I have a 1991 Mariner 2 stroke 20hp outboard with a pull start. I’ve had it since last Christmas and haven’t had any trouble getting it to start or run until now. A few weeks ago I launched at Virginia ave and rode all the way to Beresford creek on Daniel Island with no problem. Shut the motor off to fish and fired it back up to move up and down the creek numerous times with no problem. In the middle of shutting it off and on to fish, we got rained on for 10 mins. When it came time to head back home the motor would not start. I probably tried hand cranking it a 100 times. Luckily enough a home owner let me use his dock and landing to get my boat on the trailer in Daniel Island.
A week or so goes by and I try to pull start it in the garage and it fired up. I didn’t let it run long at all since I didn’t have earmuffs hooked up to it. When I get it in the water at a boat landing it will not crank. So, I brought it home and hooked up the earmuffs and it ran fine, so I take it back to the landing and with the back pressure from being in the water it will not start.
I get it home and check both spark plugs. The sparks look good. Next I performed a compression test. Both are 110psi. So since the spark plugs and compression looked good, I replaced the fuel filter and pull off the carburetor to clean it. It already looks clean as I take it apart, but I clean it anyways since I’ve already disassembled it. After reinstalling the carb I put the outboard in a test tank and it still will not start. After many failed attempts at getting it to start with low speed mixture screw where it used to be, I followed the owners manual for carb adjustments and I still can’t get it to start. The only thing left to do, that I could think of, is to try different gasoline. The boat is always kept in the garage, but it did get rained on the trip that it stopped working. So maybe water got in the gas. I get a fresh gallon of non ethanol gas and mix it 50:1 with the marriner/merc suggested 2 stroke oil. It still wi
If you are 100% sure that good fuel has made it through the whole fuel line and filled the carb bowl, I’d probably look at the fuel pump next. It should be fairly simple and cheap to rebuild it.
Try some Seafoam in a spray can to the carbs! Mix it with your gas. Is the motor pull start or el. start? I have a 25 hp merc 1992 with ? hrs and it run like a scalded dog. only problem I have ever had is bad gas!!
Check the exhaust opening on the back of the engine,too, just to be sure you don’t have a blockage there (mud daubers). I had that happen to my 15 hp mariner once, causing excessive back pressure when the lower unit was submerged.
Try some Seafoam in a spray can to the carbs! Mix it with your gas. Is the motor pull start or el. start? I have a 25 hp merc 1992 with ? hrs and it run like a scalded dog. only problem I have ever had is bad gas!!
I’ve tried fresh gas, starter fluid in the carb and directly into the cylinders and nothing has helped.
Weak firing , borrow a tester or open up the gap on a plug to at least 1/4" . You should get a strong blue arc . I used to hold the plug wire and grounding that same hand to the motor while you turn the motor over slow or in short bursts . If it didn’t knock the pee out of me it was weak . I have tested them that way a bunch of times and if it’s good I would know . Stop using that either you might ruin the motor . Don’t do the above if you have a weak heart in fact don’t do it at all , just get a tester.
Weak firing , borrow a tester or open up the gap on a plug to at least 1/4" . You should get a strong blue arc . I used to hold the plug wire and grounding that same hand to the motor while you turn the motor over slow or in short bursts . If it didn’t knock the pee out of me it was weak . I have tested them that way a bunch of times and if it’s good I would know . Stop using that either you might ruin the motor . Don’t do the above if you have a weak heart in fact don’t do it at all , just get a tester.
Make sure you use either with upper cylinder lube and in short bursts he’ll be fine. Quick way to see if it’s a fuel issue. Only engines I’ve seen ruined by either were diesels. I’m sure it could happen in a gas engine, but I’ve never seen it in a lot of years using it and seeing it used.
Some mentioned timing, did the engine “pop” back/ back fire any when you first had your problem? Have seen flywheel keys sheared off from a back fire. You’ll get it!! only so many things it can be and you seem to have eliminated most.
What easy said about trying to start it in the dark, could have cracked plug wires arching and killing spark. They usually show up pretty good in the dark.
Fishingpox, you are a better man than me. It would take a lot of money for me to hold a spark plug wire on purpose!! Had mom hold the push mower plug wire once. Dad didn’t think it was a joke. Got several chops from the belt for that one!
“If Bruce Jenner can keep his wiener and be called a woman, I can keep my firearms and be considered disarmed.”
Just FYI regarding your new fuel that you added, you need to disconnect the fuel line at the carb and continue to prime it for about 30 pumps to ensure that you have purged the fuel line, filter, and fuel pump free of any diluted, stale, or bad gas. There will definitely be more fuel in the fuel pump that was hidden and will be the first to enter the carb. Make sure to drain the bowl and even spray with non chlorinated brake cleaner before reassembly of the bowl and fuel line. Also if the motor has coils clean “ALL” grounding wires at each coil and grounding wire at power pack as well as the point on the block that this connector will be making direct contact with a wire brush or sandpapper. Bad grounds will not allow these valuable components to function properly.
“If you can’t fix a woman, chase some tail with fins and fur!!!”
2008 Sea Pro 1900cc w/115
(2) Daughters that make the boys cry
(1) wife that makes her husband take the kids outdoors to chase their dreams!
