Fuel starvation yamaha f225

[fairdeal]

would it be better to just vent it without the check valve?

I would do without any valve,
just route the end of a hose outside the cowling - prob. by removing the plug on the side with no tilt switch
to avoid any possibility of fumes inside the cowling

[marchmadness]

A I found a rubber plug below the vst in the cowling I put it there so fair deal you think it’s better with out restrictions . This is a heat issue only. I know rod bolt says it’s a leak or bad fuel lines I’m just not finding either

[fairdeal]

A I found a rubber plug below the vst in the cowling I put it there so fair deal you think it’s better with out restrictions .

that should be fine.
Fairly sure I've seen old models where the VST vent is nothing more than a hose out the bottom of the cowl.
Later "enhancements" may be only for "air pollution control"

[marchmadness]

I took fairdeals advice and removed the check valve . I ran a tube from the vst out the bottom. I ran it all over today stopping and starting without issue. Things that I noticied was the motor seemed to fire up better, I don't know how to explain it. After starting there was a slight fuel smell. I didn't have and fuel leaking out. Now in the past I thought I was passed this issue so I'm not getting overly confident. The people here are always willing to listen and help and its really great. I hope my issue can help others with there's . I am going to end this thread that I started. I hope not to restart it again!!!

[rodbolt17]

now your putting words out that I never said.
if you ran the VST vent tube outside the airbox then your diagnoisis was wrong to start with. if the motor starts and runs better with the vent hose outside it is not and cannot be a fuel starvation. an overrich A/F mix in the airbox at hot restart but not starvation.
an easier way to find it would have been to simply open the shutters using the free button on the control box. that would have allowed more air.

[marchmadness]

I wasn't trying to be insulting I was just stating what was said before about my fuel issue and the advice given was to help me with the problem described .I'm just a guy trying to fix his motor .

[pstephens46]

Will there be an issue with the direct venting? As far as coming off plane. Some motors get fairly buried with water as the boat settles. Can water run back up that hose???

[marchmadness]

I think it vents out but I’m not sure if it takes air in .

[marchmadness]

Ok its been about two weeks since I posted my last update. I direct vented my port motor and about my second time out the motor died!!!! . Now your thinking what? Oh no it was the starboard motor this time, this motor never a problem .. So I went in and replaced the pressure release valve and direct vented the vst. I have been out several times and I haven't had any more problems. What I am looking for is there any reason not to keep the motors direct vented. I know in 2005 Yamaha added a second vent to the vst system . I guess pressure was an issue. Are there any other options.

[rodbolt17]

ok
I will try one more time.
the vent is simply the vent. as fuel level in the VST rises and falls it simply has to vent or you could not fill an empty VST.
The EPA said you cannot vent the VST to the atmosphere.
later models used a carbon canister to trap vapors and a vapor shut off valve to aid in re-introducing vapors to the air box at hot restarts.

now the relief valve between the VST inlet and the lift pump intake is simply to prevent the lift pump from running in a constant stalled state.
it can supply way more fuel than the motor could physically use.
however any valve or other air leaks at the lift pump intake can allow air in the lift pump and allow the VST level to get low enough that at throttle up it stalls. not enough gas in the VST for throttle up.
remember when you rack the throttle the pressure regulator is going to add about 5PSI more on the rail and the ECU is going to just about double injector on time to compensate for the massive amount of air you just let in.
even the old 12hp motor in the wright flyer used this principle only it simply dripped fuel on a plate heated by the ex to aid in vaporizing fuel.

this is where the tool twixt the ear bobs comes in handy.
you look at the system.
you look at the symptoms.
you make a decision based on a logical thought process.
in this case you stated you can manually fill the VST(primer bulb) and it works as designed.
means the VST wont stay full on it's own.
means the VST is ok.
means the issue is between the liquid in the tank and the VST inlet.
quick way to test the valve????\
simply start the engine when you think it will fail.
let it idle while using pliers to pinch off the hose between the VST inlet and the pump intake.
after a few minutes take off.
if that cures it most likely the valve is the issue.
if it does not hunt for an airleak in the delivery system.

[marchmadness]

Question could pressure build up in the vst caused by the vent not venting cause the vst to run dry? I replaced the relief valve only because I had it already and figured it was original and couldn’t hurt

[marchmadness]

Ok im back again with the same old problem . Same problem motor died again. I had it direct vented still and all seemed good . Ran it got it hot sat for a while started up and it dies again. Now this hasn't happened in the last several trips. Did the usual squeezed the ball and it ran . guess im back looking for an air leak I can't find .

[rodbolt17]

now lets do some critical thunking .
if it was not venting and you tried to fill the VST manually how much fuel could you compress into the VST?

when the VST is empty and you start priming it manually you can hear the vent groaning.

if you will notice, there is an arrow on the vent valve.
it flows one way or you would not neeed an arrow.

if the VST is full then as fuel is being used a slight vacuum MAY form as the level drops just before the needle opens to allow more fuel.

that lift pump can make about 60 psi if needed, way more than you will ever get with a primer bulb.

[marchmadness]

If the tank isn’t venting then you wouldn’t be able to fill . When I squeeze the ball it goes hard. There is no arrow on the vent so I guess it goes both ways. But why does this only happen when hot restart. So the lift should fill the vst instantly.

[marchmadness]

I did replace the pressure relief valve last year and checked it this year it seemed to open at around 10