150 ox66 fuel pressure regulator

[Bitsamonkey]

All was well for a while until lately when I noticed some slight rpm fluctuations while cruising. I thought it was the vst screen again, so I took it out and cleaned it and also cleaned the screens in front of the injectors. I reassembled everything and now the engine will not run for more than a few seconds. The electric pump comes on with the key, but only generates about 20 psi. After a few seconds the engine runs out of gas and stalls. I took the vst apart again and removed the pressure regulator and cleaned the screen and regulator. I blew some compressed air through it and it would only hold less than 20 psi, which made sense. Again reassembled everything and no difference. Now I decided to pinch the return fuel line while running and voila! I just want to make sure it really is the regulator before I shell out $190. I guess it beats $800 for a new pump.
By the way, I found that the vst gasket can be reusable if you dry it out real well with a heat gun. It took a while but at $40 I guess it's worth it.
1999 px150tlrx

 

[rodbolt]

Re: 150 ox66 fuel pressure regulator

yep, its the regulator.
if the screen clogs pressure increases not decreases.

 

[Bitsamonkey]

Re: 150 ox66 fuel pressure regulator

I bolted the new regulator on and it's running great.

A couple of side notes:

If you have an efi yamaha and buy a vst gasket, save the old one as it will shrink back to size after all of the solvents have dried out of it. That way you can just rotate them whenever you need to service the vst

I (unknowingly) bought some aftermarket low pressure fuel pumps (mallory) which are total junk unless you open them up and file down the stainless cup between the diaphram and the spring. One of my pumps failed after only a couple of months because the razor sharp edges of the cup cut the diaphram.