I have a 1993 chevy s10 with a 2.8L motor in it. The oil pressure sensor blew out of the side of the motor and I replaced it. Now my question is how come when I replaced it and plugged it up up the fuel pump came on even when the ignition was off and the key out of it and didnt turn off until I unplugged the oil pressure sensor. Can someone please help me.
Sounds like you have the wrong sending unit, it had two terminals reversed when it was made, or the plug is in backwards.
GM had some systems that ran the fuel pump off a terminal on the sending unit as a safety cutout. If the vehicle was in a crash that ruptured a fuel line, there would be no fuel pressure so the engine would stall. When it stalled, there would be no oil pressure so the switch in the sending unit would turn off and turn off the fuel pump. That would stop it from pumping raw fuel onto the ground.
May, 3, 2011 AT 12:42 PM
So why is the fuel pump coming on and staying on as long as tht sensor is plugged up even when the ignition is off? Also the truck wont even start since that oil pressure sensor went out and I replaced it.
May, 3, 2011 AT 5:55 PM
I agree with doc on the fact that you likely have either a bad or the wrong oil sender. It is used as a redundant power supply for the fuel pump but it IS NOT a low pressure cut off. It does not have the ability to interrupt the fuel pump, it can only power it in the case of a relay failure.
May, 4, 2011 AT 3:35 AM
Well the only other sensor is for an s10 that has a z or w in like the 7th spot of the vin number of the truck and my vin number doesnt have a z or w in it at all.
May, 4, 2011 AT 11:11 AM
That would be because both of those choices are for the 4.3 engine options and you have the 2.8
May, 4, 2011 AT 2:46 PM
Well then there is only one sensor for my truck and thats the one I got.
May, 4, 2011 AT 3:05 PM
If unplugging it sender stops the fuel pump, then the sender is the problem.