runs perfect on trailer no power in water HELP

[seaox250]

hello all,

new to the forum, thank you to anyone who can help in advance...

i have a 94 yamaha 250 2 stroke i recently purchased used on craigslist. it has 110-120 psi for compresion on all 6 cylinders, and ran on a stand before i bought it so i thought i was in the clear, well i was wrong

i put it on my boat and have had no luck getting it to run right, and i have replaced a list of parts chasing this problem.

on the trailer it runs great, revs propperly and is very responsive (even in gear) but as soon as you put it in the water and try to get speed it just doesnt go, i cant get past 7mph

all 6 carbs are clean
new cdi box
new plugs
all 6 coils show a signal when running (on a test light)
the entire fuel system on the boat is all new (tank, lines, filters)

it smells rich to me but seems to be a pretty consistant miss like it is in some kind of limp mode, and has a low rev limit for some reason

i am at a loss someone please help!!!!

[DennisG01]

It sounds like you may have a traditional, rubber-hubbed prop. Take a look at the prop and look for a pressed in, rubber hub between the inner "spline" area and the outer part (where the blades attach). When the rubber gets old, it's kinda like an old clutch in a car... with light power being applied, it'll somewhat work. But with increased throttle (load), the rubber will slip -- the RPM's will jump up, but the boat won't go. Most any marina can send it out to get it re-hubbed.

[seaox250]

i just put a new prop and that inner piece as well when i put the motor on the boat. and just to clarify the rpm doesnt go up under load... it is a project boat and i dont currently have a tach wired but im definetly not getting max rpm like i do in nuetral or on the trailer

[DennisG01]

Shoot. I was hoping for the "easy" fix for you! This is going over my head, now. But I would recommend posting the entire model number. If you've done any reading of other posts on this site, you know it's important for people to know exactly what model you have. It becomes almost like a broken record to ask for the model number, but it is needed.

[seaox250]

yea lol we are way beyond the easy fix option with this thing lol

it is a 94 yamaha 250 txrs 61a

[99yam40]

What RPM does it get up to?
Do you know if the alarm buzzer works and does the tach show any indicators of what is going on?

[seaox250]

the tach is not yet wired as it is a project boat that i have become much deeper into than expected... big surprise right? so anyway i stopped putting money anywhere else with the project until the engine was running right so no working gages

if i had to guess i would say its somewhere around 2-3000 rpm

but if its on the trailer and in gear it will rev to the heavens

it will also rev proper in nuetral in the water just once you put it in gear and hit it, i only get 7 mph and the rpm get to a certain point (2-3000rpm) and seems almost like it hits a rev limiter

the engine alarm is there and does sometimes make a slitght whistle but is not always on even though the problem never goes away

[ausnoelm]

Revving in neutral is useless, it proves nothing at all, not too sure why you replaced all those parts, but, do you at least have a genuine manual for your model? How did you "clean" the carbs?

[DennisG01]

"hitting the rev limiter"... someone correct e if I'm wrong, but in that case the rev's would sort of "bounce" at the limited RPM?

Could a throttle setting/linkage on the motor be mis-adjusted?

[ausnoelm]

"could" be lots of things, so far we know nothing except it revs in neutral.

[zenoahphobic]

Revving in neutral is useless, it proves nothing at all, not too sure why you replaced all those parts, but, do you at least have a genuine manual for your model? How did you "clean" the carbs?

It atleast proves engine runs, and reasonably balanced so fault probably confined to electronics/fuel system or throttle link not going full motion.

Worth a quick check that throttles are advancing fully, a simple hood off engine not running lever fully forward visual check.

[rodbolt17]

revving ANY outboard on a flusher is a teat on a boar hog.
did I mention teats on a boar hog?

now a MODEL number of WHAT motor we are discussing is a teat on a momma black lab.

its all about the teats .

[TownsendsFJR1300]

revving ANY outboard on a flusher is a teat on a boar hog.
did I mention teats on a boar hog?

now a MODEL number of WHAT motor we are discussing is a teat on a momma black lab.

its all about the teats .

OMG, LOL..........Its not even the weekend....

[seaox250]

sorry if i am not being specific enough... i thought the trxs or whatever i posted earlier was the "model number" i am new to boating and replaced all those parts because they are the ones the local mechanic told me to. sorry my knowledge does not match yours in this matter but that is why i reached out for help... because i need some help.

thats being said it is definetly getting full throttle i have checked that

is there a way to attach a video of the boat in the water? to help better show you all the problem i am encountering..

thank you all again for the advice

[seaox250]

also i know we have established reving in neutral shows nothing but what about when in gear on the trailer? it has no problems revving then even in gear only when its in the water