Yamaha F115 fuel rail pressure

[GrouperGuru]

I have been working on tracking down an intermittent stalling issue upon deceleration after running for 30+ minutes on my 2003 F115 (1350 hours). I will take it out this weekend & see if I can cause the issue & monitor fuel rail pressure at the same time, but for now I have a general question.
Sitting in the driveway on muffs, I'm only getting 18psi when I turn the key to the on position. As soon as I start the engine, I am getting 37-38 psi. What are the possible causes of such low pressure prior to starting the engine?


Background info:

VST filter & other fuel filters replaced less than 50 hours ago.

Clean injectors installed about 20 hours ago.

IAC replaced last year (not sure anything was wrong with the old one).

Pressure regulator replaced 4-5 years ago due to major engine surging issue.

High pressure fuel pump replaced within +\- 1 year of pressure regulator.

Wiring harness & ECU also replaced around 4-5 years ago. Wiring harness had a badly corroded wire & ended up frying ECU.

Low pressure fuel pump is original.

Compression is good on all 4 cylinders.


So before I go further, I want to troubleshoot the low fuel rail pressure prior to starting the engine.

Thanks

 

[99yam40]

make sure your tester is correct.

Just because all of this stuff has been done it does not mean filters and screens have not plugged up from junk in the fuel or things have not failed

 

[GrouperGuru]

Got an extra set of hands out there this evening so I could watch the guage closer. When I turn the key on, I can hear the pump for a second & I get the correct 44 psi, but it rapidly drops to below 30 psi. Is this normal or should it hold 44 psi with the key in the on position?
I think the really low reading yesterday was due to user error with the pressure guage.

 

[Capt Ken]

It will not hold the pressure once the pump kicks off. It will bleed down.