Fuel pump question

[Halestorm]

2007 Tige RZ2 with marine power 5.7

When you turn the boat ignition on should the high pressure pump run ? I'm having fuel delivery issues and i can hear the low running so I disconnected it to see if the high pressure pump was working on its own... but when checking the pressure at the injection... I get nothing ... any help is greatly appreciated

[IDBoating]

Yep, HPFP must run when ignition is turned on. Otherwise the fuel rail won't have enough pressure to force fuel into the cylinders when the injectors open. There is a recirculation circuit to allow the "unused" fuel in the rail to come back to the low pressure side, thus allowing the rail and injectors to maintain pressure. Otherwise you'd have to cycle the HPFP off once the target pressure was reached, then back on again when it dropped, etc. which would lead to varying pressure and lack of control over how much fuel was actually injected. Gotta have constant pressure, which means running the HPFP all of the time.

[Halestorm]

Thank you ... pulled the pump and its done... wondering is I should change both pumps while I'm at it ...

[onetogofast]

For sure replace both. If you have a fuel issue, Eliminate the fuel issue.


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[IDBoating]

Also, confirm you have 12VDC at the pump's connector when the ignition is turned on. May as well confirm it's not an electrical problem while you're in there.

[Halestorm]

Will do... I have 12vt... changing both pumps... I'll update tomorrow