f115 fuel pressure trouble

[boats.net]

It should have 12 volts across the 2 wires going to pump when turn key on.

[cyrillefrenchy]

yes, 12 volts across as soon as you try to crank, no delay, and again, fuel flow shooting hard off the fuel rail.
let us know the result.
frenchy

OK! So I had 12 volts and no issues this weekend starting and running. I did press the pressure relief valve on topp of the VST tank and I noticed it had lots of air. I did it prior to heading out and also after returning. Both times it had a lot of air being releases. Is that normal? I thought you should only have to bleed the air out of that after you clean and renistall.

anyone should I need to bleed the air repeatedly?

[cyrillefrenchy]

i don't think you should have some air on the high pressure side of the fuel line, only strong straight fuel flow.
if you have air it will take longer time to restart, time for the pump to evacuate all the air and to put the fuel ram under pressure again, especialy on these engines with no return fuel line.
usually on fuel injected engines, the fuel pressure is around 35_45 psi.
air is compressible, the pump will have to run longer to reach this pressure, making the engine harder to restart.
try this : squizz the bulb with the fuel line disconnected where it goes to the vst and look, clean clear strong fuel flow should come off, with no air.
after try again with the engine running, it should be the same.
the low pressure fuel pump could throw you some air in the line.
let us know
frenchy

I tested the pump this weekend and it was fine. It had 12 volts with key on and was running. Still wouldn't start, I removed the filter on the back of the boat and checked the gas there. It was clean and good. Reinstalled the filter squeezed the ball firm and it cranked right up.

You think this could be vapor lock problem in the low pressure pump?

[cyrillefrenchy]

the vapor lock is when the gas is boiling in the line or in the carburator bowl.
i don't think this is a vapor lock problem , outboards engines are running way colder than cars, there is no hot parts on outboards like exhaust manifolds..
you took the filter off, checked and squizz bulb, after it get hard the engine restart, right? i think you have air in the line and it is harder to evacuate the air in the fuel line on fuel injected engines than carburated.
now try this.
after engine stopped for a long time and not supposed to restart, disconnect the fuel line just before the vst tank, squizz the bulb for a long time to make sure the fuel line is bled with no air at all, reconnect, squizz again till the bulb is hard and try to start...
let us know.

I spoke with Yamaha customer relations today. They think it may be a bad fuel pressure regulator not relieving pressure and not allowing the VST to pump gas.

Can someone tell me how to test the fuel pressure regulator?

[herb.wilson@uno.edu]

My manual says check the pressure regulator by checking the fuel pressure. Make sure the vacuumm line from the intake manifold is hooked up solidly. AS I understand it the regulator main job is to limit pressure because the pump produces more than is needed. Try http://www.buzzle.com/articles/sympt...regulator.html

Is there a way to test if the boat will not start?

[captron904]

Did you ever find the issue?