Starting issue

[zachery0603]

My grandpa has a Yamaha 25hp I believe it is a two stroke not sure. But the issue I/we have is it will turn over all day but won't fire. I have checked all of the obvious, spark plug and such, fuel. My grandpa was told something about a fuse somewhere on the motor that could be bad I can't find one any ideas.

[TownsendsFJR1300]

Is there a large, flattish fan belt atop the engine and a dip stick(like the car to check the oil), if so its a four stroke engine.

If not, its a TWO stroke engine (probably is). Is there a separate oil tank atop the engine? That would confirm its a 2 stroke.

Point being, if it is a 2 stroke, you need to mix the correct amount of TWO STROKE OIL with the FUEL or you'll burn up the engine (it lubricates the engine)

Did you hook up the spark plugs to the caps, ground (hold) the base of the plugs to the head and while cranking, look for a spark at the spark plug? Without spark, it won't run.

If you have a digital camera, can you snap a picture of the engine (under the cowl) and post it here? It'd help with diagnoses...

There should be a plate on the side of the bracket that bolts to the rear of the boat with some #'s on it. If its there, that's your model and year (really important). If its there, again, please post it...

I'd figure out if it's a two stroke or four stroke BEFORE cranking it anymore as you can damage the engine.


BTW, how old are you?

[zachery0603]

I will figure out today if it's two stroke or four. Yes I have done the spark test and yes it has spark at the spark plug. I am 30 years old btw. I do know this about the motor it mixes the oil and gas it's self you do not pre mix the motor is on a pontoon boat.

[rodbolt17]

in all your years of wisdom, why not simply post a model number?
my daughter will be 29 in june.

I was a tech BEFORE long BEFORE she was born.

[TownsendsFJR1300]

I will figure out today if it's two stroke or four. Yes I have done the spark test and yes it has spark at the spark plug. I am 30 years old btw. I do know this about the motor it mixes the oil and gas it's self you do not pre mix the motor is on a pontoon boat.

Ok, if it pre-mixes oil and fuel its a TWO Stroke..

Has the engine been sitting for awhile? Carbs like to varnish / gunk up over time, (especially the smaller engines with smaler jet orifices).

If you have spark, time to start looking at the carbs.

There should be a drain screw on the bowl of each carb. Can you pull one at a time and prime the primer bulb. Try to catch what comes out with a CLEAN tuna fish can (or similar). Should be clean.

Are you getting any fuel to the spark plugs (are they wet) after you choke the engine and crank it?

[rodbolt17]

over the years there has been a 2 cyl four stroke 25, a single carb two stroke two cyl, a two carb two cyl two stroke and a 3 cyl two stroke.
some of the 2 carb and 3 cyl two strokes also had oil injection.

see why a model number MAY help?

[zachery0603]

I will get a model number today. I will try the carb trick and see if it is clean or gunky. Thanks for the help I will get the model number and post it later today.

[zachery0603]

Motor

Ok so I apologize I have spent the past couple hours with the motor and my grandpa was incorrect it is a 50hp model number is 50TLRZ the numbers below that are 6H5 L 447876 S. I did all the suggested above and everything seems to be fine I have spark on every cylinder at the spark plug and fuel is making it to the cylinder and fuel is fine as well. We live in Indiana this boat us kept in a climate control shop over the course of winter and winterized every year before stored. This is the first year we have had any issues. Hopefully somebody has a suggestion. Thanks in advanced.

[TownsendsFJR1300]

Well, if you have spark and you have fuel, you need confirm you have compression.

Please check compression in each cylinder, cranking with the plugs out (connected and grounded) so the engine spins the fastest for the highest #. Hold the throttle wide open when cranking.

If you don't have a compression gauge, most auto parts stores have loaners you can borrow. All pressures should be within 10% of each other.

Also, does that plate with the model #, give you a build date? And is it a 2 or 3 cylinder engine?


*Make sure you have a fully charged battery when cranking, trying to start, etc..

[zachery0603]

It was built in 2001 and it is a three cylinder. I don't believe it is compression I will check it but don't think this is an issue. My grandpa told me a couple years ago this happened at he took it to a boat shop and it was a fuse under the cowl around the shifter cable could this be true?

[TownsendsFJR1300]

Part #10?? Its on the starboard side where the cables would be...

2001 50TLRZ Yamaha Outboard ELECTRICAL 2 FOR 40TR 50TR Diagram and Parts

[99yam40]

It was built in 2001 and it is a three cylinder. I don't believe it is compression I will check it but don't think this is an issue. My grandpa told me a couple years ago this happened at he took it to a boat shop and it was a fuse under the cowl around the shifter cable could this be true?

A motor needs good compression, good spark at the correct time(timing) and the proper fuel to air ratio for it to fire cylinders properly.
Test what you can and then work at the things you cannot.
Too much or too little fuel will cause problems