New member needs troubleshooting help

[runnin rooster]

I am new to this board and am hoping to get some diagnosis/repair help with my outboard motor. My goal is to get it running well again without sinking a lot of $ into it, because simply put, the $ aren?t there and the boat is not worth it. I have had an 88 Bass Tracker with a 45hp ?Mercury Classic 50? on it for several years. We are not convenient to good fishing/boating waters so any excursion is an all day event. Unfortunately with two young kids and two jobs, it does not get out much, usually 3-4 times a year. The rest of the time it sits in the open under a well fitting, properly pitched cover.

I will try to provide all relevant information so excuse me if I get long winded. When I bought it about 10-12 years ago, at the advice of the owner of a local marina, I disconnected the oil injector and mix directly in the tank. I always mixed in some Seafoam in the last tank of the year. It ran well until late 08 when it started intermittently running at only about half RPM, but would suddenly kick in and run fine the rest of the day. It became progressively worse. In early 09 I changed the plugs and wires with no improvement. Shortly thereafter I put in the marina and they replaced the power distribution box, new battery and a couple other things to the tune of $700. The boat is likely not worth much more. It ran great the few subsequent times I got it out last year, and a couple weekends ago, my first fishing outing of 2010. That trip was entirely on last season?s gas and the motor ran great.

But Sunday I took the kids tubing. I filled the tank and mixed in some Shell 2 cycle outboard oil at 50:1. Again it started out running great but about an hour into tubing I noticed an occasional momentary reduction in RPM at high speed. I would term it a ?soft? miss, smoothly dropping a couple hundred RPM for a few seconds then smoothly coming back, not a sudden cutting in and out. It still idled well and pulled strong off idle. I pulled the cover and could see nothing obviously wrong. As I said, boating is an all day commitment and the kids were having a blast, so we kept it up, admittedly not the right thing to do. Gradually this ?soft? miss came more rapidly and at lower RPMs. By the end of the day it was not idling well. It would idle smoothly, then drop off idle to almost stalling but never did, then come back to idle RPM. I would still characterize it as a ?soft? miss but it was so pervasive the motor would not pull strongly off idle. It still planed out but the motor was obviously lacking something and running about half speed, even more noticeably under load.

Any suggestions on where to start troubleshooting? I would like to avoid putting it back in the marina if possible. I can not afford to sink several hundred dollars into it each season, especially as little as I use it. I am mechanically inclined enough to be dangerous to a car or motorcycle, my experience ranging from basic maintenance up to replacing a few heads, clutches, and brakes. But I know little to nothing about outboards.

 

[Fuzzytbay]

Re: New member needs troubleshooting help

Intermitten issues are always a treat to solve. When you had the cowl off, did you put your hand on the water jacket? I noticed that you never mentioned changeing the impeller in all the time you have owned the motor. Over heating can cause the problems your describing. In colder water, the engine cools better, and might not get too hot, yet in hot weather, the water may be quite a bit warmer, and the motor doesn't cool enough and starts to overheat. Overheating makes metal expand, so the engine has more friction in the cylinders, making it hard to work, or as you see a drop in rpms, for the same throtle setting. This also becomes a bigger problem, since the higher friction, makes more heat, and the motor getting hotter and hotter. Too much of this, and it will score cylinders, causing rough running, and eventually a blown or melted piston crown, or seized piston. I'd pull the plugs and look at them. That would be the first step, eliminate this issue, and move on to fuel related items next.

 

[runnin rooster]

Re: New member needs troubleshooting help

Thanks Fuzzy. I did have the impeller changed last year while it was at the marina. Sunday it was peeing good, so hopefully overheating is not an issue. This problem is not intermediate. It started Sunday with a momentary miss at high RPM and progressively got worse all day. Once it started, it did not improve and by the end of the day was consistently bad. I figured the plugs would be the place to start. Do these motors have fuel filters?

 

[runnin rooster]

Re: New member needs troubleshooting help

My fingers are crossed that I may have solved this one, at little cost like I hoped. Last evening I removed and drained the tank, changed the gas filter and plugs, all things it likely needed. It started and ran fine on the muffs. Fortunately the cover was off when I ran it. I noticed a pin stream of water spraying from a small hose going into the top of the engine. It was spraying on the ignition wires. And as I have now been told, was likely getting sucked into the carbs. All I had to do was shorten it a half inch or so to eliminate the leak, literally a 10 second fix. I did not notice this on the lake because the motor was off and had been sitting for a while when I pulled the cover. I will get it out this weekend and my fingers are crossed.