• Mercury 115 Outboard Troubleshooting Guide

Rules within the EU mean you can no longer buy a new, small 2-stroke outboard motor in Europe, but their light weight, compact size and longevity means tens of thousands of used examples are still to be found on boats from Caithness to Crete. The start of the season is when any unreliability issues are most likely to rear their ugly head, and there’s a good reason for that. ‘Most people assume they can just take their outboard off their boat and put it straight into their shed for the winter,’ technician Steve Dawkins told me in his workshop at the Cabin Boatyard on the Hamble River. ‘Then, come the spring, they’re surprised when it doesn’t work.’ I kept quiet. My outboard had been sitting forlornly in the garage among a pile of ropes, fenders and sails since it came ashore at the end of last summer. Do it yourself!

This step-by-step guide takes you through a service of a small 2-stroke outboard. The pictures show Mariner 3.3hp and Suzuki 2hp outboards, and while other makes of engine are subtly different, the main components should be recognisable. Anyone with a reasonable level of technical ability should be able to breeze through the service, but if you’re in any doubt, take yours along to a dealer.

If you are going to do it yourself – and this mostly applies to late-model motors – check first that what you’re doing won’t invalidate any warranties. 1: Drain the old fuel ‘The most common complaint we get is from people saying it worked fine last year but now it won’t start,’ said Steve. This is because petrol evaporates over time, leaving behind an oily, paraffin-type residue which gums up the carburettor. So the first step is to drain the old fuel.

Mercury 115 Outboard Troubleshooting Guide

8: Now reattach the gearbox to the lower leg. Carefully slide in the gearbox, making sure the water pickup pipe (small spigot just above the gearbox linkage in this photo) is unblocked and lined up correctly inside its socket. On smaller engines with only one gear Remove the propeller and then the plate behind it. The water pump impeller can be found behind this plate. Check and replace the gearbox oil The professionals perform a pressure test to check the seals are still doing their job. Without the right equipment you’ll struggle to do this, so you’ll have to make do with a visual inspection. One way to see if you have a major problem is to leave the engine standing on a piece of clean cardboard overnight and check for telltale leaks in the morning.