That's not a good indication of fuel pump problems, but to be sure your pump is working good, put a simple fuel pressure gauge on the test port on the engine's fuel rail, turn key to on, and check that the pressure is as specified by Chevrolet. A failing pump will act badly more than just "sometimes".
Scan the computer for fault codes. probably a tune-up with new plugs and possibly plug wires might clear up the stalling.
Well the fuel pump and filter can be changed and most cars have a test port to hook a gauge to test pressure. Need about 45psi to make run. With fuel injection
Try having the fault codes read to find the sensor responsible
SOURCE: Random stalling, then won't start
was fuel filter replaced? it also could be a bad coil pack
SOURCE: 2000 blazer 4.3 hard to start (fuel problem)
Do you have the fuel tester hooked the in the overgrown air valve on the fuel rail in the back of the engine? Or do you have the fuel line unhooked in the back and hooked to the pressure pump? You want the fuel pressure to be in that 60 lb range so if you are hooked into the pressure valve on the fuel rail allowing fuel to go through, then I am betting it is the fuel pressure regulator. To get to that, you have to take the throttle body off and take the plastic plenum that covers the injector packs. On the back of the mount where your six pack of injectors are sits the pressure regulator. If it is faulty then it is dumping fuel instead of holding the pressure like it should.
Get a Chilton or Clymer manual and it shows you in pretty good detail how to fix it. I've done it to my 98 S10 with the same engine.
If you unhooked the fuel line so you are losing pressure from the line back to the pump then I would say your pump is letting fuel back to the tank when it shuts off. My money is on the first possibility though.
Good luck
SOURCE: 92 Chevy Suburban Electrical Fuel System
Check fuel flter at fuel pick-up intank (looks like a small wire sock). Remove fuel filter and fitting at fuel rail. Blow out fuel lines w/about 35lbs air press. Ck electrical @ relay - should be 4 connectors - one is key on hot/one is always hot/one is ground and last is hot to fuel pump. Good Luck
SOURCE: 04 Chevy Cavalier fuel pump
The fuel pump relay is buzzing.the possibilities are:---
1) the relay itself is faulty.
2) The relay is not connected properly.
3) the relay ground wire is connected to ECU (electronic control unit also known as cars computer).
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You say relay is just replaced,so relay is good.Check the relay connection,remove the relay clean the relay and reconnect it.Then see if same problem is noticed like relay buzzing,then in that case the relay ground wire connection has to be checked.The ground wire is either loose or there is cut in between the ground wire. At the fuel pump connector, the gray wire is for the
fuel pump. The fuel pump relay will energize for 2 seconds each time the key is
turned on. Test for power on the gray wire by turning the key on, wire should
power up for 2 seconds.Test at the fuel pump connector under the car at the fuel tank. Touch the voltmeter red lead to the thicker gray wire. Touch the black
lead to a black wire or chassis ground (bare metal). Turn the key on and you
should have 12 volts for 2 seconds.A-black wire is ground. C-gray wire is fuel pump power
feed. Measure voltage at these two terminals when the key is turned on.If there is no voltage then by pass the fuel relay by jumper.Pull relay and look at the bottom of the relay. Find
the terminals labeled 30 and 87. Jumper the corresponding terminals together to
bypass relay.You will see pins 30,85,86 and 87.
85 and 86 are power and ground to the relay coil
(turns the relay on). 30 and 87 are the switch contacts within the relay (main
power comes into and out of the relay to the fuel pump on these terminals)
Placing a jumper from 30 to 87 should supply power to the fuel pump.
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Now this is the main test result:--- If pump did not run with voltage applied, you will
need to replace the fuel pump.By bypassing the relay,then in that case the fuel pump is faulty and that is causing the problem.Pin 86 gets its ground from the PCM (computer) It will
only get a voltage for 2 seconds when the key is turned on, will have a ground
full time while cranking the engine or with the engine running.But if pin 86 has voltage to it forever,then ground is short.It should have voltage only for 2 seconds when you crank the car/engine.
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But if all checked out ok then it can ECU fault.The ECU itself needs to be scanned and checked.
ECU/PCM/ECM are one and the same thing.
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This troubleshooting will help. Thanks.Helpmech.
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