Yamaha 150 OX 66 Fuel Problems

[Captain Steve]

I have a 2004 yamaha 150 OX 66 (SX150TXRC) that is starving for fuel above 4000 - 4500 RPM's. I have replaced the water/fuel operator, and I have replaced the fuel filter, filter housing, and O-Ring, that is mounted under the cowling.

She has been running good until yesterday when crossing a rough bay, and after we started pounding the waves, she started acting as if she was starving for fuel at high RPM's. Fished all day putting and *****ing around, and she was running great again, up until i had to start pounding across the rough bay again to get back in.

Any suggestions?

[rodbolt17]

have you disassembled and replaced the filter in the vapor separator?

[Captain Steve]

have you disassembled and replaced the filter in the vapor separator?

Cleaning/replacing the filter in the VST is where I will start tomorrow morning.

Could it also be that I have crap on my pick-up tube in the main tank? Was going to try disassembling the hose at the tank, and blow thru it. ???

I have also read where I might want to try replacing low pressure pumps if replacing filter in VST tank, and cleaning fuel pick-up tube doesn't sort the problem.

Any other suggestions?

[rodbolt17]

fuel pumps don't last forever, I recommend replacing the lift pumps every 3 years.
VST filters clog, the VST pump is a blow through design so it picks up brush dust in the filters.
each injector has a removable/cleanable filter as well.
typically a restriction at the tank will also result in a flat primer bulb.

[Captain Steve]

Thank you for the advice. The predicament I am in now is I need to run this boat over the next 5 days. There will not be a Yamaha parts house open until after the 1st January.

Is the filter/screen in the VST re-usable? What about any o-rings or seals that I will have to remove? Would they all be re-useable, too?

I will have to replace fuel pumps as soon as the dealership opens and I can get them.

Do you have any precautions or is there anything tricky that I can expect when going to the filter in the VST? It looks like I will have to completely remove the VST to get to the filter on the back side.

Thanks again for your help and advice.

[rodbolt17]

best advice, DO NOT run that motor with a fuel issue.
you WILL get to post about detonation and what it did to a piston.

IF the VST gasket doesn't swell it is reusable.

IF the VST filter is not damaged it can be removed,cleaned and reinstalled.

the VST tank CAN be removed without disconnecting any fuel lines.
drain the VST.
loosen slightly ALL the tank cover screws you can access without removing the 3 vst mounting bolts.
then remove the vst mounting bolts.

loosen the last two screws.
remove all screws and drop the tank away.

the pump filter rotates to release the catch.
takes about 45 min unless I am aggrevated or in a hurry.

[Captain Steve]

VST Filter

Thanks very much for the advice/information Rodbolt!

Christmas morning I removed the VST filter just as you suggested, and it was some kind of dirty. I cleaned her out really good, and was able to re-use the filter and the tank seal. She runs like new again!

As soon as the local Yamaha dealer opens, I will replace or re-build the low pressure pumps, as well as replace the VST filter and seal.

Thanks so much again for the advice & information!

[rodbolt17]

if its running well I would leave the VST alone till next time. the pumps are simply maint.
that gasket is about 25 bucks,the filter like 66 bucks.
you may wish to pull the injectors,use a pocket knife pop out each injector basket and spray them out well.
be careful as yamaha does not offer replacements.
mercruiser did for the 97-2001 MPI 7.4L.
same filter.
insert the blade just below the basket rim and just above the injector mouth.

like I say, its a blow through pump.
means the pump body and the pump motor are inline,gaasoline flows over the armeture,over the commutator and brush assy and out the pump outlet.

first one I cut open scared me .

but as the brush's wear the dust goes out with the gasoline only to be picked up by various filters.