1994 yams 225, one won't go over 4300 rpm.

[regulator express]

twin engines, one will go up to 5200 rpm, the other only up to 4300-4400 rpm. Both were recently checked out and tuned carbs. Run well from 1000-4400 rpm, but only one goes up to full rpm. Props are the same. Both idle a bit rough. Boat/engines have 450 hours, but the engine that doesnt rev all the way has a new powerhead in 2002 (8 hours), new gears, new fuel pumps, new oil pump all done in 2002. These engines were only used 5 times in the last 2 years. I recently bought the boat.

 

[jrod8v92ti]

Re: 1994 yams 225, one won't go over 4300 rpm.

lots of things to check on engine but hows your fuel supply?<br />primary filter/coaleser, any kinks in the fuel line? <br />you've done alot already but i would say check the above and put some hours on the new powerhead and take comp readings to ensure all is well.

 

[rodbolt]

Re: 1994 yams 225, one won't go over 4300 rpm.

5 times in 2 years is neglect.<br /> take all your spark and compression readings to insure mechanical sealing then go through the carbs again.<br /> sounds like they are plugged up again<br /> also post a model # so we can tell if you have a 2.6L or a 3.1. without knowing that all else will be a shot in the dark.<br /> the 3.1 has some special issues

 

[regulator express]

Re: 1994 yams 225, one won't go over 4300 rpm.

rodbolt or others, they are the 3.1 gas guzzlers....76 deg.<br />After a few more test runs 30 minutes each, the rebuilt engine still wont go over 4300 rpm with the throttle fully pushed. (other goes up to 5200) Its using a ton of oil (2x) compared to the other, but the rpms wont go up. The other engine just occasionally runs hot, alarm goes off, stop the boat, and then later is fine again.

 

[rodbolt]

Re: 1994 yams 225, one won't go over 4300 rpm.

5 times in two years. its suffering from neglect.<br /> is this a 2.6L or a 3.1?<br /> when was the last time it ran correctly?

 

[regulator express]

Re: 1994 yams 225, one won't go over 4300 rpm.

On the engine that won't rev all the way, the primer bulb is "softer" than on the other engine.<br />Also, could the tps be a problem? Why do you say the plugs might be fouled again? Why so much oil use on one engine? On an engine that overheats only after higher speed long runs, is that the thermostat?.....<br />thanks for all

 

[phatmanmike]

Re: 1994 yams 225, one won't go over 4300 rpm.

i am no YAM expert, so ignore me if i sound stupid....<br />he says that it only has 8 hours since new powerhead and its using 2X the oil.. is it still in break in mode? do yams even have break in mode?<br /><br />an engine that overheats could be lots o things. i had a 115 that would overheat at high speeds but fine at low speeds, i took it apart and found handfulls of sand and silt inside water jacket impeeding the flow.<br /><br />as to your motor not going WOT, are your throttle plates open all the way? check the simple things first.

 

[Ray Neudecker]

Re: 1994 yams 225, one won't go over 4300 rpm.

As rodbolt said earlier, lack of use is often the same as neglect. You need to start at the fuel tanks and go all of the way through the carbs after checking compression and fire. Rigs which have sat up do not allow you to skip around in your trouble shooting. Continued operation before correcting the problems will likely end up in very expensive repairs. You also need to service the cooling system. These are very common problems where the rig has not been used. It also often means they have not had the service kept up on them.

 

[regulator express]

Re: 1994 yams 225, one won't go over 4300 rpm.

thanks ray, rod, guys,<br />on the overheating engine, I'm going to replace both t stats just to be sure. If it only overheats at high rpm, then it is probably due to restrictions in the cooling passages right? If so, how do I flush out the passages? Can it be done? Also, I assume the poppet valve is ok, otherwise the overheat would be at low rpm right?<br />Should I bother with the "temp heat crayon sticks" like to the manual suggests?<br />Thanks...

 

[rodbolt]

Re: 1994 yams 225, one won't go over 4300 rpm.

if after a full cooling system tune up it still has a problem look for a broken pencil zinc in the block. sometimes the zinc breaks off and lodges sideways in the block. I have had 3 in the past year.<br /> You have to remove the head to access it if its broke. otherwise they are under the tear drop shaped covers on each head and the side of the block.<br /> good luck and keep posting

 

[regulator express]

Re: 1994 yams 225, one won't go over 4300 rpm.

Rod, you are so helpful to all of us trying to get out on the water. Much appreciated. I know time is valuable for everyone. Thanks.<br /><br />Ok, what exactly would you include in a full cooling system tune up? If the waterpump was changed (#1 engine) in Aug of 2002, not used more than 6 times since then, also left in the water 2 winters, is it still fine? (overheating engine at high rpm only)

 

[rodbolt]

Re: 1994 yams 225, one won't go over 4300 rpm.

it is rubber. they can fail with age regardless of use. good thing about a yamaha is if the bolts are not stuck and I am feeling ok I can change the pump in 45 min. if after testing/replacing the pump, tstats ,and pressure valve grommet I would pull the heads and look for the pencil zincs. if they have never been replaced odds are one has broken off and is lodged sideways in ths cooling passage.<br /> good luck and keep posting

 

[regulator express]

Re: 1994 yams 225, one won't go over 4300 rpm.

I changed both thermostats in the overheating engine. Also, checked the spring loaded plastic valve "poppet". It just pushes in when water pressure is on it right? It seemed to be fine, but it had some sand and salt buildup around it. Cleaned it off, reassembled it and seems good for now. I tested it for 15 minutes....no leaks, probably not long enough to see if it overheats anymore. In the past, it only overheated (alarm) after 20+ straight minutes of near wot.

 

[regulator express]

Re: 1994 yams 225, one won't go over 4300 rpm.

It overheated again! After only 5 minutes running at 3500. Then after 5 minutes cooling, and the buzzer still going, i start it and it cools right down back to 125 from 200 deg. Rest of trip fine open throttle for 30 minutes. What gives? if water pump was bad, it wouldn't work so well for 30 minutes and another time for only 5. (only to corect itself 5 minutes later).<br />UPDATE, used the boat again today, no overheat. I'm sure it will happen again. WHHHHY?<br />Thanks.

 

[regulator express]

Re: 1994 yams 225, one won't go over 4300 rpm.

Please keep in mind, the overheating engine is NOT the one that has trouble with RPMs. the overheating engine runs full rpm and idles well.