fuel pump voltage issue 2003 Yamaha f225 txrb

[rae517]

With the key on, lanyard in place voltage reading at fuel pump fuse is .8 volts. New pump (about 2 hrs. running).
I was having a stalling problem, determined the problem was electrical. Last time engine ran, measured 12 volt at pump fuse. Rain ended that session. When I returned boat would not restart and only .8V at pump. Does the same source that provides 12V to the pump also electrify the ignition? Could I have knocked something loose putting the engine box back on?

Read somewhere about a wiring harness issue involving a 3 wire connector at the front of the motor (R/Y, R/Y, R) hard wired around the connector, nothing changed

A 12V jumper to the pump will cause the expected 5 second cycle.

 

[SparkieBoat]

Re: fuel pump voltage issue 2003 Yamaha f225 txrb

I think the ECU controls voltage, but I am not sure it could be a relay. but the ECU still probably controls the relay..see if you can find a wire diagram. if it is not getting fuel it will not crank even if it is firing. welcome to the wonderful world of F Yamaha motors.

 

[rae517]

Re: fuel pump voltage issue 2003 Yamaha f225 txrb

800 hours without a hic-up, now this. my worst fear is that I managed to short out the ECU while poking around. Any way to verify the ECU without replacing it?

 

[99yam40]

Re: fuel pump voltage issue 2003 Yamaha f225 txrb

If only getting .8 v at fuse then follow it back to see where you are loosing it, wiring diagram will help but should be able to do it without maybe

 

[SparkieBoat]

Re: fuel pump voltage issue 2003 Yamaha f225 txrb

my 2003 F115 only has 330 hours and has given me all kinds of trouble, I know others with newer motors and less hours that have had great problems also..800 hours is good.

 

[rae517]

Re: fuel pump voltage issue 2003 Yamaha f225 txrb

I have a Yamaha expert coming by this weekend to help me figure out how I lost voltage to the fuel pump. He believes the original condition - stalling - is due to vapor locking. He asked if the check valve in the breather tube on top of the air intake was clogged? yes. While running did I observe a big air bubble appear in the separator bowl? again, yes. Does the problem only occur at low RPM? yes. Will follow up soon as I learn more

 

[SparkieBoat]

Re: fuel pump voltage issue 2003 Yamaha f225 txrb

a lot of low rpm stalling is also caused by TPS out of adjustment, also caused ECU sending bad voltage to sensors.

 

[99yam40]

Re: fuel pump voltage issue 2003 Yamaha f225 txrb

a lot of low rpm stalling is also caused by TPS out of adjustment, also caused ECU sending bad voltage to sensors.

Maybe the 5 volt reference , but should not effect the 12v in my opinion.
You notice how I cover myself at the last

 

[jeffersondodson561]

Re: fuel pump voltage issue 2003 Yamaha f225 txrb

As with all newer motors start with a load test of the battery. Should be around 1000mca starting battery. Engines suffering from vapor lock are usually caused by excessive fuel vacuum. I would have your mechanic do a fuel vacuum test. Their is a test to see if their is air leaks but I prefer taking the fuel hose off the fuel pickup (tank), crimping it and pulling vacuum around 10-15"hg and see if it holds. The problem with boats is that they pull fuel to the engine. Whereas your car pushes fuel to the engine, fuel pump is in the gas tank. Before replacing any component this test should be performed. No more than 4"hg should be recorded (and 4"hg is high in my oppinion). After that time to go "glory seeking".

http://content.screencast.com/users/jeffersondodson561/folders/Jing/media/4ef257ee-5a67-411e-8679-e79275cecff0/2011-08-25_1112.png

 

[SparkieBoat]

Re: fuel pump voltage issue 2003 Yamaha f225 txrb

I am not sure but I think the ECU controls the relay for the 12v going to the pump, so if the relay is good that would leave the ECU as the problem..I could be wrong. without a wiring diagram..I probably have one, I will look and see. a stuck ISC valve can cause the ECU to over heat and do weird things also..that is a problem I personally had. ok I looked at the wire diagram for my 2003 F115...the high pressure fuel pump has a blue wire that connects to a common ground and a blue/yellow wire that goes to the ECU.....so it looks like you may have a bad ECU..be sure to check your ISC valve..if it is stuck it could be what is/has caused your ECU to freak out/burn up. From what Rod told me most ECU failures are caused by another component, so if you just replace the ECU you could burn the new one up unless you are sure all the other components are in good working order.

 

[rae517]

Re: fuel pump voltage issue 2003 Yamaha f225 txrb

Problem solved! Vapor-lock; clogged breather, The tank fed by the fuel pump (on the engine) overheats at low speed causing the fuel to vaporize; pressure is relieved through the breather (top front of engine, middle hose), the breather joins the crankcase breathers via a (unnecessary) check valve, which is prone to clogging; when this happens the vapors are forced towards the fuel source, puking all of the fuel out of the system and you run out of gas. Squeeze the bulb and you are good to go - for another five minutes. Replace the check valve with a hose barb.

 

[99yam40]

Re: fuel pump voltage issue 2003 Yamaha f225 txrb

glad to hear you found the problem.
Never heard or read about that check valve and problems it can cause.
Thanks for posting what you found
Still I would have replaced with the proper part, Yamaha put it there for some reason.

Could there be some way to cool the VST better to avoid it over heating?

 

[rae517]

Re: fuel pump voltage issue 2003 Yamaha f225 txrb

I agree, all things being equal, you should replace the part with like kind; in this case however I think it is just over-engineered, the breather can only blow, it can not suck, so why the check valve and the issue it can cause?
Since the VST is bolted to the engine block, its cooling is determined by water flow through the block; at low speed the water flow is diminished, hence higher temps. I live way upriver (read no wake zone) so I am forced to do a lot of idling.

 

[99yam40]

Re: fuel pump voltage issue 2003 Yamaha f225 txrb

Maybe something to do with the crankcase vent pulsating since all is tied together, who knows for sure.

I thought I had read about a kit for some motors that bolted to the VST and had water from the indicator routed through it to help keep the VST cool. Could be wrong, but it sounds like a good thing to do