Motor trouble

[fishnsled]

Last weekend at the end of the day on the run back to the launch my motor lost power, bogged down, and then picked up again. I thought it might be a dirty fuel filter so I changed it. Out on the lake yesterday I had no top end. Motor sounded OK, started OK, got up on plane but a bit sluggish, but when WOT I could only get 4000-4200 RPM and 31-32 mph. Usually I'm about 5300 and 41-42 mph. Maybe a bad fuel filter? Since there was a slight problem last weekend I'm thinking not but who knows.

 

So the question is what might be causing this, is it OK to run like this for couple more trips? (This late in the season, I would imagine that I won't get the boat back anytime soon with all the winterizing going on at the mechanics) Is it something I can fix myself? The motor is a 2002 Mercury 2 stroke 115hp. Going out to have a look to see if a pinched the fuel line or if the filter is leaking fuel,(if leaking fuel might be sucking air?) didn't notice that happening yesterday. Maybe a fuel pump problem? Your input is greatly appreciated.

 

Thanks!

Edited October 28, 2010 by fishnsled

[Roy]

Will, maybe you can blow it out with Seafoam? Not good at this but it might be an option....it certainly won't hurt anything.

[fishnsled]

Will, maybe you can blow it out with Seafoam? Not good at this but it might be an option....it certainly won't hurt anything.

 

Was going to grab a can of Seafoam this afternoon on my run about town Roy. Was thinking it might be some bad gas but that might have the motor running rough. Thanks for the input Roy.

[mercman]

i did a web search with the symptoms you describe and a lot of the forums point to a fowled plug causing a cylinder to misfire or not fire at all. or dirt in the gas that has plugged a jet in the carb.They suggest you clean and regap the plugs or replace them first.

[irishfield]

My 115 Johnson two stroke oil injected use to do that once in a while and I found it was a loose spark plug wire socket.

[Sinker]

Mine did the same thing in the spring. I did the fuel filter/line and it was gone. I also run seafoam thru mine twice a year. I put a full can in 25L of fuel, and let 'er smoke it out.

 

I think the ethanol eats the old fuel lines. My new one I got said it was safe for use with ethanol.

 

S.

[aplumma]

You need to be careful if it is a two stroke running it lean because of lack of fuel/oil can melt a piston. You will more than likly though find you have dropped a cylinder either from lack of spark (bad plug,wire,coil) or compression on one of the cylinders. I would do a compression check and replace the plugs/coil/wire test before venturing out again.

 

 

Art

[mbac31]

I would lean towards the Plug issue. Check there first. Remember to label them all as to remember which one goes where to easily identify a bad cylinder. I would suggest running this http://mystarbrite.com/startron/ through your motor. I have always run Quickkleen and seafoam but this stuff sems to work the best. Couldbe a coil but never hurts to replace the plugs and filter yearly anyways. Funny for it to go all of a sudden though.

[Ron]

Mine did the same thing in the spring. I did the fuel filter/line and it was gone. I also run seafoam thru mine twice a year. I put a full can in 25L of fuel, and let 'er smoke it out.

 

I think the ethanol eats the old fuel lines. My new one I got said it was safe for use with ethanol.

 

S.

 

 

 

Ding ding ding ding.......we have a winner

 

I would have to agree with this one Wil. Even though you changed the fuel filter, be sure to check your fuel lines and make sure they are rated for ethanol. The fuels lines will appear OK on the outside but they deteriorate on the inside and eventually collapse.

Edited October 17, 2010 by Ron

[John Bacon]

I have had problems with my Suzuki loosing power at top end a few times. Twice it was because of faulty spark plugs; I swtiched from NGKs to Champions as per the marina owner recommendation and haven't had this problem since. Another time it was the fuel filter; a good cleaning solved that problem.

 

Take a look at the plugs. In my case the fauly plugs were black and wet while the good plugs were dry and grey.

[fishnsled]

Thanks for the replies everyone. Got busy with other things today but will pull the plugs tomorrow night and have a look at them. Will also have a look at the fuel lines. They seemed OK when I changed the filter, no residue coming off, but will check a couple other connections. With the fuel lines, what should I be looking for in terms of breakdown of the lines? I'm running NGK's and have since I got the boat, maybe a time for a change. Thanks again!

[fishboy]

I had a plug with a hairline crack in the insulator that caused that sort of issue.

[Tom McCutcheon]

I am also with all the others who have said it is likely a fuel problem. One other thing to check is the water seperator if you have one. Very tempermental on our Merc 135 Opti. Same symptoms as you have mentioned and needs yearly maintenance.

 

Tom.

[johnnyb]

Could it be water or excessive ethanol in the fuel itself? Our little fourstroke was doing exactly what you describe this past summer, and it ended up that someone had run a tank of "regular" octane through it, and the ethanol was mucking everything up. We only run premium to avoid this

[Fish Farmer]

I was just at a marine mechanic seminar and the thing he talked about was the biggest thing lately was issues with the ethanol fuels. He recommend running stabilizer on every fill up.. Gas these days have only 1 month shelf life. The octane drops off and causes fuel to slow burn and will melt pistons. He also said some injectors will clog with old gas that has been left with-out stabilizer. It also harms some certain plastics, gaskets.

fishnsled, I hope this is not your case, but I would try a compression test.

He said in the near future there talking jumping to 20% ethanol from 10%

[Headhunter]

Will, I would probably just blame Cliff, but that's my pat answer for most things these days!

HH

[fishnsled]

Will, I would probably just blame Cliff, but that's my pat answer for most things these days!

HH

 

Cliff was with me when it first acted up.....

[fishnsled]

Checked the fuel lines again and were still firm from the weekend, don't think it's a line problem but maybe while running. Pulled the plugs and one plug was wet and another was questionable, these were the bottom 2 plugs. The top 2 were fine. Got a compression tester coming on loan and will do the test later in the week. I've put in last years plugs for now but hope to grab a new set later in the week. If the compression is good and still having problems, I'm guessing a coil would be the next thing to check? Can the be tested or do you just replace them? If compression is bad then I guess my season just got cut short. PLEASE let it just be a bad set of plugs....

[discophish]

My guess would be electrical ... just a guess. You can test a coil for resistance and measure to spec, but not always indicative of proper function. Hmm. Something is happening to that spark journey of yours from the source down to the little electrodes. A pair? Hopefully not the processor! Hope you get it sorted out Will.

[Sinker]

My fuel lines looked brand new when i replaced them. I tried all kinds of stuff to make it run right, and finally broke down and bought the new line. Its been running like a top ever since. When I put the new lines on, I didn't think it was going to make a difference. I was about to change the coils.

 

S.

[fishnsled]

Update - Compression test done and everything checked OK. Fired up the motor (in the driveway with the garden hose) with the old plugs I put in and seems to be running better. Water test on the weekend. I'll be replacing the plugs with new plugs on the weekend. If all runs well then that will be it for this year, hopefully. For next year I will replace the fuel lines just as a precaution. Seems like that might be the next problem so might as well avoid it be for it happens. Thanks for the help and great advice.

Will update after the weekend.

[fishnsled]

Just a word of caution, Fishnsled. When I had a similar problem with an outboard, I spent a night tearing the fuel system apart, cleaning everything, put it back together, new plugs, tuned the air/gas mixture, and she ran BEAUTIFULLY with the prop in a garbage can full of water.

 

The next time on the lake, when it had to push the weight of the boat and two passengers - bogged down.

 

I agree with you here. If it runs great on the weekend, I'll be thrilled. I'm very happy that the compression is good on all cylinders and anything else should be some what minor in comparison. Fingers crossed....

[fishnsled]

Boat seemed to be running fine. Top end was back, punched up on plane, things seemed to be OK until the end of the day. So I took the motor in for a closer inspection by my mechanic. Seems the gasket has leaked and water got into the lower cylinder. No signs of water before the last trip. Looking at a power head rebuild job or a new motor at this point in time. Will pick up the boat this weekend and do some thinking on this one over the winter months. Bring on the hard water!! Or if you have a spot in your boat, shoot me a pm. lol!

[Spiel]

Boat seemed to be running fine. Top end was back, punched up on plane, things seemed to be OK until the end of the day. So I took the motor in for a closer inspection by my mechanic. Seems the gasket has leaked and water got into the lower cylinder. No signs of water before the last trip. Looking at a power head rebuild job or a new motor at this point in time. Will pick up the boat this weekend and do some thinking on this one over the winter months. Bring on the hard water!! Or if you have a spot in your boat, shoot me a pm. lol!

 

 

Well that sucks big time Will !

 

While I have seen your boat and motor I really didn't scrutinize it for age but it all seemed fairly shiny and new.

Is there no warranty time left on the motor?

 

I'd be happy to take you out but my boat ain't leaving the driveway anytime soon.

 

 

[fisher]

Well that sucks big time Will !

 

While I have seen your boat and motor I really didn't scrutinize it for age but it all seemed fairly shiny and new.

Is there no warranty time left on the motor?

 

I'd be happy to take you out but my boat ain't leaving the driveway anytime soon.

 

I had Discount Marine do a rebuild on my Merc 40 HP motor a few years ago, and other than having to go back the next year due to some issues with one of the cylinders(which they fixed for free), it has been running good ever since.