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Dan
Dan, Technician
Category: Chevy
Satisfied Customers: 23743
Experience:  Independent Shop Experience, 2 Year Automotive Diploma, & Access to Information Database
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My 99 Chevy Tahoe's fuel pump keeps running after I turn the

Customer Question

My 99 Chevy Tahoe's fuel pump keeps running after I turn the ignition off. The only way to get it to shut off is by pulling the ecm fuse or disconnecting the battery. Even pulling the fuel pump relay doesn't shut it off. It is a 5.7l 350.
Submitted: 1 year ago.
Category: Chevy
Expert:  Dan replied 1 year ago.

Hello, my name is***** do you know the fuel pump keeps running?

Customer: replied 1 year ago.
I can hear it. I'm pretty sure it's the fuel pump. It's loud under the truck. Loudest behind the driver door by the gas tank and I can hear a buzz in the engincompartment. The only way to get it off is to pull the ecm fuse
Expert:  Dan replied 1 year ago.

Are you 100% sure you are removing the fuel pump relay? Have you tried to remove each fuse and relay one by one to see if anything else shuts it off?

Expert:  Dan replied 1 year ago.

Because if it really is fuel pump that would mean the gray wire that goes between fuel pump and fuel pump relay has shorted to power which is unlikely.

Expert:  Dan replied 1 year ago.

The ECM B fuse powers relay then it powers the fuel pump.

Expert:  Dan replied 1 year ago.

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https://www.dropbox.com/s/yvmwxism2zc9pqt/fuelpumprelay.png?dl=0

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Here is a picture of the fuel pump relay so you can be sure it is the right one. If removing fuel pump relay doesn't help disconnect gray wire at pin A3 fusebox connector to verify pump shuts off, if not replace wire between pump and fuse box. If it does shut off the fuse box has internally shorted and needs to be replaced. Let me know if you have more questions or if there is anything else I can do to help .Thanks.

Customer: replied 1 year ago.
The fuel pump relay in the engine compartment fuse box is the relay I pulled. When I pull that yes it still runs. In the diagram you sent me there isn't anything labeled a3. I want be sure I clearly understand you before I pull it.
Expert:  Dan replied 1 year ago.

I do not see anything in wiring that shows a common wire. Lets start with wiper problem and see where it leads. At wiper motor black wire should have ground, yellow should have power, and purple should have power with wiper motor in high position. Let me know what you find, thanks.

Customer: replied 1 year ago.
I'm not having a wiper problem. I'm havin the fuel pump problem
Expert:  Dan replied 1 year ago.

Sorry about that. You need to remove the connector from fuse box then pin A3 is terminal on connector going to fuse box with a gray wire. If pump shuts off when disconnecting gray wire you know the fuse box has internally shorted, if not the wire has shorted. I think the problem is more likely the fuse box then wiring. Let me know how it goes or if you run into more questions, thanks again and sorry about confusion.