I'll give you the summary of that link.
The Suzuki fuel pump has an integrated high pressure filter. This filter is needed to filter out the finest particles that could otherwise clog your injectors. Do NOT confuse this with the mesh "strainer" which is on the outside/bottom of the pump, and is only intended for course particles that could clog the pump.
Once the filter fills up, it restricts the flow of fuel and should be replaced. There is a fuel flow test that you can perform to see if this is the case. However, once you've confirmed it's the filter, there's not a lot you can do as the filter is integral to the pump. You can only replace the complete pump, which is costly.
Some clever people on VSRI have come up with the "external fuel filter mod". This consists of two parts. First, it requires you to drill a hole in a strategic location in the pump, which allows the fuel to bypass the clogged internal filter. So the pump can now pump freely, but the output of the pump is unfiltered. Second, you splice in an external (automotive) fuel filter in the fuel line from the pump to the injectors. This then replaces the function of the internal filter.
The drill-the-hole-in-the-pump bit is relatively easy. There are plenty pictures in the thread listed earlier to see where the hole goes. However, some people have problems viewing the pictures in the thread so a few days ago I copied them over to here: https://www.stromtrooper.com/dl650-d...ypass-mod.html
The splice-in-an-automotive-filter is a bit more involved. The original fuel line is plastic and can't be cut to insert a fuel filter. So instead you need to buy a length of new FI-grade fuel hose, splice the filter in line (use proper FI-grade clamps), attach two connectors and use that assembly to replace the existing line. Sounds like a lot of work, but you'll likely find that taking the plastic and the tank off and putting it back on is the majority of the work.
In the thread listed above the suggestion is to carefully snip the original fuel line off the connectors so that you can re-use the connectors and O-rings. However, in a later post (reply #311) somebody found that a particular Dorman connector (#800-081) works just fine. However, I don't know if you can obtain those in ZA within a reasonable timeframe, so you might have to reuse the existing connectors. The rest of the components (a length of FI grade fuel line, an in-line filter and four FI grade hose clamps) should be obtainable virtually anywhere from any auto parts store.