f225 fuel starvation

[rmf1460793]

I have twin 2004 f225 engines.
the port engine occasionally at low speeds will sputter to a stop.
a few squeezes of the primer and it starts right back up.
I have switched the fuel feeds up to the engine and it is only the port
engine that sputters to a stop. when the engine was only a year old
it went to the dealer for a yamaha recall repair for the issue. It might not
happen for 3 months , then It might happen 10 times on one trip. it usually
only happens at rpm less than 1000, once the boat is up on plane it doesnt
happen. I am a do it yourselfer and I dont mind hangings some parts on, but
would appreciate help in getting the right parts.
thanks for any help.

[boats.net]

Could be fuel pump or air leak on fuel filter or hoses.

[rodbolt17]

ok, lets review HOW the feed pump system works on F200/F225.
at speeds below approximatly 1200 RPM that pump cycles.
10 sec on 20 off.
any airleaks at the filter or hose connections will allow air at the feed pump intake resulting in a lower level in the VST.

after checking all fuel line connections we will get to the most common cause.

most common cause of your complaint is the check valve between the VST inlet and the feed pump intake.

when the feed pump turns on that check valve is closed.
fuel feeds to the vst,once the needle valve closes in the VST and it cann accept no more fuel the valve opens at 10 PSI and releases exccess fuel back to the feed pump intake.

if the valve leaks it wont maintain that pressure and will allow air into the feed pump intake.
as more and more air gets in the system it cavitates,feeds air/fuel bubbles and the VST runs dry.

simple test,while watching the fuel filter on the engine,squeeze off the line between the valve and the feed pump intake T fitting.
when the feed pump cycles ON you should see the filter cup level drop, it will rise as the pump shuts off.

some folks can actually hear the pumpcycle.

[rmf1460793]

f225 fuel starvation

Rodbolt17,
thank you for the reply and the helpful information.
I just want to clarify,
the VST is also known as the float chamber on parts diagrams,
and the check valve I need to replace is called the relief valve
assembly on yamaha parts diagrams, in my case part number
69J-24460-00-00.
can that valve be cleaned or do I just replace?
thanks in advance for your help
bob

[rodbolt17]

usually by the time I see them the Efuels have destroyed them.
they are rather pricy but can be tested with a mity vac pressure vacum tester.

[rmf1460793]

thank you rodbolt for your help
time to put a new one on.
thanks again
bob

[Pogo1968]

Check valve

Rodbolt,
I have an '04 F225 I'm hoping to buy that acts like a fuel starvation problem at higher (than 2000) RPM. Water separator was full of gunk/water, Engine's water separator had some sludge on the bottom of the cup & Filter dirty (replaced). Also replaced dirty filter at top of VST and cleaned the screen on the bottom of the interior pump which looked fine, but still no power over 2000 RPM with surging still occurring. Tank/lines also drained & cleaned, but I'm planning on running off a test tank today to eliminate the possibility air leaks in the supply as the cause.

I tested my check valve with my mity vac and it leaks down instantly, even in the wrong direction with the slightest (< 5lbs) amount of vacuum. It seems to me that it's bad and could cause the same cavitation in the VST at higher RPM (like I have) in addition to the idle/off idle as described by the original poster. Before I go spend the $100, I'd feel better if you could confirm that check valve leaking could also cause the fuel starvation symptoms I have at high RPM.

Thanks in advance,

Pogo

[rodbolt17]

if its bad its bad, fix it and go to the next problem.
that much gunk could have passed on to the injector filters as well.
a simple fuel rail pressure test will tell a lot.

[Pogo1968]

Thanks. I'm going to check fuel pressure today and possibly swap out the leaking check valve if a buddy has one I can borrow. I'll let you know how it goes.

Pogo