Merc 15HP 4 stroke motor problems (Long)

TinBoats.net

Help Support TinBoats.net:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

bunktheclown

New member
Joined
Jul 12, 2013
Messages
4
Reaction score
0
Hello everyone. Fairly new member here hoping to get assistance with a motor problem.......

2003 Mercury 15HP 4 stroke short shaft.

Sat for about a year and 1/2 before I tried to get it running over the last week. Before I parked it, I drained all the water- disconnected fuel tank, replaced impeller, changed oil, gear lube etc.

It started with the carb leaking when I tried to start it (forgot to run all the fuel out). So I bought a carb rebuild kit and replaced all the gaskets/ seals, float. Blew out all the jets and anything else that could have had gunk in it. Also replaced the fuel filter and lines. Connected up a tank of fresh gas and pulled and pulled but Nothing.

Replaced both spark plugs and it finally started but very rough and quite a bit of smoke. One thing I noticed was no water peeing out the motor. I shut it down and started in on troubleshooting that.........

Checked the water lines and found some gunk in the line so I blew them out with compressed air. I then pulled the thermostat housing to check to make sure it was working..... Pan of water on the stove confirmed it was working correctly. Pulled lower unit and checked impeller just to be safe. Everything looked ok so I re-lubed the shaft and put it all back together.

3-4 pulls and it again was running, but badly. I see what appears to be exhaust coming out of the water pee hole???? Then comes water but not a very strong stream. Shut it down and check all hoses and lines etc.

Fire it back up again and the same thing, exhaust out of the water pee hole for a few seconds followed by water. Now the engine will only idle. Any throttle and it dies, no matter if the choke is on or not. I start it again and same thing , exhaust followed by water and it's just spitting at idle, not a strong stream.

I feel like I have 2 problems here but not sure where to go. I have no other fluid leaks that I can see. Any help would be appreciated.


Thanks!

-jb
 
Just a few ideas/thoughts?
1. Did you check the impeller for the water pump?
2. Usually it's not the spark plugs on a four stroke. They do not foul like two strokes.
3. Use new gas. The shelf life on today's gas sucks and then you have ethanol issues.
 
[url=https://www.tinboats.net/forum/viewtopic.php?p=322447#p322447 said:
Gotem » 15 Jul 2013, 14:15[/url]"]Just a few ideas/thoughts?
1. Did you check the impeller for the water pump?
2. Usually it's not the spark plugs on a four stroke. They do not foul like two strokes.
3. Use new gas. The shelf life on today's gas sucks and then you have ethanol issues.


1. Yes and it was installed correctly and no broken or worn vanes

2. I didn't figure it was the plugs but just trying to eliminate everything that can be easily replaced

3. One of the first things I changed. I am in California and ethanol sucks lol

Thanks for the ideas.
 
There always needs to be some tuning after a carb re-build, I don't know what's adjustable on this motor, nut the low speed needle is going to have to be dialed in for it to run well, manual should outline process. Make sure all waterways are clear. Make sure oil level stays the same. Just run it to tune the carb and dont worry yet about the smoke, it's probably varnish from old fuel and all the stuff you used to clean the carb. If it is consuming oil that's another issue, but just get the carb tuned and worr about exhaust later.
 

Latest posts

Top