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Tim's Auto Repair
Tim's Auto Repair, mechanic
Category: Chevy
Satisfied Customers: 15921
Experience:  Have owned a repair shop for 25 yrs.
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Chevrolet S10: my fuel pump will not stop buzzing after I turn

Customer Question

my fuel pump will not stop buzzing after I turn on key. It will run vehicle but the vehicle will quit eventually
Submitted: 6 years ago.
Category: Chevy
Expert:  Tim's Auto Repair replied 6 years ago.


if you turn the key on and don't start the engine.....the fuel pump will come on and stay on,,is this right?it runs with the engine not running?tell me all you have tried


Customer: replied 6 years ago.
without starting the engine, but turning the key on, the fuel pump never stops humming. It will studder a time or two. Also, the truck will run but then decides to quit and there is no humming at that time. After sitting for a little while, the pump will make it's noise again and the truck will start.
Expert:  Tim's Auto Repair replied 6 years ago.

ok have replaced the fuel pump relay?

Customer: replied 6 years ago.
no, I swapped it with the horn relay
Expert:  Tim's Auto Repair replied 6 years ago.


does the engine light stay on?if so,can you give me the computer codes?

Customer: replied 6 years ago.
yes, but I don't have the codes
Expert:  Tim's Auto Repair replied 6 years ago.


if you don't have a scanner,,auto zone and most parts stores will scan it and give you the codes for free,,these codes may give a clue to the problem..let me know

Customer: replied 6 years ago.
Wait a minute, Thats what I am paying you for. I just want to know if the problem is the fuel pump or the regulator or whatever. I can't leave and get codes and log back on. You are saying you can't help me without them? The light has been on for a while already before I had these troubles
Expert:  Tim's Auto Repair replied 6 years ago.

ii cant scan it from can log back on.,this problem is not the regulator..though the fuel pump may be bad and sticking.this may be why it will quit running after the pump gets hot.,if the fuel pump is staying on,this would mean the computer [pcm/ecm]is still sending a signal to the relay when it is not suppose to.this would make me think the computer is bad from what you are saying...this may help you


Fuel Pump Electrical Circuit

When the ignition switch is turned to the ON position, the PCM energizes the fuel pump relay for 2 seconds allowing the fuel pump to pressurize the fuel system. If the PCM does not receive any ignition reference pulses (engine cranking or running) within 2 seconds, the PCM de-energizes the fuel pump relay; this causes the fuel pump to stop. An inoperative fuel pump relay can result in long cranking times.



Wiring Diagram


Customer: replied 6 years ago.
I pulled relay and engine shuts off but the humming continued does that help
Expert:  Tim's Auto Repair replied 6 years ago.

well if this is the case...the fuel pump is not the cause of the humming...when you pull the relay,the fuel pump has no power