2003 90hp 2 stroke has very little power

[dcducks1]

My 90hp 2 stroke was running fine on the way back from a fishing trip and then it just dropped off dead. Put it in neutral and fired it back up with the hit on the key. Gave it throttle and just as it got on plane, it did it again. I had gas, bulb was tight, hit the key again and it fired right up. I wasnt far from the boat ramp so I idled over. Upon inspection at the house. I saw the red power wire coming off the rectifier was melted along with a couple yellow wires that were touching it. The red wire was blazing hot after trying to start it at the house. I changed the rectifier and went ahead and put new plugs in. I noticed that the rubber line that goes from the engine to the top of the fuel pump and had been blown off and when I went to put it back on, I noticed the straight nylon insert looked burned. I pulled the line off because it was looking dry rotted or cracked and I found the nylon elbow on the top of the fuel pump looked burned too. I rebuilt the fuel pump just to make sure that there wasn't any debris in it. I bought a new rubber line and the nylon fittings and installed them. Took it out today for a test run and it will get the nose up but will never get on plane. Feels like about 1/3 power. It missed once and I could tell the rubber hose for the fuel pump came off again. When I checked, the straight nylon adapter looked burned again. What gives?

 

[dcducks1]

Re: 2003 90hp 2 stroke has very little power

Just to mention, I always had a steady water stream from the water pump and the motor has never overheated. I use Stabil in every tank and overall take very good care of this motor. Waiting for the nylon fittings to come in and racking my brains trying to figure out what is wrong with this motor. I will do a compression test on the cylinders today and put an inline spark tester to see what I can find. Does anyone know the compression I should be seeing on this motor?

 

[dcducks1]

Re: 2003 90hp 2 stroke has very little power

Well, I was hoping to have gotten some expert input by now, but since I haven't I went ahead and kept doing some troubleshooting. The top and bottom cylinders are reading about 120 psi, the middle cylinder.........nothing! It looks as if I have found the culprit. I was hoping that maybe it was a head gasket that would need replacing which would be an easy and cheap fix, but when I pulled off what I thought was the head plate, I found that it is just the water passages and you can't get to the psitons. Soooooooo, my thinking is that the heat must be getting past the rings and making it's way back behind the piston where the air that is supposed to be operating the fuel pump is getting hot enough to melt the nylon fitting. Am I on the right track? Any idea what a ring job will run on this motor?

 

[TD_Maker]

Re: 2003 90hp 2 stroke has very little power

Your Mercury motor does not have traditional Head Gaskets as you found out. The "water passages" are called exhaust plates which often leak and allow water into the cylinder. What color was the spark plug? Was it clean? Did any water come out of the spark plug hole? What did the gaskets look like (between the exhaust plates?) Is the inner exhaust plate cracked? Before I jumped into a rebuild job, I would eliminate the easy stuff like this.

Just curious, when you removed the exhaust plate bolts, were you able to get them all out without breaking any of them off? On my motor, I broke 8 of 24 bolts completely off inside of the head.

 

[dcducks1]

Re: 2003 90hp 2 stroke has very little power

Spark plugs are clean with no sign of any water. The gaskets were in tact and in relatively good shape. All bolts came out with no problems. The only think I found that looked bad was the thermostat which looked as if it hadn't been working in some time. My biggest worry is the melting of the nylon fitting. I must be getting some serious heat around the piston and back to that fitting to melt it. That's why I'm thinking it's a problem with rings or worse. The engine makes no strange sounds such as grinding, etc., the only thing it does is run rough, with no power, and when it misses, it blows that line off from the fitting to the top of the fuel pump.

 

[dcducks1]

Re: 2003 90hp 2 stroke has very little power

I guess at this point the only thing I can do is pull the powerhead off and split it in half. I'm wondering if a broken reed could be causing this problem. I have zero compression in the middle cylinder so I am guessing that the rings are bad if not the entire psiton. Any thoughts before I start tearing this apart? Would it be better to rebuild the powerhead I have or buy a a powerhead that is already put together?

 

[carholme]

Re: 2003 90hp 2 stroke has very little power

Bad reeds can cause blowback through the carbs and sometimes you may hear sneezing but if you have nothing on the one cylinder, I doubt you have much choice other than to have a look and see what problem there is with the rings, piston, cylinder walls etc.

Do you have a manual for the engine? If not, send me a PM with an email address and I can send you a copy.

What is the engine s/n?

Gerry

 

[dcducks1]

Re: 2003 90hp 2 stroke has very little power

I am waiting on digging any deeper until I have talked to more friends, experts, mechanics, etc and gotten my hands on a manual. I have looking at remanufactured powerheads with the idea of a warranty making me sleep easier. This would also be easier to move the accessories off the old and onto the new head which will save some time. This motor only has 202 hours on it which is a shame but things happen. Still don't have a dirty taste in my mouth over this Mercury...yet! Still holding out hope that it gets fixed and lasts many more years for me. More to follow as I dive into this rebuild.

 

[TD_Maker]

Re: 2003 90hp 2 stroke has very little power

Carholme knows what he is talking about. He is one of the GURUs on the Forums. I can only give advice because of previous experience I had with my own motors.

 

[Yesterday]

Re: 2003 90hp 2 stroke has very little power

Carholme knows what he is talking about. He is one of the GURUs on the Forums. I can only give advice because of previous experience I had with my own motors.

I was going to say the same thing. I'm not sure how much more expert you'd need than Carholme. Guess some folks don't take a minute to read poster's profiles. Those whose posts he chimes in on are fortunate.

 

[dcducks1]

Re: 2003 90hp 2 stroke has very little power

Update. Pulled the head off to look into the exhaust ports and the #2 piston is missing chunks and has very bad scarring down the sides. I have stripped all of the accessories off and pulled the powerhead. I am buying a rebuilt powerhead instead of trying to fix this one. The problem is that I am having a hard time a) finding someone who can rebore or clean out that cylinder, b) someone who has the time to do it. A rebuilt head seems like it will get me back on the water faster and comes with a 1 year warranty.

 

[TD_Maker]

Re: 2003 90hp 2 stroke has very little power

I kind of figured you were going to find some scarring. There is a guy down here in Florida wh
o does rebuild these things, and the motors are super-strong when he is done. Outboard Motors - Sales and Service (call and ask for Ron)

 

[jasonbailey]

Re: 2003 90hp 2 stroke has very little power

If you decide to rebuild, check out Ritchie Automotive Machine in Capital Heights. He planed the head on my old OB some years back. It maybe worth a call to him. He also did some head work for my pickup. He does pretty good work.

 

[dcducks1]

Re: 2003 90hp 2 stroke has very little power

Bought a rebuilt powerhead from OneMarine out of Pennsylvania. I installed it on Friday and had it running by Friday afternoon. So, here's what I have done: Replaced powerhead, new plugs, rebuilt all three carbs, rebuilt fuel pump, new inline fuel filter, new screw on fuel filter, changed several hoses and fittings, new water pump and lower unit gaskets, new lower unit lube. Hell I even replaced the decals on the cowl. It runs, idles, but has no power when in the water. If I engage the throttle only (not in gear), I can get it to rev to whatever I want. When I engage the drive....nothing. No guts, no power. I have adjusted the timing and resynched the carbs probably 5 times and am pulling my hair out. I am running about 100-1 for the fuel/oil mixture to break it in. It hesitates and misses at times which cut either be fuel or timing. The compression on all cylinders is a little less than 120 but the rings haven't had time to seat yet. The SELOC manual is NOT my friend right now. I would have rather paid $200 for an engine-specific manual than the book that cover from 2hp-225 for 10 years. Very frustrating. What am I missing? I would have an expert do the adjustments right now if I could find one. Everyone is saying at least two weeks before they can touch it.