I have a 2013 Yamaha 150 four stroke and have changed the fuel filter and water separator and still it�s like I am running out of gas when I throttle up. Also the fuel filter cup drops down on a hard acceleration. The engine won�t get more than 3300 rpm unless I let off the throttle and slam it down. The boat has only 50 hours on it. I�m at a loss here and very frustrated. Any help is much appreciated

Trust me on this one Take it to the shop and let them check it. I tried all above changed gas to fresh, I always run ring free in the engine. Turned out it was not good. If I had took it in when it first started may be I could have saved the engine but now $$$$$$$$$$$$$$$$$$$$$$$$$$$.

I am a do it yourself er but there comes a time when the computer can tell you things you can not see without it. A Shop bill can sometimes be cheap......

This is
This is good advice

The motor I speak of is a 2010 250 SHO. I bought the boat with a new power head thinking all is well.The motor had 75 hours when I bought it. It started just like yours 3300 rpm's at start up and hard to get on plane
When I removed all the fuel the next trip all was good, up on plane and ran like it should. We made our 1st run on the 2 nd take of 3300 is all it would do. 3rd take off 3300 all it would do. As we started back to the ramp it kept loosing rpm's down to 23 then 19 then 12 at last all it would do was idle. The motor never ran ruff is was smooth all the way down. About 3/4 of a mile from the boat ramp it made a squealing sound and started running ruff. We shut it down and trolling motored the rest of the way in.
When I took it in to be checked it was too late. The computer showed the oil pressure was low and the protects on the engine were letting it run in the protected mode at low rpm's. Taking it in may have saved a lot of $$$$$$$$$$$$$$$ but who knows for sure. The low oil pressure let the crankshaft spin and locking up the engine requiring a new power head. With one failure already does it make since to fix this engine again when the first on did not hold up. The power head is 3 years old with 100 hours on it. Yes Yamaha knows the engines have had problems and working on them all the time. Yes I knew the engine had a new power head on it but thought the bugs were fixed. There is no warranty on the engine and insurance will not cover an issue like this. Making a request to Yamaha for some out of warranty help but that is a shot in the dark.

Good luck finding the cause of your loss of rpm's but take it and let a trained tech run it on the computer to find the exact cause. Could be something simple but on the other hand don't want to see someone else go through what I did.
dobbin

If I may add to this and share some of my recent issues. I too ran into the same similar issue and after the same attempts as you mentioned and no fixing the issues. I ended up studying how a four stroke fuel system operates.

The fuel system on ALL FOUR STROKES regardless of their brand all operate the same across the board. Gasoline is sucked into the engine by a LOW PRESSURE Fuel Pump (LPFP). The LPFP has a small filter usually right in front of it to filter out [censored] that you don�t want going into your fuel system. This filter should be replaced based on how much you use your boat.

The LPFP then pumps fuel into a High Pressure Fuel Pump (HPFP), this is the pump that feeds the fuel injectors. This HPFP has internal fuel screens that get clogged and when your idling, no big deal, but when you need more gas, they limit the amount of fuel going to the injectors. So, you probably have a HPFP clogged fuel screen.

Having done everything you did, the only last variable was my HPFP. Since my OB was an 06� and how much the techs charge in my area and the Local techs charge $125/hr and the last time I was in for the same issue and it came out just shy of $1k and it worked for about 6mos, just enough that it passed their warranty period. I figure I had nothing to lose but do it myself. Depending on how mechanical you are, you can do this too. For less than $450 I purchased a brand new HPFP, I didn�t want to mess with opening it up, plus it was like 13yrs old anyway. I put the whole new pump in and I fixed my whole fuel issue and the motor is running perfectly now.

Now, it wasn�t simple, I took my time an it took some studying on all the hoses attached and take lots of pictures of before you start taking hoes off so it�s a lot easier to put back on - but it worked.

Good Luck.

Thank you everyone for your help. Yes I am very mechanically inclined. I�ve been in the auto repair field my whole life. From what I�ve seen yesterday the fuel pump filter bowl empties on a hard acceleration I am going to change out my primer bulb this morning and then go after the vst pump which I believe is the hpfp. I bought the boat with 23 hours and put 25 on it since. I�ve had boats my whole adult life this is my 5th and never have seen or had this issue. If I can�t get this going after today I am going to take it in.

Also I have noticed a lot of air in the primer bulb. But I�m telling you at idle it fires right up and has all the throttle I want. But it still on a hard acceleration looses about half the rest out of fuel in the filter cup/housing.

Karl, yes, you are correct, it is called the VST, I just said LPFP & HPFP to make the point easier to understand. You might want to check fuel line coming in from the tank. I also had to change out my primer once, went to squeeze the bulb and it just like crumbled.

Good luck, I�ll be following your updates.

Well took 3 fuel samples no water separation out of the separator the bulb or the vst. Changed the primer bulb and found I have good hot spark to the coils and plugs. Tomorrow I am going to bring my fuel pressure gauge home and take a fuel pressure reading. I also am going to siphon the fuel and whatever else I can get through the sending unit area on the fuel tank. I will pull the injectors and self clean them on my own due to there is a 3 week turn around here in Texas. I am from Illinois and have had fuel sit for up to 6 months in my bass boat there without stabil and never have had this issue. I�ve had mercury mariner and Honda outboard never an issue EVER. These Yamahas are garbage. I will never purchase one again.

Hello again. Took apart the vst and pulled the filter off. Has some sediment on it but from my stand point it doesn�t look like the culprit. My wife is going to pick up a new vst filter and some in line filter on top of the vst tank assembly with new gaskets tomorrow. Taking this thing apart was a breeze. Maybe 30 mins tops. I talked to a reapair place today and was told taking a fuel pressure reading was a waste of time so I took his advice. Tomorrow it will go back together and the muffs will go on in the driveway to see if it still stumbles. If so I�ll break down the injectors and clean them next.

Ok here is my last post to this thread. After replacing fuel filter , water separator,vst filter there was no change at all just a lot of aggravation. But thank you gulf coast complete marine for having everything I needed in stock and ready for my wife to pick up for me so I could do my repairs after working hours. Also replaced the spark plugs. Took out the fuel injectors and brought them to aces marine who cleaned them by machine with a really cool print out. Just installed them an hour ago and now the boat iengjne is smooth as glass while running and no hesitations. I spent a total of maybe 4 hours traveling for parts plus phone time and repair time. Spend a mere 360.00 in parts and injection cleaning. The result will be priceless when I get back out with my wife and kids cruising and tubing and lots of happy smiles while enjoying the outdoors. Also may I mention the time I get to get out and hit those big bulk reds at the jetty and the trout at the reefs. Not to mention the snapper at the first rig. Everyone thank you for your advice !