twillis: FYI on a couple things I learned the first few times working on the VST

When you remove the top of the VST tank (phillips screws) there is a thin o-ring around the edge of it for sealing the top to the tank. It will expand the instant it moves :(

To get away form buying a new one (merc is also very proud of them $50 for the one oring and $100 for the "kit") Use a sharp razor blade and cut the o ring. Re wrap it around the grove, and cut the extra off. Use super glue to re connect the ends back together. (dont glue your fingers together......) This is what I did and has been working great. I have removed the top of the VST 5-6 times and reused the same oring this way.

When re tightening the phillips screws, make sure the top is sealing level. Dont tighten one screw and move onto the next. Go back and forth accros the top tighteneing little by little. Merc has procedure I just dont have it on me right now and this is the best way I can explain it.

Once you got it tight, start engine with hatch open and make sure it isn't leaking gas. If it is make sure you didnt "roll" the oring, and start all over tightening the screws.

Also clean the pick up screen (green screen on bottom of pump) on the electric fuel pump since you have it out. Its a good Preventive Maintenance mesure

The other way to save the o ring without cutting it is to fit the o ring in the back grooves of the tank then tighten down the back screws first. You can then push the o ring in with a flat screw driver into the groove it is supposed to be in as you tighten down the screws one at a time towards the front of the tank. I learned this the $100 way when I had to buy the whole O ring set from the dealer and then un-did the tank a second time to have the brand new gasket swell out and not fit back in.

I took both the vent lines off and the plug off the top of the vst tank and gas anywhere to bed found. I checked the water coming out the exhaust and no sign of gas! The yellow line had a very small amount of gas in it just under the intake by the breather. Emptied that and ran it for 5-10 minutes and no gas.
could it be something had the needle and seat stuck open and maybe passed thru?

Correction ......No gas anywhere to be found. From vent lines or plug. Sorry for the typo..

It sure could be, but I would probably think about changing the diaphram. The fuel in the yellow line could be from the bad manual pump that was replaced because that line should T off to that pump also. But I'm guessing it is from the VST because the vacuum should have pulled that gas in and burned it off. I guess you could change oil and run the boat for 10-15 minutes and keep checking for fuel smell and gas in the line. If you ran it with the plug out, it may not suck fuel into the vacuum line through the diaphram because it can just suck the air through the open plug. I hope that makes sense!

it was a very small amount of fuel in the yellow line and yes there is a tee in the line from the manual pump, the first thing i did was started it up with a scanner hooked up. everything looked fine. then we shut it off. pulled the black hose from the vent on the vst, no gas, then pulled the yellow hose on the vst, no gas, the we started it back up again and pulled the plug on the top of the vst, no gas, put everything back again and started it up and checked the water coming out the exhaust.
there was no smell of gas anywhere. the oil is not runny and does not appear to have gas in it. if it does it a very small amount it is not reading way over full. i will change the oil regardless..i was going to pull the top of the vst off and see how the screen and needle and seat and diaphram look..

yes it does make sense... thanks for all your input.

look there for fuel

jwp. thanks for the pics i will check there also.
i have a pic of my vst pump but cant attach it on here for some reason.
my pump has a side vent with a black hose that goes down on the back side. and the yellow hose that comes out of the top of the vst pump and goes to the front by the air breather.

if its the same hose as im thinking on mine its a black hose comes off the side of my vst and is labeled vent. there is no gas there either..