Fuel pump always running
Thread Starter
Navigator
Joined: Sep 2013
Posts: 9
Likes: 0
From: Omaha NE
Fuel pump always running
95 LT1
Even with the car off key out the fuel pump runs. If I disconnect the fuel pressure sensor it stops. Car runs fine with it disconnected. I replaced it recently, but if I connect the original cracked one to the harness, even with no key in it turns on the fuel pump.
All started when I had a burnt plug wire so I replaced the wires and coil. Noticed the Crack sensor so replaced it to.
Any ideas on what would cause this?
Even with the car off key out the fuel pump runs. If I disconnect the fuel pressure sensor it stops. Car runs fine with it disconnected. I replaced it recently, but if I connect the original cracked one to the harness, even with no key in it turns on the fuel pump.
All started when I had a burnt plug wire so I replaced the wires and coil. Noticed the Crack sensor so replaced it to.
Any ideas on what would cause this?
Le Mans Master
Joined: Sep 2013
Posts: 6,192
Likes: 750
From: near the thumb in the mitten
The cracked one is broken. What is the condition of connector? Oil switch will power fuel pump once oil pressure is above about 5 psi. If new oil switch is shorted or incorrect it would cause fuel pump to run when plugged in,
Thread Starter
Navigator
Joined: Sep 2013
Posts: 9
Likes: 0
From: Omaha NE
Connector appears in good shape. When connected up, it appears to show pressure correct. No pressure when not running, pressure when running. The original cracked down near the base. Not at the top.
Le Mans Master
Joined: Sep 2013
Posts: 6,192
Likes: 750
From: near the thumb in the mitten
I suggest to verify you got correct replacement, and that its not defective. There are 2 oil switches, 1 is for gauge and the other is for warning light and to bypass fuel pump relay. The second one is what you should have replaced.
Team Owner
Joined: Sep 2003
Posts: 25,381
Likes: 2,735
OP - if you still have the box for the part you replaced post brand/part# to ease the ID for you. If you don't maybe the invoice? Post a snapshot of your bad/broken switch/sender for ID. Maybe make a note to the wire colors to the part. There's several ways to help you.
Instructor
Joined: Feb 2016
Posts: 111
Likes: 10
Hello. Realize this is an old post, but did you ever resolve the problem ? I had a similar issue, when changing the oil pressure switch on my 96 LT1. O:il press gauge seemed to fluctuate some, so decided to change the switch, with a new one from A1 auto parts. Plugged new switch in, and the fuel pump ran all the time, even with key off. New switch was shorted. Replaced with AC Delco switch, and constant running went away, but believe stilll have an issue with it. Key on, and pump energizes for 2 seconds, as it should, but starting takes about another 4 seconds, indicating to me that oil pressure has reached 4psi, and has activated the Fuel Pump relay, not sure how to tell exactly. Subsequent starts, and fires right up, but if sits for a few hours, will take about 5 seconds of cranking
Instructor
Joined: Feb 2016
Posts: 111
Likes: 10
Hi. Realize this is an old post but, did you ever resolve the issue with your fuel pump running with the key off? Reason I ask, is I had a similar problem, when replacing the oil pressure switch
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