually on a12v with the jump leads. Once it's cooled down a little it'll run on 4 like it should.

I've got my own thoughts on a couple of things that may be the cause but I'm not going to voice them yet as I want unbiased thoughts on what might be the cause.

Thanks in advance team!

[Dick Cheeseburger]

Can't help, but I do demand photos. T20? 

[Asimo]

Plugs, coil and condenser are all culprits for those symptoms. 

Does the misfire get worse under load?

[Zelandeth]

Coil breaking down when warm would probably be my first guess, secondly would be a weak spark due to a badly worn/faulty distributor cap or rotor arm.

A lean mixture requires a stronger spark than a rich one to ignite.

Assuming this has any of those things...we dealing with a coil & distributor setup here or does it have a magneto instead?

[spartacus]

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[spartacus]

Here you go. Not restored or anything like that, just a solid workhorse.

[spartacus]

It has coil, dizzy and condenser.

I think my suspicions are confirmed. As well as an ignition service kit I'll pick up a new coil too.

[spartacus]

Asimo, it doesn't appear to get worse under load just when it gets warm.

[Dick Cheeseburger]

19 minutes ago, spartacus said:

Here you go. Not restored or anything like that, just a solid workhorse.

Bloody love that. If I had a large driveway etc...

[junkyarddog]

It could be a plug lead breaking down too,

I had this recently on one of my Vivas,took a while to figure that out,against carb fiddling and condenser/points changing.

Lovely little Fergie!

[Dan the van]

I'd say coil as well.Have a real soft spot for petrol Fergies,first vehicle I ever drove at age 10.Looks great.

[spartacus]

Thanks for the love!

We bought it about a year ago for smallholding duties, the main issue with it is the coupling doesn't work, that's a job for another day though.

It's a relaxing old thing to drive and is road registered, it's seen as normal round here to use a tractor to go to the shops, so that's sometimes what I do.

[spartacus]

Quick update on this, I ordered a new coil, it turned up but was wrong. I sent that back and ordered another one, with more success! I fitted it one evening last week and the little Fergie fired up straight away. Cold starting was never the issue though, I would never dare switch it off and then try and start it warm. After chain harrowing one of the paddocks last week and doing another today, both times switching the tractor off to connect up, open gates etc I can fairly confidently say the issue is fixed, hurrah!

Thanks for all the opinions and advice.