Yamaha high or low fuel pump?

[orionn]

Working on buddies 2001 Z200TXRZ
He lost RPM's and limped it home since then this what we did so far:
sent injectors to the injector man for service
replaced the MYSTERY filters
cleaned O2 sensor
cleaned VST and found no screen on pump filter (not sure if it was removed by previous owners or mysteriously disappeared)
replaced canister
replaced water/ fuel separator

engine will run for only a few seconds before dying
connected the YDS and Engine Monitor results:
all sensors - Normal
Fuel Pressure (5.0+-0.8) 1.2 MPa
Fuel Pressure (725+-116) 174.29 PSI

My question is what fuel pump is measured by the YDS? Could this issue be from the High or Low or BOTH FPumps.

Thanks for any input...

 

[orionn]

Update:last week

Hooked up an external tank and fuel pressure gauge to the VST and got the following results:

48-50 psi at shredder valve : good

Connected the YDS and had an increase in results without an increase in performance (did run a few extra seconds before dying)


main fuel system / external Tank
Fuel Pressure (5.0+-.08) 1.2 MPa / 2.77
Fuel Pressure (725+-116) 174.29 / 401.88

At this point I am guessing it is the HP FP failing

All filters have been replaced including the canister and the small HP filters...

update to the update = update2

Today
My buddy purchased a used HP fuel pump minus the drive gear/cam shaft assembly
Still no increase performance - actually now registering only 24psi on the YDS

Before he opts out and contacts a mobile mechanic could the lack of fuel pressure come from drive gear/cam shaft assembly? Looks like a small roller at the end of the HP pump that runs off the shaft - does this generate the pressure?

Also going to bypass the check valve - eliminate all possibilities.

[FONT=verdana, geneva]Thanks for any input / any other trouble shooting ideas?[/FONT]
[FONT=verdana, geneva]replaced all filters: new water separator new fuel lines , replaced all small filters , new plugs, injectors serviced, connected to an auxiliary tank and still it wont idol or stay running...[/FONT]

This motor is driving us NUTS.....lol