'94 Yamaha 225TXRS Dies once running/fluctuates RPMS's

[Fishin with buds]

Greetings,

So i picked up this engine, had an inspection done by a Yamaha Master Mechanic, and it checked out. Cool, right...?

So got it hung on the boat, first spin and i noticed that it fluctuated RPM's in the mid to upper range. Like 3000 rpm+ i would have a 200rpm fluctuation, maybe a 3 second interval...but not all the time, sometimes it works for 20 minutes, then goes into this symptom for a while. This i can live with, but dont enjoy.

Second issue is that sometimes it will die at idle, after running for a few hours. Then, restarting is not an option for at least an hour. if i take it home, it will start first crank on the hose, but not right after it dies on the ocean. changed the fuel water seperator and got the same result, towed back again.

Oh, so heres what i did...i premixed some oil in my tank, just to make sure that my oil injection system was all working properly before i learned it wasnt the hard way. so there is about a 30:1 in the gas. second, oil tank is not hooked up. i add oil to the axuillary tank when needed. also, fuel line is old and has an old seperator and valve on it.

so the first time i took it in, the mechanic took me a week to tell me i needed to fix all "this sh*t" before he could help me, mainly dilute the oil in the gas, replace the fuel line to the tank and hook up the oil tank. fair enough. did the first two, have not hooked up the oil tank yet as, well i just havenet and i figure its only purpose is to keep me from pulling my cowling off and adding more myself, so i dont see it as making or breaking the situation. but maybe ignorance is bliss.... so my buddy had it down at the ramp, started right up, shut it down at the dock and it would not restart.

so, before i take it back to the mechanic who has yet to impress me or be helpful, i just wanted to give a cry for help and see if anyone had any ideas.

thanks and merry christmas!

 

[Ray Neudecker]

Re: '94 Yamaha 225TXRS Dies once running/fluctuates RPMS's

Sounds like the mechanic knows what he is talking about. It does sound like a fuel restriction problem. At todays shop rates, it would pay to get the basics right first before taking it to him to trouble shoot. Try testing with everything hooked up properly including the oil injection first. then try with a seperate portable tank.

 

[rodbolt]

Re: '94 Yamaha 225TXRS Dies once running/fluctuates RPMS's

I am with Ray.
carefully go through the carbs, rebuild/replace the fuel pumps, check the quick connect for the fuel inlet,if its there.
on the oil. you do realize there is a seal that MUST be replaced anytine the oil screen is lifted from the engine tank AND anytime you lift the screen any and all debris in the engine tank now heads directly into the oil pump. adding oil directly to the engine tank is strictly last resort, anything else is just, well, dumb.
you would not believe how many V yamahas I have seen blown up simply cause when the screen was shoved back in the tnk it shoved the seal down the oil pump intake pipe. just would not believe it.

 

[Fishin with buds]

Re: '94 Yamaha 225TXRS Dies once running/fluctuates RPMS's

Thank you both for your input.
Rodbolt-Interesting about hat oil filter seal on the engine tank, just going off what i can find on the net in terms of schematics(http://parts.yamaha-motor.com/?ls=outboard), is the seal you are talking about on the bottom post of the oil strainer? from the site i am looking at, its called the strainer cover gasket? does said gasket need to replaced or repositioned after removal? ill take your word for it, but isnt the oil pump in the remote tank?
assuming i f**ked this one up, is there any way to prevent the disater you are speaking of from happening, like how can i clean my oil pump out?

carbs...F! alright, thats what i was worried about. nothing like cleaning the carbs for a few hours. ill hit that, the oil assembly-as well as get the wiring done and post up some results. few days though, lights low and boats on the street.

Thanks again for the input, you guys have a good one.

 

[Fishin with buds]

Re: '94 Yamaha 225TXRS Dies once running/fluctuates RPMS's

one more point/question-replacing the fuel pump diaphrams was one of the mechanics suggestions as it could either be streched or punctured. from the same site, the schematic of the fuel pump shows 2 diaphrams, multiple gaskets, etc. can i reuse everything besides the diaphrams? should i replace whatever springs are in there-as it seems to have at least one?

now, when the mechanic checked the engine out, on his gas, oil tank, harness, gauges etc-as i had not hung it on a boat yet, should he have found any of these problems? or is an inspection just a fire up, check a few things, etc...

Thanks again.

 

[Ray Neudecker]

Re: '94 Yamaha 225TXRS Dies once running/fluctuates RPMS's

Replace the fuel pumps, rather than attempting to rebuild.
The problem might not have shown up on his fuel system or been introduced by your tank and fuel.

 

[rodbolt]

Re: '94 Yamaha 225TXRS Dies once running/fluctuates RPMS's

on the oil,
remember there are 2 pumps.
one is in the remote tank and if all the systems are working it is switched on and off by the switch in the engine tank to automatically transfer oil from the remote to the engine tanks.
the other pump is located on the port side of the block below the engine tank.
its gravity fed by the engine tank. when you remove the strainer any trash/debris in the engine tank now drops into the engine oil pump intake where it can create issues where none existed before.
if on reassembly the seal gets shoved into the tank nipple it creates issues. if on reassembly the seal does not sel between the tank and the strainer debris or water will simply bypass the strainer and drop directly into the engine oil pump intake.
thats why before removing the strainer I drain the tank then tilt the engine up.
there is also a filter at the remote tank outlet that needs periodic service.
I am with Ray on the fuel pumps, at 38 dollars each its to easy to replace them. the Prime start pump can be rebuilt.
does your engine have a pump with 2 solinoids labled A and B ? I cant remember the year change.

 

[Fishin with buds]

Re: '94 Yamaha 225TXRS Dies once running/fluctuates RPMS's

The fight is still on!

Well, actually i think we are between rounds, but noone has given up yet.

So i cleaned the carbs thoroughly and did find a small slit in the fuel line right before the starbord top cylinder(#5?) so i took care of that. I was going to take it out and see what kind of results i got by doing the above mentioned, but forgot to crank it over before i left the house, so i got a little frustrated at the ramp....no juice...F

so, took the advice of you guys and purchased new fuel pumps as well as the proper harness for the oil tank. should arrive in a few days.
before then i plan to drain all gas as some of it is old(6 months) but i have always been adding new...just want to eliminate the variable. also going to drain the oil tank, make sure the seal is correct and make sure the remote tank pump works-planning on doing this by not refilling the outboard tank at all and hopefully it will fill to the proper level...right?

anyways, once aall is good, clean and pumps are replaced, i will give it a go and see how she runs.

Thanks for the help and advice.

 

[rodbolt]

Re: '94 Yamaha 225TXRS Dies once running/fluctuates RPMS's

with the remote tank level ok,no yellow lamp, and the engine tank empty, when you turn the key ON it will sound the alarm and start the oil transfer,when the engine oil level reaches the lower mark the alarm should shut off, when it reaches the upper mark the transfer will shut off. it should be able to refill the egine tank in roughly 180 seconds, if not look for why not.
well baby is hollering at me, ill post more on it later.

 

[Fishin with buds]

Re: '94 Yamaha 225TXRS Dies once running/fluctuates RPMS's

Thanks for the help and advice. I'll keep updating as i progress on the motor.

just a question on lower unit fluid changes. do the seals need to be changed every time? or can the seals be re-used?

Thanks

 

[rodbolt]

Re: '94 Yamaha 225TXRS Dies once running/fluctuates RPMS's

as long s they are not crushed or deforemed they can normally be reused, but at .60 apiece or so I dont usually reuse them.

 

[Fishin with buds]

Re: '94 Yamaha 225TXRS Dies once running/fluctuates RPMS's

hey, since i am going through the effort, thought i might ask if there are any things to look out for when switching the fuel pumps...? or is it as simple as i think?

 

[Fishin with buds]

Re: '94 Yamaha 225TXRS Dies once running/fluctuates RPMS's

alright, so i pulled the fuel pumps and replaced them, then got curious, so opened them up. didnt really expect to find much but did find some corrosion on the inside of the outside coverplate, on the bottom end. this is where i am guessig fuel would sit when the engine was not operating-now that i look at it more, the corrosion seems to be at an angle, following the fuel level when sitting.

now, the only thing i didnt do was keep track of which pump was in which location, but i am guessing the pump with the corrosion was in the bottom location as i think it would be the only one that could actually have gas sit in it over time while the engine is not in use as fuel could drain out of the higher two pumps to the bottom pump.

also, i have only changed one fuel pump diaphram before, and it seemed to be tighter than the ones i replaced. i tried to show some how loose these were, but dont know if it is apparent from the pictures.

so, from this i would gather two things. first, there is something other than gas in the fuel which is leading to the corrosion seen in one of the fuel pumps, this could potentially crate issues with engine operation. secondly, if these diaphrams were stretched, it would create a fuel starvation issue at higher rpms...this one i am less sure of.

fuel is being replaced tomorrow, as well as the oil. ill rinse the tank with a few gallons just to make sure, drain it again and then fill it and tank it out for a spin.
hope this helps someone.

-Richard

first picture is the first pump, with corrosion.
second is a close up of the diaphrams.
third is a close up of the corrosion
4,5 are the next two pumps, one of which has some slight corrosion as well.

 

[Fishin with buds]

UPDATE***'94 Yamaha 225TXRS Dies once running/fluctuates RPMS's

UPDATE***'94 Yamaha 225TXRS Dies once running/fluctuates RPMS's

well....its a partial success...

so new fuel pumps, gas and filters, new fuel line and cleaning the carbs out got me a better running engine, did not fluctuate rpm's at speed, ran great, no quitting.

BUT!!!! i turned it on/off/on/off tonight...i was hoop netting, so mainly running low idle, setting traps, waiting 10-15 minutes with the engine off, only nav lights and VHF on...went to restart after the third or fourth time and it did the same crank once and sputter enough to disengage the starter, then no pops on the next crank, then after that just cranking a dead engine....

again, tilted it, waited...cranked it again, little pop...nothing after that. ran out of juice, vessel assist, gave us the booster pack, cranked on that, some pops but not much. hooked up his diesel jumpers to us...NOTHING when this happened, like worse than the jumper pack. so then jumped the booster pack directly to the starter and pumped the gas ball a little, on the throttle and it finally took and started up. LOTS of smoke. quickly burned off though. so after this i look and the batteries were new in '04 and '05. so they are probably due. and just a note, they were both charged fully over the past 72 hours.

but still, i feel like i cranked it for long enough that it should have caught before it ran out of juice and was flooded or something. if so, how can i test for this/prevent it and what should i do if it happens?



SUMMARY:

mid rpms fluctuation: solved by new fuel pump, new fuel, cleaning carb

die's at idle: solved with new fuel, pumps, cleaning carb.

difficulty restarting: still exists. guessing because of low battery charge and flooding...but why???


thanks for any and all.

 

[brownies]

Re: '94 Yamaha 225TXRS Dies once running/fluctuates RPMS's

Carb / Fuel problems can ruin a set of spark plugs FAST. I've never had much agreement on plugs becoming fuel fouled on a two stroke, but, when I was having carb troubles, the only thing I could figure out was FUEL FOULED SPARK PLUGS.
Boat would run out great and then just one day get to the lake and it would either NOT start, or, start a few times and then no more.
While sitting in the water, I'd remove plugs, they would look fine, Install a new set that I kept in the boat. It'd fire right up and run GOOD for another week.
The carb/fuel problems that were causing the plugs to go bad were not due to dirty carbs or bad fuel pump diaphrams. I know this because I re-built my fuel pumps and I had my carbs off at least three times. Took em apart, cleaned with spray carb cleaner, blew em out with air, and re-assembled. Not once did I find anything blocked or gummy.
The cure: I removed the carbs, took them apart, soaked in carb cleaner, and installed new carb kits/gaskets. and bought new fuel pump assemblies.
No more gas fouled plugs.
I've still not had anybody agree with a plug being gas fouled, but, I have had it happen to vehicles (junkers and race engines). Once a plug is gas fouled, it may still look fine, but, I've never had a set that would ever perform correctly again.

Just an idea and I may not be the person to listen to. If mine was running right, I'd not be here....I'd be at the lake. lol.
Rodbolt won't even offer up a suggestion for me, however, I think I can hear him laughing at me.

 

[rodbolt]

Re: '94 Yamaha 225TXRS Dies once running/fluctuates RPMS's

no laughter, just amazement. I am amazed you waited so long to simply fix the thing.
but yes gasoline can and will foul a plug.
but if it is you have to find out why.
a failing stator can and has fed the CDI a lower voltage so the CDI will feed the ign coil primary circuit a lower voltage.
soon its simply not enough to arc the .039" electrode gap.
however its all simple to actually test.

 

[Ray Neudecker]

Re: '94 Yamaha 225TXRS Dies once running/fluctuates RPMS's

Note that a battery which does not spin fast enough will not fire the engine and will gas foul plugs.