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Yamaha 225

I have a 1995, 225hp salt-water series Yamaha. So far I have had the motor rebuilt because it had seized. After that it still did not run properly and was told it needed a new CDI which I purchased and had installed, then it was dirty fuel so I had that replaced, it still did not work correctly. Next I was told the spark plugs and leads were the problem and these were replaced, but the problems still exists. The problem is that on the ear muffs the motor runs fine revs out really well, but the moment it goes into the water it will not rev past 2000 rpm. Any suggestions on what I can look for or try myself before I let another boat mechanic near it and I spend another obscene amount of money not getting the problem repaired? Thanks for any suggestions
 
Is the engine missing and running rough, or just won't run up past 200 rpm?
First thing is to do a compression check. That takes care of one of the most basic issues that could cause your problem. If compressions are good, how are the fuel pumps? If they are good, how are the carbs? Need to check all those things before getting into the next phases.
 
Is the engine missing and running rough, or just won't run up past 200 rpm?
First thing is to do a compression check. That takes care of one of the most basic issues that could cause your problem. If compressions are good, how are the fuel pumps? If they are good, how are the carbs? Need to check all those things before getting into the next phases.

Hi thanks for your suggestions. The engine is fine on the muffs, but when put in the water won't rev past 2000 almost like it is limp home mode. Compression 115 to 120
 
I assume that it is carb'd? If so, I don't believe that it has a 'limp mode'. An engine that is almost completely dead might rev high with no load, but that tells you almost nothing. If it only goes to 2000rpm under load then you have a loss of power issue. Some other things to check -

Fuel Pumps - (these are a known maintenance item). Unbolt them from the block (2 x 10mm bolts) but leave the hoses connected, and then squeeze the primer bulb whilst watching the pumps. If they leak, the diaphragms are damaged.
Carbs - strip and clean until they look like new using lots of compressed air. If it isn't missing when you run it, the carbs are not so likely.
Timing - has anyone checked that the rebuilder got the timing correct and is the timing advance hooked up properly?

When you get to 2000 rpm under load, is the engine running rough, or does it run smooth but just not rev any higher?

Is the boat stored on the water or on land? If on the water, when was the hull last cleaned?
 
Hi and thanks again for your suggestions. The boat is stored out of water on a trailer. When it gets to 2000 rpm under load it starts to run rough. It is a carby model there are 6 of them. I will probably get to the boat this week or early next week and will have a look at the fuel pumps. The timing is something I had not thought of, so thanks again.
 
I have the 90 Hp (1991 and SM for P60P/70P/90P) and while they don't call it "Limp Home", they do have a "Speed Drop Function" which limits RPM at 2000 RPM and there is a loud warning buzzer to go along with it.

Two conditions can enable this protection, first is if Oil Tank (float) falls below 1/3 quart remaining and second would be a cylinder overheat (188f+) detected. I believe larger engines also react to an over-rev condition.

I know nothing about larger Yamaha's, but would expect them all to have this self-protection feature.

Timing investigation looked like great advice, I found mine was off and correcting it made a huge difference in power available. Outboards don't usually 'lose' timing, but yours has been seriously apart for your rebuild. SM starts by confirming actual TDC1 with marks, setting throttle arms and finally with timing light at 4500+ RPM. Hope you can resolve issue without need to buy more parts.
Art
 
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