2004 F225 Stalling at low idle

[takethebait]

I have a Twin F225 TXRC Yamaha outboards. At low idle they sometimes will conk out. I will then pump the ball and fill it with gas and then it start back up. This never happens at cruising speed, just at low idle or *****ing speed. And it is not consistent either..sometimes it happens and sometimes it doesn't. I am not sure what I should look at. Is it the low pressure fuel pump or some other pump or valve. Can any of you experts guide me in the right direction?
BTW, I have replaced all fuel lines, Water Separator filter and the fuel filter inside the engine, and the pump balls.

[rodbolt17]

test the LP pump return check valve.
if it wont hold 10 PSI its failing and that is a symptom.
thats what holds the 10 psi at the pump outlet into the VST.
if it fails fuel starts recirculating from the outlet to the LP pump inlet and eventually the VST goes dry.
that tiny valve is a horse choker to buy.

[takethebait]

test the LP pump return check valve.

Thank you for your reply. i am on the following web site trying to find the part you mentioned above. I cannot find it in any of the diagrams.

Marine Parts Plus Yamaha Outboard 2004 F225TXRC

Could you please point me in the right direction to find that part? Thanks again.

[rodbolt17]

look under fuel injection pump 2, ref 1.
relief valve assy.

[Sparkieboat]

yamaha seems to be in the horse choking business. wont be any horse left in another few years at this rate.

[takethebait]

Relief Valve Assembly

Thanks again for your expert advice. I will order these and replace them and see if that fixes my issue. They are a little pricey...but i guess you gotta pay to play! If I attempt to change this myself, can you tell me is this part difficult to get to? Or should I reach out to a mechanic to get these changed? Thanks again for all your advice.

[99yam40]

test the LP pump return check valve.
if it wont hold 10 PSI its failing and that is a symptom.
thats what holds the 10 psi at the pump outlet into the VST.
if it fails fuel starts recirculating from the outlet to the LP pump inlet and eventually the VST goes dry.
that tiny valve is a horse choker to buy.

He said to test, always best to test to see if that is the problem before buying parts

[Michael j]

Try installing a clear hose at the motor filter to check for air leaking into system.
Also try a vacume gauge to check for fuel restriction (anti-siphon valve ?)
Easy check before you choke the horse.

[rodbolt17]

I will try once again to explain how the low pressure feed pump works on the f200/225.

this lift pumpo feeds the vapor seperator tank which contains the high pressure pump for the fuel rail.
this VST has a needle valve to shut off fuel into it once its full regaurdless of if the low pressure pump is running or not.


at speeds below 1200 RPM the low pressure pump is ON for 10 seconds and OFF for 20 seconds.

the relief valve is simply a recirc/low pressure regulator.

if after say 5 seconds at 650 RPM the VST is full the relief valve opens,opens at 10 PSI or so,and now the vst needle is shut blocking low pressure fuel into the VST.

the relief valve opens and the excess fuel is routed back to the low pressure pump intake.

if there is an air leak on the suction side of the lift pump OR that relief valve is leaking the lift pump becomes air bound and the VST runs out of fuel.

thats why careful testing coupled with an understaning of HOW the fuel system works is imperative.

or you buy a lot of expensive parts and it still quits running.

sometimes.

[takethebait]

Thank you all for the expert advice. It is greatly appreciated.

[snookman]

Takethebait...............did you ever get it fixed? What was the problem?

My motor is doing the exact same thing. It will die out at idle during a restart(only)


It seems as though it runs out of gas while the motor is off after a 30minute + run. I have to pump the primer bulb and then it is fine and will idle fine its just that idle after restart.