07 Yamaha 150 vmax WOT problems HELP!!

[Trayce7700]

I have a 07 150 vmax that starts flick of the key everytime but when idles it sits there and sneezes, also half the time when I take off it will not reach over 4000rpms Wot, then I shut it off and fish for a little bit start it back up and it runs perfect, some days it does the rpm thing more times than not but always sneezing while at idle.. any ideas? I’m decently mechanically inclined when it comes to vehicles but boats always seem to stump me... any advice would be awesome!
PS. Motor is on a 07 ranger reata 180vs

[yam911]

Outboard models matter. Is this a V150 or a VZ150. Both are Vmax. One has carburetors. One is High Pressure Direct Injection. Big big difference.

[bassinyea]

Check the VST tank and filter under the engine cowl. Also check low pressure fuel pump. This is a common occurrence for the fuel restriction. If it is an injected motor that would be my best guess. If carbureted, sounds like carbs need cleaned or rebuilt if it is sneezing or possibly again lift pump. Check the basics as well to make sure your gas tank is venting correctly and your primer bulb stays tight but doesn't squeeze itself flat.

My neighbor had issues with his VMAX HPDI which was a 2004 model and both times it was that the VST filter had gotten clogged.

[Trayce7700]

It is the carb model

[headhigh]

When you are running along wide open and only getting 4000 rpm's, push the choke in and see if it picks up power. If it does, you need to clean / rebuild the carbs. I had the same issue with an old ProV 150.

[Trayce7700]

I will have to try that when I pull it out for the first time this year, been too cold still so far... as far as the sneezing at idle any ideas? Has brand new spark plugs, ethanol free 91 octane, new fuel/water separator.... I do notice that when I run a lot of marine sea foam in it seems to run a little better but definitely just acting as a bandaid and want it fixed before boating season picks back up this spring

[Charles Prestridge]

Verify fuel pumps are not leaking. Unbolt from engine block, pump bulb and see if fuel leaks from backside of pumps.

[CJ1]

I will have to try that when I pull it out for the first time this year, been too cold still so far... as far as the sneezing at idle any ideas? Has brand new spark plugs, ethanol free 91 octane, new fuel/water separator.... I do notice that when I run a lot of marine sea foam in it seems to run a little better but definitely just acting as a bandaid and want it fixed before boating season picks back up this spring

The sneezing is the pilots plugged in one or more of the carbs. We picked up our x19 cheap because of the way it ran. Cleaned the carbs and it ran great. One of the best running engines I have owned. Clean them yourself or find someone that knows how to do it and show you. Check your fuel pumps, lines, primer bulb and all the connections. Sync the carbs and adjust the oil pump and you should be good to go. Cj

[cwilt]

The sneezing you are referring to is sometimes referred to as a "lean sneeze". An air/fuel jet/s might be partially clogged or varnished over causing a lean air/fuel mixture. Running a lean carb causes the cylinder to run hotter than normal, causing other issues. Fuel is not just for combustion but also lubricates and cools cylinders..just to keep it simple.

[bassinman215]

Some good advice here. The sneeze at idle is lean - so you'll need to clean the carbs or risk failure. rich fouls plugs. lean blows motors.

Check the pumps, its simple enough. Report back with what you find.

Don't forget the anti siphon valve on the pump if you can't trouble shoot. I had this fail on my Stratos, and it caused the motor to get on plane, hit about 5000 rpm, and lose speed slowly.