Fuel starvation yamaha f225

[99yam40]

I m guessing it’s working when I reprime and it starts and goes

think about it
If it is working why do you need to reprime

apparently it is not pumping fuel

[marchmadness]

if the lift pump wasn't pumping fuel the motor would not start? I ran the motor for about an hour after, fast slow idle not a hiccup? Is the computer telling the motor not to run the pump? I have looked for air leaks , I have pressurized the system. To me if the lift pump would either work or not ! Yesterday was the first time it did it and the motor wasn't even hot. I have changed that damm pressure relief valve so many times.

[99yam40]

you need to see if the pump is running and pumping fuel/pressure when it dies
what it does when it runs fine does not help find the problem

[marchmadness]

well before my summer is over I threw in the towel and brought the boat to a Yamaha certified Tech near me. He has been running it and testing, So far he has said my pumps are working ,pressures good etc. so he was running it and of course the motor was working normal. He told me he found a couple of small things and that he wanted to remove the vst. Well he was giving me back the boat and I we were going to go out for a run to see what it would do and the motor died. This guy is third generation Yamaha tech and he's pretty stumped. I hope a result will be found so maybe others can be helped.

[rodbolt17]

it is a simple system.
if you have the reprime the VST to restart it your not filling the VST with fuel via the lift pump.
you can actually use a multimeter to see if the lift pump is cycling.

[marchmadness]

So let’s say the lift pump isn’t cycling on restart. The computer is telling the pump to go on and off. So there’s a breakdown electrically?

[99yam40]

How do you know if the pumps runs when it will not start?
have you checked to see?

If it is not running,
how do you know the ECU is telling it to do what it is suppose to do when it will not start?
have you checked it?

testing needs to be done when the problem shows up

[marchmadness]

So the motor always starts because there is fuel in the vst. And the question is the ecu turning on the lift pump or is it staying in the off cycle when I throttle up?

[99yam40]

only way to tell is for you to monitor the + and - to the pump to see if the ECU is calling for it.

but that does not mean it is pumping fuel even if the ECU is calling for it.
monitoring fuel pressure should tell you if it is pumping liquid fuel

[marchmadness]

I haven’t posted in a while because I don’t have any answers. The boat has been at the mechanics for over two weeks. He says he can’t find anything wrong. He is trying to get a Yamaha rep to come and help. Yamaha has not to willing to help because they are not new. As far as he can tell everything works as it should. So if anyone has anything I could pass on to him or want to contact him directly I would sure appreciate it.😞

[oldmako69]

Tell him my engine does the same thing.

[99yam40]

you said he could not get the motor to act up .
but then you took him for a ride and it did act up.
did he do any testing when it acted up?
or just when it runs fine?

[marchmadness]

He got it to act up on the test tank. Before I took him out. What he did from there I’m not sure. He swapped out the ecu and cleaned the injectors trying to find something. He is like the rest of us left scratching his head. He was hoping Yamaha might be able to steer him in the right direction.

[oldmako69]

I ran my boat three times in the last two weeks. Each time I put several hours on the engines. On two of the three days I did the following:

1. Check oil.
2. Insert key and check voltage.
3. Start engines - without squeezing the bulbs.
4. Ran them several hours without turning the engines off. Ran, *****ed, ran some more, drifted, etc. Engines on all day.

Zero issues.

On the third day, I did exactly as above, but I shut one down for about 5 mins. I then started it up and attempted to get up and go. The engine promptly cut off. I squeezed the bulb and fired it back up, but it quickly shut down. I squeezed the bulb again, probably 15 times to get it firm. Fired up the engine and ran 42 miles home without a hiccup.

Makes no sense to me either.

[TownsendsFJR1300]

I ran my boat three times in the last two weeks. Each time I put several hours on the engines. On two of the three days I did the following:

1. Check oil.
2. Insert key and check voltage.
3. Start engines - without squeezing the bulbs.
4. Ran them several hours without turning the engines off. Ran, *****ed, ran some more, drifted, etc. Engines on all day.

Zero issues.

On the third day, I did exactly as above, but I shut one down for about 5 mins. I then started it up and attempted to get up and go. The engine promptly cut off. I squeezed the bulb and fired it back up, but it quickly shut down. I squeezed the bulb again, probably 15 times to get it firm. Fired up the engine and ran 42 miles home without a hiccup.

Makes no sense to me either.

Sounds like the line to the VST drains all the fuel once you turn it off...

Dunno if there's a check valve under the cowl for that or ?