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Recently purchased Stihl fs36 strimmer from the dump for £10, the primer bulb woudlnt suck fuel and seeing as this is a common reason for small engined machinery to be thrown away I purchased a carburettor kit. I did this myself for the first time and after doing it, it worked. Not too healthy however, as it idled so high that the end span, it also was a bit lumpy when revved. After taking it apart to adjust the screws I have replaced the fuel lines which looked worn but unfortunately after this it doesnt want to start, simply coughs foul black liquid through the muffler even though there is spark and new plug. Any signs of life have been the occasional start with throttle open, it barely idles and soon dies. Please help, I've tried removing the spark arrestor and muffler itself and tried it then in case of a blockage, still just fuel out of the exhaust.

Sounds like it is flooding. Dump out all of the fuel and pull the rope until it starts, and burn off all of that excess fuel firstly. It should run great at the end as it burns the fuel out then stalls. The inlet needle in the carb is likely leaking, did it come in your kit?

Thanks for your reply, I will try this. Do you mean the needle valve? Apologies I am fairly new to this. I think the kit did come with a new needle but I didn't fit it I don't think mainly cleaned it and replaced the things I thought were passed it.

Fuel pouring out of the muffler is usually because the metering diaphragm is torn or the metering needle is stuck open.
For the novice it is best to replace the carb
As you paid £10 for a £ 150 trimmer it is probably worth while getting it looked at by a small engine workshop ( not a glass front retailer ) .

The metering diaphram was new so shows no defects, whilst the needle is clearly moving. Having taken it to small engine repair they seemed to have the same problem as me, the carburettor is no longer available, I have messaged a few up for spares but then carb has been sold. If you take the carb off and pour fuel in intake it runs. Is there nothing that can be done to save this strimmer before I list it up for spares or repairs.

Has anyone replaced the needle. The needle seat can be polished with a q-tip and an abrasive paste.

Most people only ever see one or two cube carbs together but when you do this every day it becomes blaitentely apparent that they are all the same .
They all mount on the same centers so can be changed with any other cube carb that has the same bore size.
All that is really different is what hangs off the end of the throttle & choke shaft.
However once again these are the same diameters so you can pull them out & swap them over from the bad body to the good body.
For me to do it is not cost effective but for a household handyman who is not charging out their time worth looking at for the fun of it .
So any carb for a 300 cc engine can be made to fit and should run it is just a matter of how much stuffing around you want to do.
When my old FS 43 finally died , I rebuilt it using parts from all sorts of trimmers.
The original fuel system was not pressurised ( only 1 line from the carb to the tank ) & it got replaced with a latter model that was pressuriesed so I had to cut a hole in the tank , fit a grommet & latter model fuel cap

I could try the needle, as to using a different carb this is a wierd and different one on this strimmer where the primer is near the fuel tank rather than on the carburettor itself. And if you substituted with one like that which seem very common the fs36 has a covered end so you wouldn't be able to prime it. Would you have any idea of what one might be suitable?

Remote purge carbs with a choke butterfly are used most regularly on chainsaws.
My parts book says it is a WT 160 which superceeded to a WT 492 then a WT 327
Almost any WT body can be used as a substitute as the choke & throttle shafts are the same diameter provided it has the same size bore
The WT 160 was used on engines from 15 cc through to 55 cc. So there will be a lot of carbs that can be made to fit.
To be honest I rarely bother doing this cause removing the butterflys are a PIA and then when you replace them you have to stake the end of the bolt to prevent it undoing & falling into the engine but I do regularly sell customer a couple of bodies for $ 5 and a rebuild kit for the same price.
To check if the bore is the same you check the part number of the actual butterflys.
When I do it, it is just a case of measuring the bores & I have boxes full of old carbs of dead tools
They will show a carb as "discontinued & Unavailable " if it has a 90 deg fuel spiggot but there is an identical one with a 45 deg spiggot or even a strait one

I have looked into some of these and have come across this:
This seems to be the same apart from the bronze pipes for the fuel lines to attach to (I don't know the technical terms) which seem to be the wrong angle, this may result in the fuel lines kinking and causing a blockage if attached. Are these Interchangeable or will this be ok? Another issue is that this strimmer relies on a plastic piece on the choke to be activated and deactivated from the outside, this carb does not have that but a small metal piece which may not reach outside the engine cover.

Well you fix the fuel lines by replacing them with longer ones to get a better run.
Chokes can be swapped over
If you have a choke on the air filter housing then remove the choke for the carburettor and plug the 2 holes the shaft goes through with some metal filler .
If the old carb has a butterfly choke then swap them over , it is just 1 screw & a circlip .

Here is a pic of the carb.

Thanks for your help, the carb is fitted and the strimmer works great. After meddling around with the different chokes, tuning and fuel leaking issues, the only problem I can't seem to fix is the fact that it won't idle, I've had a local workshop look at that and they reckoned they fixed it but it still dies, they did it for free so I don't mind. Do you have any solutions for this? I gather this is mostly the mixture screws problem but I'm not sure what to do with them.

I knew Stihl was one of the top suggested brands. My dad had a Stihl curved shaft trimmer which he brought for approximately $200 and now it has been working well for over 18 years. I just like to borrow similar STIHL equipment, and I am also impressed with how much better it works than the Ryobi that I'm using for almost 11 years. Normally, I trim weeds 2-4 times a year at most and the weeds I cut are commonly thicker. I want something BIFL, but it should be under $200 and with a lifetime of 30-40 years. Any suggestions are invited.

What your dad actually paid for the Stihl 20 years ago was 20 hours of his labour, not $ 200
SO to get an equivalent quality trimer today you will need to spend 20 hours of your labour at todays rate which will be a lot closer to $ 400