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Old 14-10-2015, 14:57   #1
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15 hp Mercury 2 stroke won't run

Been a great dingy engine until now. Sat up for 2 to 3 months, outside in the weather. Tried to start and it started, but had to choke it to keep it running. Started and choked it several times, it will run for a short time and then dies like it is starving for fuel.

Put in fuel from reserve tank that has been sitting around for about 3 months. Finally replaced spark plugs and it started but only ran for a couple minutes, then had to choke it to get it started again.

Any ideas as to the culprit would be appreciated. Just spent $350 with dealer before this lay up period for new fuel line and a few parts. Would this be caused by too much oil in the gas mixture?
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Old 14-10-2015, 14:59   #2
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Re: 15 hp Mercury 2 stroke won't run

Most likely clogged jets in the carb, strong indicators are it won't run without the choke and it sounds like it is running out of gas.


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Old 14-10-2015, 16:36   #3
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Re: 15 hp Mercury 2 stroke won't run

a64pilot is right. I have a similar Merc outboard and it clogs during layup if I don't add fuel stabilizer. It usually blows out with pressurized can of carb cleaner.
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Old 14-10-2015, 16:51   #4
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Re: 15 hp Mercury 2 stroke won't run

Mine was like that when I first bought my boat. A full cleaning and rebuild of the carb was the cure. Also replaced the fuel pump diaphragm because it would run at idle, but at high speed it would start to die. Also use the blue stabil to counteract the ethanol problem. I haven't had a problem in 5 yrs. Starts with only 1 or 2 pulls.
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Old 14-10-2015, 17:20   #5
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Re: 15 hp Mercury 2 stroke won't run

Like the other said fuel should be changed but I would also suspect the fuel pump diaphragm. Choking it will increase the vacuum which may cause a faulty diaphragm to work.


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Old 14-10-2015, 17:34   #6
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Re: 15 hp Mercury 2 stroke won't run

A way usually to confirm a faulty fuel pump is to pump the bulb, if it runs fine as long as the bulb is kept tight, that is a good indication of a faulty pump


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Old 15-10-2015, 06:31   #7
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Re: 15 hp Mercury 2 stroke won't run

We have this engine (2005) and it starts better than any 2-stroke ever owned. It did sit on the stern rail for 5 mos once without stabil. To get it to start, put a rag down the carb inlet and pulled a few times, which cleared up the no fuel problem, and ran good since.

Tip by A64 pilot on fuel pump and primer bulb is good too, in case that keeps it running.
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Old 15-10-2015, 06:39   #8
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Re: 15 hp Mercury 2 stroke won't run

I had to get home with my Mercury Verado big supercharged outboard by using the primer bulb once.
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Old 15-10-2015, 09:02   #9
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Re: 15 hp Mercury 2 stroke won't run

One should only use premium (non-ethanol) gas in outboards
Bill

Also use the blue stabil to counteract the ethanol problem. I haven't had a problem in 5 yrs. Starts with only 1 or 2 pulls.[/QUOTE]
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Old 15-10-2015, 09:12   #10
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Re: 15 hp Mercury 2 stroke won't run

Had the same problem. Repairman told me to only use non-ethanol fuel and always shut the fuel off and run the engine until it dies. That way the carb bowl is empty.
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Old 15-10-2015, 09:59   #11
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Re: 15 hp Mercury 2 stroke won't run

Quote:
Originally Posted by a64pilot View Post
Most likely clogged jets in the carb, strong indicators are it won't run without the choke and it sounds like it is running out of gas.


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Old 15-10-2015, 10:36   #12
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Re: 15 hp Mercury 2 stroke won't run

Quote:
Originally Posted by anacapaisland42 View Post
One should only use premium (non-ethanol) gas in outboards
Bill

Also use the blue stabil to counteract the ethanol problem. I haven't had a problem in 5 yrs. Starts with only 1 or 2 pulls.
[/QUOTE]

YES! YES! YES! YES! YES!

If you can get ethanol Free, get it. Search the internet for ethanol free. Also its illegal to use ethanol in aviation gas motors, so you can get it at all airports though you need to sign a waiver that you will use it only on your small plane.

1. http://www.theoutboardwizard.com/out...anol_fuel.html

2. http://www.alloutdoor.com/2013/06/25...tboard-motors/

Use double the dosage of blue Stabil. And run the carb out when you quit: pull the gas line and let the engine run until it stalls.

Ethanol in gas should be illegal. Outboards won't run with it easily, and newer 4 cycles are the worst.
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Old 15-10-2015, 11:01   #13
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Re: 15 hp Mercury 2 stroke won't run

I have a 3 HP Merc 2 stroke for my old dinghy. Starting running rough, hard to start and finally wouldn't start at all, not even a sputter. Was just positive it was a carb/fuel problem as I was in an area with no access to ethanol free gas.

Pulled the plug to see if there was gas in the cylinder and I didn't notice a spark when pulled the start rope. Put in a new plug and it was like new.

I would have bet money on the carb but the plug fixed it. For $3-4 I would at least give that a try.
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Old 15-10-2015, 11:24   #14
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Re: 15 hp Mercury 2 stroke won't run

I have this motor and have found that the float bowl was emptying and then wouldn't refill. Cleaned the carb and all good to go. I've found that in a pinch I pull the carb and shake it until I hear the float rattle, put it back on and off I go until I can take it apart.
Eco gas is the culprit. If using ethanol laced gas that is more than 30 days old you will continually have this issue.
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Old 15-10-2015, 11:45   #15
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Re: 15 hp Mercury 2 stroke won't run

I have one. Water in the gas does it. Then carb needs to be removed and cleaned.
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