VST pressure pump failed

Yamaha 2001 250hp two stroke model turz. Engine was stored 18 months and now the fuel pump as no sound,and no 35lbs of psi at the schrader valve.Got rid of all old gas in main tank, new water/fuel separater,new engine fuel filter. I now have the fuel pump on the table and want to know if I can hook the blue wire terminal on the fuel pump directly to the negative post on a 12v battery, and the red wire terminal directly to the positive post to check it? Prior to pulling the pump I was getting 12v with just key on, blue wire to engine ground and cranking engine I got what looked like was a couple of volts,but I was 8feet away.Didn't check the red terminal to ground. I'm now convinced to get a trusted mechanic to prepare these engines for storage.

Re: VST pressure pump failed

now that its out.
buy a can or two of Yamaha combustion chamber cleaner,or any other equivalant.
fill a small mason jar or other cylindrical container with the cleaner.
place the pump in it overnight.
then use a battery and two jumper leads to toggle the pump manually.
you want to strike the leads not directly attech it.
object here is to break the armeture free not burn out the pump windings.
hook the blue wire to negative,hook one jumper lead to the red wire and strike the other jumper lead against the positive post.
then reverse the leads and strike again.
that pump has no problem with reverse polarity it will just try to run the other way.
and that is how we break them free,if they are gonna.

Re: VST pressure pump failed

`Thanks Rodbolt, and after 15 to 20 attempts ,and reversing the polarity, bingo it started running. Finishing the year,with saying your the greatest ,and your 5 star yamaha mechanic certificate tells it all.

Re: VST pressure pump failed

great.
now just keep it clean, you may wish to clean or replace the injector screens as well.
remove the injectors,carfully clean around the filter area.
use a small knife and work the filter out.
soak the filter in the cleaner and then spray off with carburator cleaner.
or use the filters from a 7.4L mercruiser of about a 1998 vintage.
the 5 star took 20 minutes, my master tech certificate took a few years longer.

Re: VST pressure pump failed

Will check the injectors, but I still have a problem. I can hear the fuel pump now whirl then shut down, and engine will not start. yes,vst is filled up. When I put a little mixed fuel in the plug holes, engine fires right up for 3 or 4 seconds then quits. With key just on, and fuel injector gas feed line off the vst, gas will come out while pump is working,and then quits,and the gas stops. I have a fuel pressure gage ,but I need a go between fitting for the scharder valve, but will get it, so I'm not sure on the 35psi. When I push in the scharder valve I get gas but not much pressure. And can you tell me if the Brass body that the test valve is in ,if I can unscrew it from the vst and replace it, as the valve is leaking and is epoxied to the brass body. It's a flat faced schrader valve and I want to go back to factory.

Re: VST pressure pump failed

As a conclusion to my dilemma all is well. And my mistakes in attempting to solve the problem were.........after getting the fuel pump unstuck and in a hurry to re-assemble I didn't double check the importance of the white plastic washers, the o rings and especially the o ring on the tall post. I think what happened was ,i was getting the fuel pressure back into the vst, when it was supposed to just get a pour back so to speak. As far as replacement on the brass tee that the schrader valve is in for testing the fuel pressure, I found out that it's pressed in, and have to buy the whole upper half to replace it. Also the schrader needle itself has fuel resistance rubber in it. I'll just keep a cap on my leaking one. Thanks Jesus Rodbolt for the guidance, since its Sunday.

Re: VST pressure pump failed

we have a few used VST tanks and assorted parts at the shop if you need one.
no sense in running with a fuel leak.
yes proper reassembly is rather critical, the HPDI motors are even worse.