Fuel starvation yamaha f225

[marchmadness]

I am still searching for a reason for the lift pump not cycling at idle believing this is my issue. These motors are equipped with fuel pump drivers, I guess a relay. They are con*****ed by the information given from the ecu. . I just don't want to start throwing parts at this because they are really expensive$$$$ .

[99yam40]

I do not follow your thoughts that the lift pump running too much would cause the VST to run out of fuel, unless it is sucking air instead of fuel

Did they grab the data that yamaha wanted them to?

[marchmadness]

Ok I will explain my thoughts....
1. The lift pump is suppose to cycle at idle no matter what.. So its not working right ,that's a problem why its doing it is another? But..
2. so I have two thoughts if , the pump just shut off at around three minutes,without any reason, it could just shut down at throttle up the vst uses up its fuel and the motor dies.
3.The pump running constantly at idle caused the pump to run in a loop passing through the relief valve. At that time its not pulling fuel, I throttle up the pressure built up ,leaves the loop open fuel never goes back into the vst tank and the motor dies.
And to answer the question I have no data as of yet
If I had to guess I think that the pump driver is turning off the lift pump when its not supposed to

[99yam40]

relief valve should hold the fuel pressure at 10 psi at the VST needle,
it should never allow it to drop below that while the pump is running , if it does it is defective and not reseating when the pressure drops
So as long as the lift pump runs and the VST needle opens when the float drops , the VST should fill.

I think with the VST full the motor should run for a few minutes.
now if the lift pump turns off and does not turn back on when it should the VST could get low.

Did you say you have replaced the Relief Valve again or just 2 years ago when you started this thread?

[marchmadness]

think it was new last year. The vst was full that’s why it was going through the relief valve. I don’t know how long the fuel would last but around a cup a fuel isn’t much. I tested it and it wasn’t leaking and opened around 10 psi. I really need to find out if the pump goes off. The pressure created by the lift pump running constantly keep the valve open.

[99yam40]

It will only keep the valve open when the pressure is above 10psi

we have told you before to monitor the fuel pressure leaving the lift pump going to the VST and the power to the pump.
you need to know when the ECU is telling it to run and the pressure will tell you if it is running and pumping fuel

the dates on this thread say you had the problem in 2016 and solved it back then. last year was 2017

[marchmadness]

Every time I think I have it fixed the next year it comes back. The mechanic checked the system and said that the fuel pressure and vacuum was good. I need to hook up the lift pump and see what’s it’s doing

[99yam40]

Every time I think I have it fixed the next year it comes back. The mechanic checked the system and said that the fuel pressure and vacuum was good. I need to hook up the lift pump and see what’s it’s doing

But did he check all of that when the problem was happening?

Seems like it ran OK from 07/16 til 05/18 or did you not run it in 2017

[marchmadness]

I have been waiting for my mechanic to go for a test ride and get data for Yamaha. The same problem has risen each year and never went away. I plan on hooking up a test light to see if the pump stays on.

[marchmadness]

I hooked up a test light to the lift pump and found that the l/p worked normal until key off and restart. Some times it would cycle and sometimes not .I ran the boat motors at 5k rpm no problem. So I changed the pump driver and there was no change. My mechanic hasn't come out for a ride so I plan on using the boat the rest of the year. If the problem occurs again I will be dumping these motors. So I don't know what else to say .Unfortunately I have no answers to post.

[walleye1]

Do you think it could be a key switch issue? He needs to check if the pump is getting power when this happens.

[Operaman]

I read quite a bit of the beginning of this and letting you know I did not read this entire thing, so, forgive me if this was said.

The fuel bulb you have been squeezing. Is it a Yamaha or a Mercury fuel bulb? Have you changed it out?

[oldmako69]

Curious about the bulb considering that one should not need to squeeze the bulb to restart/run the engine after a brief period with the engine shut down. I never use the bulb on my Port motor and it always starts and runs fine.

[99yam40]

I hooked up a test light to the lift pump and found that the l/p worked normal until key off and restart. Some times it would cycle and sometimes not .I ran the boat motors at 5k rpm no problem. So I changed the pump driver and there was no change. My mechanic hasn't come out for a ride so I plan on using the boat the rest of the year. If the problem occurs again I will be dumping these motors. So I don't know what else to say .Unfortunately I have no answers to post.

so does that mean some times it does not come on , or that it comes on and does not turn off.

I still do not see how a VST could run out of fuel if the LP pump runs too long, if that is what you are saying

[marchmadness]

The l/p never went off at throttle up. I’m trying to say sometimes it would cycle as it’s supposed to and sometimes it would just stay on. This has been the only real issue that I have found. The only thought I had about that maybe the pressure built up or heat caused evaporation . I just don’t know