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Started By
Message
Need outboard troubleshooting help
Posted on 7/20/25 at 2:20 pm
Posted on 7/20/25 at 2:20 pm
Have a 2003 yamaha 115 2 stroke
the last two years it has only been run 1-2 times each summer, but all i had to do was put a new battery in and it would crank right up and run fine. I put 93 octane fuel in it and a can of seafoam 2 years ago.
Jump to this summer and same thing as always...new battery and it would crank right up. Brought it to the lake to run and whenever I would give it some throttle it would just bog down and die.
Brought it to local outboard mechanic in Mandeville and he cleaned the carbs and had it running great out of water, went and put in in the water and the same thing. No idle and it just bogs down and dies. I was able to keep it alive by pushing the key(choke) but that was it.
Called the mechanic, he looked and ran it out of water and once again, no problems except would stall out on idle(not new with this one) and that was as much as he would be able to help me.
So my son and I drained the fuel tank, put new non ethanol fuel in and an enzyme treatment last weekend. Boat ran in driveway, put in water and the same thing.
This weekend, we took off the fuel filter and it had a bunch of gunk in it. We bought a new one and got started in driveway and it sounded great...thought we had it!
Put in the lake a little while ago and could not even get it to stay on.
Any ideas on what the difference between on ears and in water could be?
We have a pee stream and nothing out of the ordinary???
In Mandeville area if anyone has mechanic recommendations
the last two years it has only been run 1-2 times each summer, but all i had to do was put a new battery in and it would crank right up and run fine. I put 93 octane fuel in it and a can of seafoam 2 years ago.
Jump to this summer and same thing as always...new battery and it would crank right up. Brought it to the lake to run and whenever I would give it some throttle it would just bog down and die.
Brought it to local outboard mechanic in Mandeville and he cleaned the carbs and had it running great out of water, went and put in in the water and the same thing. No idle and it just bogs down and dies. I was able to keep it alive by pushing the key(choke) but that was it.
Called the mechanic, he looked and ran it out of water and once again, no problems except would stall out on idle(not new with this one) and that was as much as he would be able to help me.
So my son and I drained the fuel tank, put new non ethanol fuel in and an enzyme treatment last weekend. Boat ran in driveway, put in water and the same thing.
This weekend, we took off the fuel filter and it had a bunch of gunk in it. We bought a new one and got started in driveway and it sounded great...thought we had it!
Put in the lake a little while ago and could not even get it to stay on.
Any ideas on what the difference between on ears and in water could be?
We have a pee stream and nothing out of the ordinary???
In Mandeville area if anyone has mechanic recommendations
14
Posted on 7/20/25 at 2:29 pm to tigertail34
quote:
Any ideas on what the difference between on ears and in water could be?
Exhaust back pressure. When on ears, exhaust is free flowing so engine has no resistance. What are your rpms on ears? Did you do basic compression check?
Posted on 7/20/25 at 2:38 pm to headedwest21
quote:
What are your rpms on ears? Did you do basic compression check?
Not sure how to run a compression test. Mechanically inclined somewhat, but not outboard engine smart!
I can rev up and down on ears without a problem, as soon as it goes into neutral it stalls out.
I was able to get it to run at low speed in lake last week, but as soon as I would give it throttle it would bog down.
He changed the fuel ball with a new one, this one seems pretty flimsy but the last one was 20 years old and rock solid and hard to squeeze at all!
Posted on 7/20/25 at 2:45 pm to tigertail34
quote:
Any ideas on what the difference between on ears and in water could be?
As mentioned, exhaust pressure. The engine has less load running in open air than with the prop in the water.
Engines that wont accept load usually have a fuel problem, either fuel delivery or carburetor issue.
You can eliminate the tank/hose/pickup tube/etc by running the engine on a small tank with a short piece of fuel hose and a primer bulb. That will isolate the issue to either the boats fuel system or the engine. Put the lower unit in a trash can full of water to simulate being in the water and make a little exhaust pressure.
Try that and report back.
Posted on 7/20/25 at 2:48 pm to DownshiftAndFloorIt
I think the carbs need another round of cleaning
Posted on 7/20/25 at 2:51 pm to DownshiftAndFloorIt
quote:
Engines that wont accept load usually have a fuel problem
Is this something that most outboard mechanics would be able to determine?
My guy cleaned the carbs and has now basically said he can't do anything else to help me. It runs five when its at his shop...my problem that it wont run in the water?
Posted on 7/20/25 at 2:53 pm to tigertail34
Had same engine for years. Same issues as well. Mine was fuel delivery. Check fuel lines and bubble. Also check fuel tube in the tank and all connections. Good luck
Posted on 7/20/25 at 3:30 pm to tigertail34
Had something similar. The tube in the gas tank rotted out. Fixed it and problem solved
Posted on 7/20/25 at 3:34 pm to tigertail34
quote:
this something that most outboard mechanics would be able to determine?
Yes.
quote:
My guy cleaned the carbs and has now basically said he can't do anything else to help me
Id be looking for a new guy.
Posted on 7/20/25 at 3:48 pm to tigertail34
Could try running on an external gas tank.
If runs like you’d expect you have a fuel delivery issue. If runs the same as is now likely still have a motor issue.
If runs like you’d expect you have a fuel delivery issue. If runs the same as is now likely still have a motor issue.
Posted on 7/20/25 at 3:50 pm to tigertail34
Had one about that timeframe, would have same problems annually too. If you had carbs cleaned before going thru filters etc, you need to do it again as others mentioned. If you ever ran ethanol, run new fuel lines as well, stuff chews up those fuel lines.
Posted on 7/20/25 at 4:52 pm to tigertail34
Look at the strainer / pickup tube and check valve in the fuel tank. Have had similar issues as you and this was the culprit.
Posted on 7/20/25 at 5:17 pm to tigertail34
I’ve had the same problem before. Bad primer bulb on fuel hose. Especially if not OEM. Those cheap replacements don’t last. Give it a shot. On one of my four strokes motor stooped dead in the water one night. Pulled the bulb off of the hose and dropped hose thru filler cap on tank. Ran fine. Broke down and put OEM bulbs on three boats after that.
Posted on 7/20/25 at 9:51 pm to tigertail34
There are multiple filters on the way to the engine. I speak from OX66 experience, yours might be different but I doubt it. There are 3 just in the VST. There’s also one in the inlet to each injector that doesn’t even show up in the repair manual. Pull the VST and clean it, replace all those filters inside (put on a new VST gasket btw)
Posted on 7/20/25 at 10:17 pm to tigertail34
Compression check doesn’t hurt, there’s plenty of YouTube videos of how to do that. Most importantly, 1. Don’t cross thread the gauge into the spark plug hole, 2. Pull the kill cord to ensure the engine doesn’t actually start when you’re turning it over.
Inspect all of your spark plugs when you pull them. If some any are rusted it’s likely you’ve got a water jacket corroded through into the cylinder wall. Not sure about the 115s in particular but early 2000s Yamahas had some questionable alloy/castings. Symptoms will be exactly the same.
As others said, really sounds like a fuel delivery problem. Try running on an external tank with new bulb and fuel hose to start.
That will separate out whether you have an engine problem or a fuel tank/line/external filter problem.
Inspect all of your spark plugs when you pull them. If some any are rusted it’s likely you’ve got a water jacket corroded through into the cylinder wall. Not sure about the 115s in particular but early 2000s Yamahas had some questionable alloy/castings. Symptoms will be exactly the same.
As others said, really sounds like a fuel delivery problem. Try running on an external tank with new bulb and fuel hose to start.
That will separate out whether you have an engine problem or a fuel tank/line/external filter problem.
Posted on 7/21/25 at 12:57 am to tigertail34
You definitely have a lean condition where the engine isn't getting enough fuel. Could be simple as primer bulb or the fuel line used today has a liner that collapses. Replace fuel line and primer bulb. Get black cut to fit marine fuel line, I get it at ACE on the Northshore, it does not have the liner that often fails which starves your engine of gas.
If it isn't that and the carbs are clean, you could have a crankcase leak that is allowing un metered air passed the carbs and this lean condition could melt a piston quick...had it happen to me on an old Evinrude, gel seal failed between the two halves of the crankcase allowed air into the combustion chamber, would only run on the water with choke on.
If the carbs aren't clean completely, it could have a clog in a jet that is leaning out the fuel mixture but chances are it isn't that as carbs have been cleaned and it would have to be multiple carbs to create condition you are describing.
If it isn't that and the carbs are clean, you could have a crankcase leak that is allowing un metered air passed the carbs and this lean condition could melt a piston quick...had it happen to me on an old Evinrude, gel seal failed between the two halves of the crankcase allowed air into the combustion chamber, would only run on the water with choke on.
If the carbs aren't clean completely, it could have a clog in a jet that is leaning out the fuel mixture but chances are it isn't that as carbs have been cleaned and it would have to be multiple carbs to create condition you are describing.
This post was edited on 7/21/25 at 1:01 am
Posted on 7/21/25 at 8:09 am to tigertail34
quote:
Pull the VST and clean it, replace all those filters inside (put on a new VST gasket btw)
^^^^This right Here!
Posted on 7/21/25 at 8:32 am to Sea Hoss
quote:
Pull the VST and clean it, replace all those filters inside (put on a new VST gasket btw)
He has a 2 stroke, no VST on that engine
Posted on 7/21/25 at 8:55 am to GoAwayImBaitn
Another common issue right after a carb job is the linkages not working correctly or not at all. This can burn up the engine since one carb not opening fully can under-oil its cylinders.
OP needs to get it isolated to either the engine or the boat though before we speculate too much more. Could be a plugged pickup tube, could be a wrecked engine, and could be anything in between.
OP needs to get it isolated to either the engine or the boat though before we speculate too much more. Could be a plugged pickup tube, could be a wrecked engine, and could be anything in between.
Posted on 7/21/25 at 9:57 am to GoAwayImBaitn
He stated its a carb engine, vst is only for fuel injection.
Plenty of two strokes had the vst for the the fuel injection.
Plenty of two strokes had the vst for the the fuel injection.
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