I recently picked up my first skiff, it has a 1996 50 hp 2 stroke mercury. when i start it the engine starts up and runs at idle for about 15-30 seconds then rattles off and dies, also its on muffs and not pissing through the pee hole at all. the pee hole seems to be clear i can blow air through it without feeling pressure. what would be the cause of theses problems?
If you're not mechanically inclined, my recommendation is to take it to an outboard service shop. If you are mechanically inclined, obtain the OEM shop manual and start at the lower unit, working up. A 15 year old outboard has too many parts to list, that just wear out due to use.
What Brett said. To me it sounds like some gummed up carbs or a bad fuel pump. And when your blowing air up the pee hole, dont blow too much (compressed air), cuz u can blow the hose right off the nipple of the water jacket cover, or wherever it be on a merc.. I would recommnd u get a complete service and inspection done first, then attack the running issue. I find that its easier to diagnose that way (on a motor of No known service history), so your not second guessing if a water pump is bad or a fouled out plug etc..
I am a bit mechanically inclined so i did some work on the outboard today. i took off the lower unit and took apart the water impeller cover to find the seals under and over the plate dry rotted. I ran some water tests with a hose and it seems the water was not being pulled up the intake because of the lack of seal in the water impeller case. New gaskets should fix that. I hooked up the hose to the water tube without the lower unit on and the water came out the pee hole fine with just water pressure. she started right up and kept running fine. Is it possible that the engine was turning itself off before because it wasnt being cooled?
NO the coast guard regulates all engine manufactures to idle speed only, if you are on the water and the engine shuts it’s self off due a safety mechanism to protect the engine you would be in harm’s way with no power so therefore the US Coast Guard won’t allow manufactures to shut the engine off completely, all warning systems will only slow the engine to idle at worst case.
If the seals are rotted, I wouldn't trust the impeller either. With the lower unit pulled, I'd replace the entire water pump assembly. Seals, housing and impeller...pretty sure it can be purchased as a kit.
