1989 Pro V 150 Outboard

[dirte212]

When the motor is out of the water it rev's up just fine to 4500 - 6000 RPMs. When it is in the water it *****s in forward and reverse just fine. However, when I push the gas petal down it starts to rev up and then just sputters along with no power at all. The odometer says it is topping out at 1500 RPMs. It will do this with the pedal all the way to the floor and doesn't die or anything just sputters along.

I have looked at the fuel pumps, they are fine. I have replaced the external fuel line connector so the fit is perfect. The carboratuers have been taken apart and cleaned out. There is no obvious blockage in any of the jets or main nozzles. The fuel line throughout the motor looks and feels fine and it has good flow because a hose accidently popped off one of the fuel pumps and fuel was flowing well through it.

Someone told me it could be the compression and so I tested every cylinder and the gauge measured the pressure to 108-110 (psi?) on every single one.

Honestly at a loss here, everyone says it is the carboratuers but like I said no indication any thing is wrong with them when they are taken apart all passages are clear to the naked eye.

[Sequoiha]

couple of things come to mind, out of the water the engine does not require engine timing to rev up, check the timing lever on the starboard side of the engine and make sure it is traveling forward when you accelerate, also does you warning horn work at all, check it, it would also be in rpm reduction and with a non working warning horn you dont know it.

[dirte212]

Warning horn works. Timing lever moves forward. Tested spark plugs all for spark. Arg!

[99yam40]

check timing with a timing light to make sure it is in spec.

Test all you can and then clean carbs better if every thing tests in spec

Compression, spark, timing, fuel pressure/vacuum

[jb123]

i still own a 89 pro 150 and have had to do the carbs up to 3 times to get them right, a pro will go straight to THE CARB and THE JET... ive watched !

[rodbolt17]

occasionally the fitting on the engine cowl fails.
check it carefully as the oring in it was not ethanol resiatant.
not the line quick connect but the engine side of it.
typically I remove it and bypass it with a hose mender.
why a 150 needs a quick connect beats me.

[dirte212]

What should the compression psi be? I read every cylinder and it fell between 108 psi - 110 psi.

How can you check fuel pressure/vacuum?

If the engine cowl and fuel pressure/vacuum are an issue why would it rev up to 4500 rpms out of the water?

[99yam40]

Motor does not need as much fuel when it is not loaded up to turn the RPMs