vjjack04

Ok. I am trying to narrow down a fuel problem I am having - I recently changed engines yet used the same fuel rail (1997 C5). The fuel rail has the fuel pressure regulator on it. I am using the factory fuel lines. My question is what is the little nipple connector that is on the front of the fuel pressure regulator used for (beside ther regulator adjust nut)? I thought it was part of the EGR/AIR system I deleted and I have a small rubber cap over it. Should I have a vacuum connected to this or should it be open?

slow

iTrader: (7)

it should be connected to a vacuum line running to open atmosphere.

Ryan

123sugey

It gets plugged into the intake tract. It cannot be plugged

C5Fire

I have a 98 C5 with the same rail. It gets hooked to intake vacuum.

97F1R408

iTrader: (2)

At idle engine vacum is high, under acelleration or a load it decreases, it is designed so when you accelerate or load the engine the fuel pressure increases. With it disconnected the fuel pressure will be at max which isnt nessecarilly bad or cause any running issues.

No Juice

iTrader: (11)

yeah you set the base fuel pressure to 58psi max at idle with the vacuum line off. Then with it connected it will reduce fuel pressure at idle to help it idle and it won't be so rich.

Thats how it was explained to me anyways

luch90

iTrader: (1)

that nipple should go into your intake tract or be vented to atmosphere. it is not a vacuum controlled pressure regulator-that is just an atmosphere vent that is vented into the intake tract in case of diaphram leakage fuel goes into the intake versus on the hot engine