If you want to get real technical, you may wish to specify what make and size outboard motor is aboard the Grampian. I'm suggesting this because some motors have chokes, while others have primers. While they perform a similar function, the WAY they perform them is different. A late '80's vintage 8hp Johnson Sailmaster would be a typical engine on a Grampian, and they don't have chokes, they have a primer. Once the primer bulb on the fuel line has been pressed until firm (meaning gas has reached from the tank to the outboard), your hero would then need to pull the black priming knob on the engine. This squirts a small amount of fuel directly into the carburetor prior to pulling the starting cable. A choke, found on other engines (Mercury and others), doesn't do that; it closes a butterfly valve which enriches the mixture (larger proportion of gas to air) to aid starting. Once an engine is warmed up a bit, the choke is turned off so that the mixture can return to the proper ratio for warm running.
I like ReefMagnet's suggestion of removing the spark plug; they get fouled sometimes especially on two-stroke engines, and pulling a plug and cleaning and gapping the electrode or replacing the plug with the spare that you SHOULD always have with you (have the hero curse himself for not having one, or the heroine rag on him for it..) is a not-at-all uncommon thing to do if you can't get a motor started.
NOW.. here's a few other things that can go wrong. On a Johnson, there's a very small fuel tube coming from the primer knob assembly that fits onto a small nipple on the carb. That line can come off if not installed properly, and the priming gas would then just squirt into the engine compartment of the outboard where it does no good other than create a small fire hazard (not likely, but maybe your hero/heroine smokes? <evil grin>). Plus, since the line isn't connected to the carb, it creates an air leak in the carb so, even if the engine DOES eventually start (it's possible), it'll run like crap. Go ahead... ask me how I know!
In addition to the aforementioned broken pull cord, there's also a safety interlock on many motors which prohibit the pull cord from being pulled if the throttle is advanced too far or the engine is in gear prior to pulling the cord. Perhaps the hero had advanced the throttle too far trying to get more gas to the engine and, in a panic, just horsed on the line with all his might forgetting about the safety interlock, which caused an aging pull cord to finally snap. OR.. maybe the interlock jammed, and he had to remove the engine cover housing and break off the interlock tab with a large screwdriver or chisel and a hammer. Maybe an injury in process? <another evil grin>
For an engine to start, you need fuel, spark, air, and "coordination"... the spark has to hit the air/fuel mixture at the right time, i.e., at a certain travel point of the piston which results in compression of the fuel/air mixture. Soo, if the engine isn't starting, it's either fuel-related (primer bulb, primer/choke, fuel lines, gummed up carb, bad gas, wrong mixture ... possible dialog .. "Fifty to one gas to oil?!?! I thought you said mix it fifTEEN to one!!!"), air (tough to go wrong here in an outboard, but maybe bees made a nest in the air cleaner cause the engine had sat unprotected and unused for a long time? Totally clogged filter? Too much air due to bad carb gasket or aforementioned tiny primer fuel line disconnect?), spark (fouled or otherwise bad plug, bad plug wire, bad magneto), or bad timing (usually a set and forget on outboards, but anything's possible). Then there's the mechanical issues.. safety interlock, throttle cable, starter cable.
Does his Grampian have remote engine controls, i.e., a single or dual lever throttle and gear shift further ahead in the cockpit? If so, it's possible that one of THOSE cables could seize, which would mean he'd have to go back to the engine and disconnect the remote cable to regain control over the related function (throttle or shifter). The shifter wouldn't be a problem, but the internal throttle cable is usually disconnected if a remote throttle control is used. This would necessitate reconnecting the internal cable so that the throttle twist control on the outboard's tiller would work, or just operating the throttle mechanism directly by hand with the engine cover off. This could be dangerous, too... could get some article of clothing caught in the spinning flywheel once the engine's running.
Man, after thinking about this, it's a miracle we DON'T have more engine trouble or catastrophes... <grin>.. this is fun!
Let us know how things go. I'm a voracious reader, and would be happy to read and/or proof any excerpts if that would be helpful. Feel free to pm me.