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Alex, ASE Certified Technician
Category: Chevy
Satisfied Customers: 1161
Experience:  ASE Certified Master Technician, L1 Advanced Level Specialist
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Chevy S10: The fuel pressure regulator..4.3L

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The fuel pressure regulator on a Chevy S10 4.3L engine has a little tube on the back. Is it supposed to be connected to something or plugged?
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The nipple on the fuel pressure regulator should be connected to a manifold vacuum source. You should see a vacuum hose nearby that has come disconnected from the regulator. If there is no vacuum hose to the regulator it will not work properly.
Customer: replied 6 years ago.
I do not see any hose I can connect it to. When I took off the plenum the only hoses I saw were the injector hoses from the injector assembly to the injectors. Where do I find the vacuum source, and what type of hose do I use?
I did more looking and that nipple actually should not have a vacuum hose attached to it. This vehicle has a CPI engine and the fuel pressure regulator is already under manifold vacuum due to its location. So that nipple should not have a vacuum hose attached to it.
Customer: replied 6 years ago.
Thanks for the info, but it leads me to another question. Do I need to plug that nipple or just leave as is? Thanks again, I really appreciate your knowledge.
Just leave it open. It needs to be open to atmospheric pressure.
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