Aggravating 4 month problem on a 25hp -4stroke

[wales381]

I’ve had this outboard since 2010, purchased new and have done all maintenance with no problems till this winter. I run the boat year round and haven’t sat for more than a few weeks. Motor is a F25leha

Motor will idle fine but when giving it throttle, motor would chug and not get on plane. Pump the bulb and get the boat on plane and run fine. Talked to a mechanic and ended up replacing the fuel pump and line with virtually no improvement. Boat would get on plane for a minute then starts chugging and eventually stalls. It will start back up and idle just fine. Took apart the carb, cleaned it, and put it back together and added new plugs.

Took it out ran great for 5 minutes but when coming off plane, motor suddenly died. Tried to start it but gas was pouring out of the carb. Took it apart again cleaned the float put it back together but had the same result. SO, off to first Yamaha certified mechanic who said he cleaned the carb, found some debris and adjusted the stuck float. Also did a compression test which came back good. Cost me a couple hundred bucks. No biggie.

Went to the lake the other day, boat ran great for about 2 miles. Yesterday, drove to a lake for a fishing trip, went to start the motor, nothing. No spark.. nothing. Checked the battery and wiggled the connection and fired right up. Boat got on plane but started slowing and would go fast enough to keep it on plane. Fished one spot started to move to another spot but the motor started to die when on plane. Again it idles great but get the boat up on plane and it slowly starts losing power. No lights or sounds come on, good pee stream, and good air flow. Checked the gas tank and it looks fine, with no debris in the tank or water. I’m stumped…. Any suqqestion’s

[DeltaDawg]

I have a 2001 25hp 4 stroke. I drain the carb after each use through the screw on bottom of bowl into a cutoff plastic cup and pout back into tank. I buy gas from a busy gas station on the hwy not on water, I have the external 10 micron quart size Yami water separating 10 micron fuel filter. I have a Harbor Freight vacume fuel pressure gage to check fuel pump pressure. I have both the Yami shop manual and Clymer manual and I like to read and reference both. Your problem does sound like a fuel starvation problem to me, you wrote they replace the fuel pump, did they replace the inline filter? Can you see pink in the inline filter under the cowling like you got some gas that had stabil in it? The wiggling wires to get it to fire could be a loose bullet connection going into the fuel enhancement (choke) solenoid on top of the carb. I am sure you will get better guidance from, younger, smarter, more experienced gearheads than me, just sharing what is working for me now. Oh, I buy extra in line filters, and a spare new carb and fuel lines to have on my garage shelf from these folks. Good luck.

[Templar33]

Hesitation?

I have a 2003 F25 and after I got it back from the repair shop where they overhauled the carb, I also had a hesitation in it. As I would throttle up it would chug down and sometimes cut off. But, by babying it, I could get it up to full throttle and it would run fine wide open.

I tried some changes- my first change was to move to non-ethanol fuel. My second change was to use Seafoam fuel additive to dissolve any gum in the fuel system from tank to carb.

The seafoam worked wonders. Today my Yammy runs like a top with no hesitation. And I won't go back to ethanol fuels either. I also use Sta-bil fuel stabilizer. It is my opinion the seafoam is what worked the magic on my motor.

I did the cleaning additive first which is 2 ounces of seafoam per gallon of fuel. And after a good cleaning I run regularly 1 ounce of seafoam per gallon for maintenance.

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After re-reading your post, it sounds like you may be getting some small particulate matter into your carb clogging it up. You might consider replacing your fuel line and fuel filter and maybe even your tank if you suspect it too. And you may need to reclean your carb once you have an all new clean fuel delivery system. But once you are certain you are getting clean fuel to your carb, try the seafoam on it and see if it helps. I am loving the results on my yammy! I can hole shot with no hesitation what so ever and run wide open smoothly now.

Good luck and let us know your outcome.

[acehiggy]

Lucas fuel treatment works great also! I use it in everything.

[midgiegualla]

Have you replaced the fuel line from tank to motor(Inc: connectors and bulb primer) ? Maybe borrow one and see if any improvement is noticed.

HERE IS MY STORY :
I had a similar problem a while ago that took me months to find. I could put the boat in for a fish and cruise around for a hour or two without a problem then all of a sudden for no apparent reason it would start starving for fuel. If I kept pumping the bulb it would keep running but if I left it alone it would stop completely . On every trip , once the problem would start it would continue the whole day. Then , next trip the following week , it would run perfectly again for one or two hours and then the problem would start again !!!!
At first this is what I did : CHANGED FUEL FILTERS , DRAINED FUEL TANK AND CLEANED & CLEANED OUT CARBY.
I also checked the fuel line from tank to motor and fuel was flowing through fine (no problem with that I thought) WRONG !!!!!
After doing all these things the same problem persisted , And I had run out of ideas. I GIVE UP !!!
Anyway one day I grabbed a beer and the fuel hose ,sat at the table out the front of my house and as a last resort , Started to pull the fuel connectors apart. ( I knew I wouldn't find anything wrong because I had checked the fuel flow 100 times and it was fine) But you never know !!!
As expected I'm sitting there looking at the disassembled connector and thinking that there is NOTHING wrong with that. So I just continue to enjoy my beer while tapping the connector on the table in disgust . After finishing my beer I decide to put the connector back together.When I look down at the table where I was tapping the connector I saw this very small (1mm) red flake. What the hell is that ?? Where did that come from ??? I look inside the connector but could see nothing else. Could something that small cause a blockage. I didn't think so.
I decided to soak the connector in fuel and tap it on the table a bit harder. *** !! Another red flake !! After a bit more soaking and tapping I had collected at least 6 of these small flakes.
Then grabbing a magnifying glass and having a close look at these things it hits me !! They are FISH SCALES !!! ( "Yakka"scales to be more precise . These are small fish we use over in Aus for bait)

This is what had happened : Over years of fishing some of these scale had worked there way into the connector. I'd say when connecting and disconnecting , if a scale was on the end of the connector there is a fair chance that it could be forced inside when you plug it in , never to see the light of day again.
When the connector was dry of fuel (boat in garage for week) the scales would stick themselves to the inside wall of the connector and make themselves practically invisible and not restrict fuel flow . They would stay there until you took the boat out again. But it would take a good hour or two of the scales soaking in fuel to break loose from the wall and clog up the fuel flow.Once they are loose you have fuel dramas all day !!! You go back home , park the boat in the garage for another week , the fuel in the connector dries up , the scales stick to the side of the inside wall and become invisible and you are back to where you started !!! Once I got rid of the scales I never had another problem.

I know this may not be your problem wales381 but I'd be checking them anyway. Sorry I got carried away with my story but you never know it may help someone else if not you !!

A couple of morals in this story : NEVER ASSUME , START WITH THE SIMPLEST SOLUTION FIRST AND WORK YOUR WAY UP & BEER DOES HELP SOLVE YOUR PROBLEMS !!!!

[wales381]

I actually have replaced the fuel line and bulb leading from the tank into the motor. Haven't replaced the lines inside but that might be worth it. I've taken apart the filter inside that connects to the fuel lines, i'm thinking fuel filter but its too late to remember. I've also been a religious about using Stabil and try to use it every fill up. Also tried Seafoam for a cleaner and followed other instructions on de-carbing the carburetor. Done all that and still no improvement.

Unfortunately, I am not close to a place that sells ethanol free gas as the closest one is about 1.5 hours from the house. Only thing I can think of is a new tank along with the fuel/water separator. That I will add. Right now, I became flustered and decided to let a smaller shop with a certified Yami mechanic look at it since its still under warranty. Once I get it back, i'll be adding a different tank and a water separator.