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Mike V.
Mike V., Auto Technician
Category: Chevy
Satisfied Customers: 25351
Experience:  25 years automotive experience, Certified Subaru Tech and Nissan factory trained.
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I have a 2002 chevy astro 4.3 vortec. Runs fine but when i

Customer Question

I have a 2002 chevy astro 4.3 vortec. Runs fine but when i let it sit for a day or two i haveto prime thefuel system to get it to start. Now if i drive it everyday it starts with no problem what can cause this condition?
Submitted: 2 years ago.
Category: Chevy
Expert:  Mike V. replied 2 years ago.

Hi there,

When it starts does it run rough for a second or two or nice and smooth after you prime it?

Customer: replied 2 years ago.
It runs rough. But goes away after i dont know how long. If driven everyday then no hard starts and no running rough
Expert:  Mike V. replied 2 years ago.


Only a couple of things will cause this. Either the fuel pump is letting the fuel drain back to the tank or the spider injector may be leaking. The rough running at start up kind of indicates that one of the cylinders may be flooding with the extra fuel, then clearing up and running fine. You need to put a fuel pressure tester on it and try to determine which it is to be 100% sure. The injectors are known to leak on these, but I would still rather be sure.

You have to set up the pressure gauge with a valve in it, this way you can fire the van up and get the pressure up. Then turn it off and close off the valve. If the pressure drops off when the valve is closed, then it's an injector issue. If not, then you can assume it's a problem with the check valve in the fuel pump.

Please let me know if there is any more I can do to help you from here.

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Customer: replied 2 years ago.
Ok and so somwthing called the fuel regulator would be a factor?
Expert:  Mike V. replied 2 years ago.

It is possible if it's leaking. With the way it's running though once you get it started it's not likely in my opinion. The fuel pressure test should let you know right away if the pressure regulator is a problem.

Key on but engine off the pressure should be 55-2 psi

Customer: replied 2 years ago.
Ok thanks. I will get fuel pressure test
Expert:  Mike V. replied 2 years ago.

You are very welcome, please let me know if there is anything more I can do to help.

Please remember to rate as well.

Thanks so much!