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Trev
Anonymous Poster
trevorska@gmail.com
Jun 18, 2009, 2:20 AM
Post #1 of 9
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Fuel pump not engaging
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I have a 2000 Chevy 1/2 ton pickup with the 5.3 motor. After replacing the fuel pump I have found that when I go to start the PU it usually takes 2-3 times of cycling the ignition to get the fuel pump to kick in and work. Sometimes it starts the first time and sometimes it takes a few tries.
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Hammer Time
Ultimate Carjunky
/ Moderator
Jun 18, 2009, 2:45 AM
Post #2 of 9
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Re: Fuel pump not engaging
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What you need to do first is determine exactly what the pump is doing. When you first turn the key on, the pump primes the system for 2 seconds. It then shuts off until the computer sees a tach signal from cranking. You need to use a fuel pressure gauge to observe just how it is acting. Cycle the key on a couple times without cranking and watch the gauge and see how quick it comes up to pressure. If you see no pressure this way, try cranking to see if the pump energizes this way. We need to know what is working and what isn't or whether the pump is just weak.
You could have a bad pump causing either low pressure or having a bad check valve allowing the fuel to siphon back into the tank, pinched hose, bad relay (running off oil pressure switch), etc We need to know how it is acting to know where to look.
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
(This post was edited by Hammer Time on Jun 18, 2009, 3:05 AM)
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trev
New User
Jun 18, 2009, 3:15 AM
Post #3 of 9
(1830 views)
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Re: Fuel pump not engaging
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Hammer Time--thanks for the reply. The fuel pump is not turning on at all. I can hear it when it does. It usually takes 2-3 cycles of the ignition switch before it turns the fuel pump on to where I can hear it. Once it turns on then the motor starts up.
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Hammer Time
Ultimate Carjunky
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Jun 18, 2009, 4:55 AM
Post #4 of 9
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Re: Fuel pump not engaging
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Will it turn on by merely cycling the key on and off or does it have to be cranking for it to energize?
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
(This post was edited by Hammer Time on Jun 18, 2009, 4:55 AM)
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trev
New User
Jun 18, 2009, 5:38 AM
Post #5 of 9
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Re: Fuel pump not engaging
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Usually it will not work by turning ignition only--it needs to start to crank and then the fuel pump will start to work. Like I say it usually takes 3-4 times of cranking it over (briefly each time) before it will energize the fuel pump.
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Hammer Time
Ultimate Carjunky
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Jun 18, 2009, 5:52 AM
Post #6 of 9
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Re: Fuel pump not engaging
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That really isn't making any sense on this vehicle. Some of them have a redundant fuel pump feed from the oil pressure switch but this one does not. You need to hook up a fuel pressure gauge and jump out the relay to determine if the pump can provide immediate pressure.
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
(This post was edited by Hammer Time on Jun 18, 2009, 5:53 AM)
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trev
New User
Jun 18, 2009, 6:06 AM
Post #7 of 9
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Re: Fuel pump not engaging
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This all started happening after we replaced the fuel pump. We then found that it wasn't a bad fuel pump, but rather a bad connection. I replaced the connector and left the new fuel pump in the vehicle. It started having this problem about a month or so after we replaced the fuel pump.
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Hammer Time
Ultimate Carjunky
/ Moderator
Jun 18, 2009, 6:48 AM
Post #8 of 9
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Re: Fuel pump not engaging
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The pump may have a bad check valve in it but until you can give me some of the info I asked for, I can't tell you if that is the case. You HAVE to use a fuel pressure gauge to diagnose this problem.
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
(This post was edited by Hammer Time on Jun 18, 2009, 6:48 AM)
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trev
New User
Jun 18, 2009, 7:23 AM
Post #9 of 9
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Re: Fuel pump not engaging
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Help me to understand why a bad check valve would keep the fuel pump from energizing? It seems like ti would be an electrical problem or a relay problem of some sort--of course I know just enough to be dangerous. Thanks for your input so far.
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