Every time I shut the engine down the fuel pressure drops to zero. I have rebuilt the TBI unit. I have installed a pressure gage on the fuel line. If I pinch the hose above the gage, the pressure holds. If it pinch it below the gage, it goes to zero quickly. It did this before I rebuilt it too. I have checked the regulator with a vacuum pump. The diaphram is ok. There is a small orifice in the regulator cover that goes to the return line. If I plug this orifice and pull a vacuum, the pressure holds.

What is this orifice for? The orifice is the only leak I can find. When I disconnect the fuel line there is still fuel in it, so I figure if there is a check valve in the pump that is not a problem.

Is there a check valve on the return line that could be bad?

Should I put one in?

91 camaro rs 305

Thanks in advance.

Matt

[This message has been edited by mattf (edited August 26, 2001).]

 

I just read my Haynes book and it said that TBI has a constant bleed feature because of the pressure regulator.