Ransomes MK5 Fuel leak
Hello, I have recently bought a Ransomes Mk5. This mower is in okay working order but with a few small problems. I bought the lawn mower as I wanted a ‘classic cylinder lawn mower’ and wanted to ensure the machine is maintained. The previous owner was going to scrap it is it can be temperamental. I am an enthusiastic lawn mower novice with very limited engineering experience. Apologies upfront for the lack of technical knowledge. I was going to take this for a full service but didn’t know where to turn (I live nr. Towcester, Northamptonshire) and have now decided that I would like to increase my own understanding and try to solve the problem myself.
The major problem is that I see fuel leaking from the needle/screw at the bottom of the carburettor – I think this is called the drain assembly or drain filter (indicated by the red arrow below). Fuel also leaks from the choke screw or maybe called the choke shaft (indicated by the red arrow below). If I put petrol in the tank it will start to drip from the carburettor within a few minutes. Am I correct in thinking that too much fuel is passing through the valve into the cylinder?
Other problems can be that the engine cuts out when idling or struggles to start but I hope this is related to the fuel supply (above).
Any ideas on what the issue could be or how I can fix this greatly received?
Many thanks,
Mark
Forums
Definitely looks like the
Definitely looks like the dreaded two piece flo- jet. There's a lot of info available on line , some good and some not so good.
The fuel tap referred to above is the one below the fuel tank, not the tap like main jet adjuster shown in your image.
For now I'd just add to the above to take care when dismantling . Before removing the four screws holding the upper and lower parts together , remove the main jet adjuster shown in your image -unscrew the adjuster needle and then the hex " gland nut". That will reveal the slotted head of a long main jet or emulsion tube that runs at approximately 45 degrees up into the carb body. If you try to separate the two parts of the carb without removing that jet, damage will be done.
https://www.dropbox.com/s/k3cr1kas1lzul24/BS%202%20Piece%20Flow%20Jet%2…
https://www.youtube.com/watch?v=DqPXjtWO0KE
http://ppeten.com/forums/viewtopic.php?f=3&t=369
https://www.dropbox.com/s/x02pxjsi01rl04y/BS%20Flo%20jet%20repair0001.p…
There is nothing 'dreaded'
There is nothing 'dreaded' about that carb, if you treat it correctly. It sounds like you need to obtain a 'carb repair kit', to obtain this, you will need to find the model, type and serial numbers for the engine. These should be stamped into the airshroud (unless this has been replaced at some time), the numbers will start with something like '80302'.
You will also need a parallel screwdriver to remove the emulsion tube (the thing Wristpin warned about), the screwdriver needs to go inside the hole and fit the emulsion tube slot without touching the threads, use the wrong screwdriver and you will ruin the carb by reaming out the internal threads. If all else fails, B&S sell a suitable screwdriver.
By the way, what Ransomes do you actually have, 5M isn't a model name, it just means that it is the fifth variant of the particular mode and is fitted with metric bearings. If you are unsure, post a picture of the entire machine and we will tell you.
The reason why it is such a
The reason why it is such a pig to strip is that emulsion tube, I've stripped quite a few and almost every one had bad corrosion in the alloy threads below the tube so it won't unscrew, that is why the correct screwdriver is vital, the screwing a bit out, then back in, several times with lots of easing oil technique may get it out eventually and B&S sell a special tap for cleaning the threads up once you have removed it. The rebuild kit is also stupidly expensive, a brand new flo-jet carb for the 7hp engine (made in China) £15, a rebuild kit for the 3hp flo-jet, circa £40.
Many thanks for the reply.
Many thanks for the reply.
Merryman, Can I assume tha the full choke is turn the choke fully down to the right? Lastly should I only give it 1 pull with the full choke open? Please can I also ask what the special tap is for cleaning the threads?
Hortimech, the model is a Marquis Mk5. Picture below. I would like to make a full repair on the Carb rather than just turning the fuel supply on a off each time. Do you recommend that I purchase the repair kit or a new carb? I will post the serial numbers for the engine on Monday.
Yes, the choke lever is moved
Yes, the choke lever is moved downwards, clockwise, to give full choke. Incidentally, this is referred to as closed. Open is when there is no restriction, so you give it one pull with the choke lever down (closed). Then, if it doesn't fire up, open the choke half way, close the fuel tap, and try again. Your machine will have slight peculiarities of it's own, and you need to learn if it likes more or less choke in order to fire up. Once you know what works best, these engines are reliable, and less prone to getting dirt in a jet than many other small engines.
A thread tap is what manufacturers and mechanics use to make threads inside a hole, Those on the flo-jet carb are a special size so, if you need to "improve" the thread, you need this special one from B&S.
Honestly, I never take them apart unless I need to unblock a jet or, if they start dribbling while running, the risk of damage to that emulsion tube causes more problems than simply turning the fuel tap off when you stop the engine, which is good practice anyway.
That looks like the dreaded
That looks like the dreaded Briggs & Stratton flo-jet carburettor, and almost every one I have come across dribbles fuel when the engine is stopped. The reason seems to be that the float needle seems very prone to wear. You can get new needles, but I bet it won't be long before it is dribbling again. Another problem is you have picked one of the most difficult carburettors to strip that I have come across, and I have been working on engines for over 40 years. Most owners just turn the tap off when stopping the machine and only open it again just before starting the engine. Starting is another procedure that needs a "technique," full choke for the first pull, if it doesn't run, half choke and close the fuel tap or it will "wet the plug" and you won't get it to start until it dries again. Open the tap again once it does fire up of course.