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Discussion Starter #1
So I had a beautifully running 2005 Johnson 15 hp this summer that started up easily (2 pull usually). It sat for about 2 months without use, but with gas in it (ethanol free).

I've been able to get it started twice in the past three weeks, but can't get any consistency out of it. It's a pull start.

July - Carb rebuilt, motor completely tuned.
Plugs changed - last week (for the third time since spring)
Flushed out the old gas before changing plugs.
New gas, different tank two weeks ago.
Last weekend I ran it for ~ 15 min, then disconnected the fuel line to let it run out.

The motor sounds very close to starting, as opposed to having dead plugs, but it "coughs" instead of firing. Any suggestions would be great, and as always, thanks in advance for your time and knowledge!
 

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If you spray or shoot a little fuel mix into the carb does it do the same or does it "run" till the bit of fuel you added runs out?  If it runs then you probably have a fuel delivery issue.  If it still coughs and sputters then it is either an ignition or compression issue.  Given what you said I doubt it is a compression problem but I'd check anyway.  BTW if it is very temperamental to the amount of fuel in the carb it can be very tough to spritz fuel in and have it run, that's never happened to me but I've heard from others it can.

Did you use stabilizer in your fuel?  Two months is enough to cause problems and the chances go way up if you don't use stabilizer.  My gut says it is probably fuel delivery but I've had it happen that the pulse wires from my ignition module had the insulation wear through right as I shut my motor off and then let it sit for an extended time (about nine months).  The point is that it can be coincidental that you let it sit for 2 months, it may have done the same thing the next day.  Check everything after you rule out that the fuel system is definitely not the problem.

I hope you just need to pull and clean the carb (again).

Swamp
 

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Discussion Starter #3
Okay, so I've tried playing with different things to try and narrow down the issue.

After checking, Fuel delivery is not the issue and it wouldn't fire with starting fluid. I don't have a way to check compression, so I don't know about that.

I waited until after dark to check the spark on the plugs. With the plugs in the wire, but out so I could see them, the spark jumped from the base of the wire at the power pack to the one above it. Same thing happened when I switched out to try the bottom plug. Back in the motor, there was no jumping at the wire, and I could not see anywhere that the spark was escaping. Any chance that this would indicate bad wires, or just an idiotic wannabe do it yourselfer?
 

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Okay, so I've tried playing with different things to try and narrow down the issue.

After checking, Fuel delivery is not the issue and it wouldn't fire with starting fluid. I don't have a way to check compression, so I don't know about that.

I waited until after dark to check the spark on the plugs. With the plugs in the wire, but out so I could see them, the spark jumped from the base of the wire at the power pack to the one above it. Same thing happened when I switched out to try the bottom plug. Back in the motor, there was no jumping at the wire, and I could not see anywhere that the spark was escaping. Any chance that this would indicate bad wires, or just an idiotic wannabe do it yourselfer?
Sorry man you said it not me!, spark doesn't escape! lol to the point it won't start.

If it's sparking its sparking, pull the plugs, hook one up to the plug wire hold it firmly against the block and turn the engine over if you see spark then try the other wire with the other plug.

As long as the plug is in good contact to the block it won't shock you shortest path to ground is the block.

If your sure it's not fuel and it has spark then it's not looking good, but I don't think you lost compression due to sitting.

Where you located?
 

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I'd guess flooding being the problem.
Setting for an extended period might have gummed up the float valve
allowing too much fuel to be passed through the intake. Doubt you lost compression,
proved you have spark, plenty of fuel, probably too much.  :-?
 

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Discussion Starter #6
Ha! It's all good. If I can't laugh at myself, then it's time to stop fishing! Creek runner, I'm in Central Fl in a little town that thinks it's big called Sebring.

I'll try holding the plug against the block and see what happens. Brett, I'll see what I can do about the float valve to see if the issue is there. As I understand it, the carbs in these smaller engines are easier to gum up than the larger ones.

Thanks again, all!
 

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I'd guess flooding being the problem.
Setting for an extended period might have gummed up the float valve
allowing too much fuel to be passed through the intake. Doubt you lost compression,
proved you have spark, plenty of fuel, probably too much.  :-?
If it was stuck open then it would be flooding the engine like Brett is talking about, however you would know because the primer bulb would never get fully hard and gas would run out of the throat of the carb. Also if you pulled the plugs after trying to crank it the spark plug would have tons of fuel on them to the point you would get a drop or two of them.

Did you rebuild the carb? I'm betting you have a stuck needle float in the closed position and gummed jets. Pull the carb it's only 2 nuts.
 

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Aw come on Creek it is soooo much more fun to pull all of the plugs and then have a buddy (preferably one that has a sense of humor and is smaller than you) hold a lead ungrounded while you crank it over.  You will instantly know if that lead is getting juice! LOL!

Creekrunner wrote:
"Did you rebuild the carb? I'm betting you have a stuck needle float in the closed position and gummed jets. Pull the carb it's only 2 nuts."

That's my thought a well.  With the crappy gas we have been getting I tend to pull and clean my carb(s) several time a year.  Takes me less than 30 minutes start to finish.
 

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Discussion Starter #9
Well, I've got great spark. Pulled the carb and took apart what I could to clean it out. The float was moving freely,
But I wasn't able to get to the top of the carb thanks to a crazy looking screw that I couldn't get out. I think they call it a tamper proof screw... It's a star but with a piece in the middle so you need a special tool to get it out. Mechanic looking at it on monday. I'll update then in case someone else can use the info later.
 

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Discussion Starter #10
Well my buddy at Highlands Outboard came out to take a look at my 15 hp anchor and confirmed the worst. Compression is dead in the bottom cylinder, only 45 in the top. The coughing I was hearing was the air escaping the cylinder and when I could get it running, he said it was likely only running on one cylinder. So there you have it if anyone needs to match up symptoms with my experience.
 

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Ouch! Sorry to hear it. He say why? Blown gasket, scored, hole? Be nice if you could just drop on a new gasket, but...

Swamp
 

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Well my buddy at Highlands Outboard came out to take a look at my 15 hp anchor and confirmed the worst. Compression is dead in the bottom cylinder, only 45 in the top. The coughing I was hearing was the air escaping the cylinder and when I could get it running, he said it was likely only running on one cylinder. So there you have it if anyone needs to match up symptoms with my experience.
Sorry to hear that.

1st rule is always to do a compression check 1st before any trouble shooting begins. If not you chase the problem like you did.

2nd you don't lose compression in both cyc. from sitting for 2 months. something had to be wrong with the engine prior.
 

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Discussion Starter #13
That's my guess as well. I didn't think that I was getting enough power out of the motor earlier this year. When the mechanic looked at it, he noticed some discoloration and paint peeling consistent with overheating. So you're probably dead on. There was likely some warping in some small amount that managed to finally go completely when the engine started bogging down and didn't like restarting last month.

Lesson learned. It's not the end of the world. There's a small lake right a street over from me that I can fish all day with just the trolling motor while I wait for late feb/early march for the SUV 17 to be built :)
 

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Discussion Starter #14
Swamp skiff, he said they wouldn't be able to diagnose it without taking it apart, but that with the overheating evidence there was a good chance it would need to go to a machine shop to be re-drilled. Total cost wasn't worth the price of the motor since he was going to have to out source the machine shop work.
 

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Yeah, that's a bummer. If machining and parts are not to much it might be a fun project to learn on in the future.
 
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