06 F225 fuel issues

[guitarzan413]

Hello all,
I am working on a 2006 Yamaha F225 TXR SER# 693X1026640K. I'm not sure if all those are needed for id but thats all on the sticker.
Now to the problem: I had a major water in fuel tank issue. Finally got all cleaned, new lines, filters(3 total), and fuel pumps. feed and vst pump. Went to test on water and ran for a few minutes then slowly lost rpm and dies. If I cycle key, it will start and run for about 60 seconds then loses rpm until dead. Got it back home finally, put on pressure gauge at schrader valve. It runs up to 40 psi with key on but loses pressure as soon as key is off. I noticed as rpm is lost, so is fuel pressure. Drops from 40 to zero. Cycle key couple times and it comes up but wont hold when shut down but it will start and run until pressure loss. I also noticed my feed pump is running constantly with engine on. I know they are supposed to cycle as needed. Do I have an issue inside vst where the fuel is being returned constantly causing feed pump to run all the time? Or do I have a high pressure pump that's failing inside tank?. Should I remove vst for inspection of inside components? Could a bad float or needle/seat cause psi issue as well as feed pump running constantly? I don't want to throw parts at it, but I am lost here.

Thanks in advance for any clues!!

Spencer

[fairdeal]

somewhat of brain overload there for me - but here's a couple thoughts

- who cares what the rail pressure is a few minutes/seconds after you shut off the engine - its off -
doesn't need any rail pressure

- now it you are seeing the rail pressure drop to 0 while you are trying to run -
then that's a problem. Could be the HP pump isn't working,
or could be "simply" the VST is empty

- the low pressure pump doesn't run "as needed"
it runs 10 seconds on, 20 off below 1200 rpms
above 1200 rpms it runs constantly

- if you had a major water problem, IMO opening up the VST for an inspection is just common sense

- getting back to "maybe the VST is running empty",
you have a free, always available diagnostic tool:
your primer bulb.
Squeezing it will allow you see if fuel can be moved to the VST,
or if the LP pump has already kept it full.

[guitarzan413]

I'll check the lift pump cycling at lower rpm. Rail presssure is dropping to zero while running. Primer ball stays firm and squeezing makes no change. I did notice cycling the key helped me get back to dock.

[fairdeal]

Rail pressure is dropping to zero while running. Primer ball stays firm and squeezing makes no change. I did notice cycling the key helped me get back to dock.

if the rail pressure drops AND simultaneously you can't pump any more fuel into the VST -
then you can forget about the low pressure pump -
the problem is with the high pressure pump.

I don't know what to make of the "cycling the key" clue;
yes, when you first turn on the key, the ECM tells the HP pump to run for a few seconds
but once the flywheel is turning, the ECM keeps the HP pump constantly on.

I would definitely open the VST and have a look -
some people with "water problems"
have ended up with a HP pump that looks like this:

[guitarzan413]

That's pretty much what my pump looked like. Just finished install late yesterday and put on water this morning. She runs like a champ! Thank you for your help!

[99yam40]

strange how you said in your original post " Finally got all cleaned, new lines, filters(3 total), and fuel pumps. feed and vst pump."
did you just now replace the pump in the VST?
I thought you said you did that before posting about your problem