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Collection, Preservation and Display of Old Lawn Mowers

Marquis/F12 - basic problems

Back (good grief) 1998, I relaid my lawn, and  I also bought a s/h cylinder mower from my local auction. I had this repaired by the local mower shop, including a new/old stock Amal 379 carburetor.

Sadly, using the mower eventually gave me horrifically painful tennis elbow, which took the best part of 3 years to go away, so I put the mower away.

A couple of years ago, I tried starting the mower; it started fine, but would only run for 30-40 second before fizzling out, and wouldn't restart. Leaving it for a day would allow this to be repeated. These (google!) sound like classic gummed carburetor issues.

Having found this helpful forum, and signed up (last week) I though I'd confirm the symptoms, so yesterday I put half a pint of petrol into the (empty) tank.

On opening the fuel valve, petrol starting coming out of the valve onto the engine body, although I was able to start the mower before the leak emptied the tank. Start-run-fizzle, as before.

So, I think I have two problems needing cures; a dried out fuel valve, and a gummed carburetor.



My facilities are at the shed level - workmate, small bench vise, spanners, socket set, wire brushes.

My goal is a working grass cutting device, not a concours d'elegance entrant!


18" Ransomes Marquis

Engine stamped "F12-02-02 60142"

Amal 379 carburetor

Ewarts fuel valve.

Any and all advice/links welcomed.



bugbear Mon, 03/06/2013

OK. At the risk of revealing the true depth of my ignorance:

It looks like I need to remove the fuel tank to get at the fuel valve. I tried undoing the two visible nut and bolts on the right (view from the front) but it felt like there was still some kind of rubber mount in middle of the tank.

* how do I remove the fuel tank?

* how do I disassemble the fuel valve to replace the plunger?

"A carb strip and clean should solve any problems in that area,"

I would more-than-welcome detailed advice on this - I'm guessing some helpful person has posted a sequence in the past.

I'm sure this stuff is meat 'n' drink to you guys, but I need help.


hortimech Mon, 03/06/2013

If I remember correctly (and please bear in mind, it has been sometime since I last did this) you need to remove the airshroud (big green thing with starter bolted to it) to get to the remaining tank bolts.

Remove the sparkplug, remove the two bolts next to the sparkplug, remove the two small bolts at the bottom of the airshroud. Now pull the airshroud slightly, then unclip the fuel pipe, disconnect the stop switch (if fitted), now totally remove the airshroud  and you should now be able to see the remaining tank bolts.

Just a word of caution, take care when retightening the two head bolts (the ones next to the sparkplug), they have a nasty habit of stripping in the block if you overtighten them.


wristpin Mon, 03/06/2013

No need to remove the tank nor the shroud - just change the tap plunger. Back off/ or remove  the small screw under the tap enough to clear the plunger, pull out the old plunger and replace with a new one and then relace/retighten the screw. Good idea to lubricate the plunger to ease insertion and reduce risk of damaging the cork seal . 

bugbear Tue, 04/06/2013

Excellent - I think even I can manage that!


Undid screw, removed tap (cork has compressed right down to the diameter of the brass) dumped it in a jam jar of petrol (am I an offical engineer now? :-)

If anyone has a "worth a try" approach to de-gunging a carburetor that doesn't involve anything as intimidating as a  "simple strip down" I'm all ears.

Failing which, a link to a nice illustrated "how to strip, clean, reassemble and tune" a carburetor would be most helpful.


hillsider Mon, 03/06/2013

Before buying a new tap plunger you could remove the old plunger to inspect it, if it is in good condition but the cork has dried out tie it to a piece of string and suspend it in your petrol can for a couple of days this will swell the cork and then it will seal ok when refitted to the tap. As has been suggested the carb would benefit from a thorough clean if only to eliminate any doubt that there may be dirt lurking in there.

wristpin Tue, 04/06/2013

The Amal carb on a Sloper is about as simple as they get. If it's gunged up and you don't have access to an ultrasonic cleaning tank, stripping  and cleaning is the only way to go. Even with a tank it is normal to strip the carb to give the ultrasonic process the best chance of getting into all the nooks and crannies.

If you've mastered email and posting images on this site an Amal carb strip should not be too daunting!

bugbear Wed, 05/06/2013

Can anyone recommend a "how to strip, clean, ressemble and tune a carb" tutorial, either on here, the web, youtube, or in a manual?


bugbear Thu, 20/06/2013

Undid screw, removed tap (cork has compressed right down to the diameter of the brass) dumped it in a jam jar of petrol

For the benefit of other reading (or googling) this thread, I can confirm that the cork has now swelled nicely, and looks like it may well once again turn fuel on and off.

Thanks for the advice!



bugbear Sat, 29/06/2013

Even better news. Having run the engine until it fizzled on a couple of occasions...


... on the third it kept going, so I cut my entire (1/4 acre) lawn with it.


It appears that the nice fresh petrol has cleaned the carburetor, at least well enough to run.

Go  go Villiers F12!


hillsider Sat, 29/06/2013

Good to hear that you have been successful geting your mower to run, if you explore the technical help section of this site and open Mower settings you will find a section entitled Engine manuals open the file and you should see a handbook for the Villiers F12 engine, this has only recently been added to the site and you may find it helpfull . Ray.

bugbear Thu, 08/08/2019

Well "darn".

I eventually got my lawn mower repair guy to fit a new fuel tap.

Then (following a summer which KILLED most of my lawn) I didn't use the Ransomes at all.

I went to use it last week, and the ... (new) fuel tap cork has completely dried out.

Is there a corkless (brass taper?) kind of fuel tap I could upgrade to?


wristpin Thu, 08/08/2019

This is worth a try.

Put the plunger in your coffee mug, pour some boiling water over it and leave it to soak. It may swell back to size and the coffee will probably taste a bit off for a while but it could work.

bugbear Thu, 08/08/2019

Thank you. The one on the left is very much what I was hoping for.