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Q: Possible fuel pump problems?

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I have a 1994 Chevy 2500 4x4 with the 454 big block. We have replaced countless sensors, the cap and rotor, the throttle body sensor, a knock sensor, etc. I am beginning to think the fuel pump/filter may be an issue.

The truck runs great when we can get it started. However, it's getting the vehicle started that's the issue. If you dump a bit of gas in the carb it fires right up. Then you can shut the vehicle off and fire it right up again. However, if the vehicle sits overnight, or for a few hours (especially in the rain or morning dew), it once again will not start until a small amount of gas is poured in the carb. Could this be a fuel pump failing, or possibly something else? It's throwing me off, because once the truck gets started it runs like a champ and has no problems what so ever.

My car has 200000 miles.
My car has an automatic transmission.

A: Assuming you have the stock equipment still...

Assuming you have the stock equipment still in your truck, it should have come with throttle body fuel injection and not a carburetor. If this is the case, you likely have a low fuel pressure issue that is preventing the fuel system from priming upon starting. First, try checking to see if you hear the fuel pump come on when just turning the key to the on position (should be a slight buzzing sound). If this does come on, then you know the fuel pump is working and getting power. Secondly, you may want to check the fuel pressure. The fact that the truck will run once primed with fuel suggests that you may have a fuel pressure regulator problem as it is able to maintain once it is initially primed with fuel, but unable to do this on it’s own upon start up. Here at YourMechanic, we can have a technician come to your home or office to inspect and diagnose this issue for you, and make or suggest the necessary repairs.

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