2006 Yamaha F150TXR Low Pressure Fuel Pump Problem?

[DavidHNL]

2006 F150TXR with 420 hours - the VST tank and filter were serviced 1yr/100hours ago, also replaced the injectors at that time and all other 100hr service requirements.

A couple of weeks ago engine started cutting out at 5200 RPM, dropping to ~3400 RPM and has gotten progressively worse to the point of cutting out at 2500 RPM. When I pump the fuel bulb, it seems to help.

I tried running the engine with the fuel fill cap open and ran it on a new portable 5 gal tank - they symptoms remain the same.

I'm thinking this could be a low pressure fuel pump issue - could I check the input line vacuum pressure or check the output line pressure or check the output volume of fuel pumped for say 1 minute to determine if the pump is working up to specs?

Thanks in advance for any suggestions.

[99yam40]

monitoring fuel pressures of both pumps
and cleaning VST or replacing filters and screens if you find pressure problems might be a place to start.
Might check for a pressure relief/re circulation valve
along with restriction and air leak on suction side of lift pump

[pstephens46]

You say pumping the primer ball seems to help? Should help a bunch if lp pump is the issue. May be funk related. Especially if you had to replace injectors last year. 590 hours and never touched mine.