twin yamaha f225 2004

[mitch123]

Hi all i have a f225 that is not bleeding the air back to the vst, fuel pressure is reading at 38 psi if i pess the schrader valve air is bled out it runs ok,

on the other motor it is 42psi this is not having the same problem .

Question is does the pressure relief valve bleed off the vapor and if the high pressure pump is a bit worn and not getting enough pressure to cause the pressure to open and bleed off the air in fuel rails.

 

[mitch123]

Re: twin yamaha f225 2004

Thanks for all that replied problem solved ..... oh that's right no one replied

 

[rodbolt]

Re: twin yamaha f225 2004

good

did not see it and with that scanty info could not have helped much.
do you realize there are 2 scrader valves on each engine.
the entire thing about the VST is fuel with NO air,vapor free. hence the term vapor seperator.
its obvious by your rambling things about vapor reliefs,non-existant,and various pressures you really dont have a clue how this system works.

 

[mitch123]

Re: twin yamaha f225 2004

Yep there is 2 schrader valves but one is not pressure one engine had 38 psi the other 42psi.
How much pressure would you get out schrader valve in top of the vst. let me guess none so why worry about it

The engine with 38 psi was keeping vapor in the fuel rail as it was not making enough pressure to open the relief valve and bleed of the vapor.

To get pressure you need flow and a restriction. If the pump has internal leak (worn) it will not create the flow required to make pressure or open the relief valve.

As for not knowing how this poorly designed rubbish works I really don,t give a flying Peking duck what you think. As it is really half assed.Especially on a twin engine install .

Filter the size of a pea on the bottom of the high pressure pump what a joke the last line of defense and it is the size of a pea

Thanks for replying any way as it was not just for you as there are many that can I guess.
As I did not notice this being the rodbolt forum.

 

[99yam40]

Re: twin yamaha f225 2004

Rodbolt is the one with the most experience and knowledge on here that helps people out as far as I know as long as you give the info and he sees the post he will give the info needed.

Did you read #9 on the top thread? http://forums.iboats.com/showthread.php?t=250876

Clogged filters are the normal problem, I have not seen a pump that was worn out to the point it would not get up to pressure. But I do not have that much experience on those motors.
The need to keep the junk out of the motors fuel system is a battle we are all facing and a 10 micron filter /separator is only one thing in the arsenal.
The need to do the preventative maintenance is something that gets more and more important.

 

[rodbolt]

Re: twin yamaha f225 2004

its not a rodbolt forum at all. I actually do this for a living and sometimes either dont see a post or dont have time to log in.
yes that VST filter is a joke but ya outta see the size of the F75 and F90 EFI filters.
the schrader on the tank is for tank venting.
had you run the engine at the problem RPM and load you would have seen your rail pressure drop to less than 20PSI rapidly.
takes about 1.5 hours to do the VST filter and about 2.5 to change the injectors while your there.
each injector has a built in non field servbicable screen.

 

[mitch123]

Re: twin yamaha f225 2004

Thanks for the civil reply , but not every boat is easy to put in the water as we had to wait 24 hours for the next tide with 3 hour drive to get parts.

But it was not even getting 42 psi with key on, with motor not running so pressure relief valve was not opening to bleed off vapor.

Once again thanks for your reply

 

[99yam40]

Re: twin yamaha f225 2004

Sorry, but I still do not see the reason for the pressure relief valve not opening to bleed off vapor causing the pressure from building up to 42. If the pump is pumping liquid then the pressure will build even without dumping the vapor. If it is sucking air I can see why.

 

[rodbolt]

Re: twin yamaha f225 2004

thats cause the pressure regulator has NOTHING do do with vapor seperation.
it has two functions,neither monitored by the ECU.
1 is it maintains a steady 35 PSI rail pressure while running.
2 is when the throttles open rapidly vacum pressure drops on the regulator diaphram temporarily spiking rail pressure by about 5PSI. this acts similar to an accelerator pump.
fuel system inspection and maint is once per year or every 100 hours whichever occurs FIRST.
thats why rail pressure is higher at key on power than when idling by about 5 PSI.

 

[mitch123]

Re: twin yamaha f225 2004

DAMN i replied to this a couple of days ago and it has not appeared dial up internet being in the bush and all

RODBOLT thanks for reply

Question as to how does the vapor that is trapped in the fuel rails get bled off .


Fuel pump was only getting 38 psi with key on engine not running ,it was not achieving the 42psi spike that you indicated .

yam 99
if the pump in poor condition it will not achieve the pressure required to open the relief valve.

 

[mitch123]

Re: twin yamaha f225 2004

DAMN i replied to this a couple of days ago and it has not appeared dial up internet being in the bush and all

RODBOLT thanks for reply

Question as to how does the vapor that is trapped in the fuel rails get bled off .


Fuel pump was only getting 38 psi with key on engine not running ,it was not achieving the 42psi spike that you indicated .

 

[rodbolt]

Re: twin yamaha f225 2004

like I said the VST,VAPOR SEPERATOR TANK, simply supplies the high pressure pump with a VAPOR FREE fuel supply.
its also why most all MPI automobiles have the pump in the tank.
if your getting air in the rail then either the VST level is low OR the filter is restricted causing fuel to boil.