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Jay
Jay, Nissan Technician
Category: Nissan
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Experience:  20+yrs experience with Nissan & Infiniti Trained & Certified.Currently still working for Dealer
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98 pathfinder: oil pump switch/power interrupter..fuel pump relay

Customer Question

98 pathfinder 3.3L fuel pump runs after car is turned off. will oil pump switch/power interrupter solve the problem? already replaced fuel pump relay. Where is this switch located?
Submitted: 3 years ago.
Category: Nissan
Expert:  HighwayRepair replied 3 years ago.

HighwayRepair :

Hello, there is no interaction between an oil pump switch/power interrupter and the fuel pump circuit. The fuel pump relay a;ways has power from Fuse 17, and gets grounded from the ECM, to turn the fuel pump on. If the fuel pump stays on all the time, the ECM is either grounding the relay at the improper time, or there is a short to ground on the wire between the ECM and the relay, or there is a short to power on the wire between the relay and the fuel pump. Do you have a voltmeter and ohmmeter so we could perform some electrical diagnosis?

Customer :

yes i have a voltmeter. what is the ecm (I have my haynes and can look it up.

Customer :

if I have to. several people stated that the fuel pump is started through the relay, but the oil pump switch operates it after the motor starts and when oil pressure goes down after you shut off the ignition, then it shuts off the fuel pump.

Customer :

oil pump switch/ power interrupter , but I can't find a location for this switch. think on top of motor above the oil filter...

HighwayRepair :

The ECM is the engine control computer, it monitors multiple sensors and controls the engine electronics. I cannot find an oil pump switch on the electrical circuit for the fuel pump, perhaps my wiring diagram is incorrect/incomplete. but HERE is the wiring diagram I have access to.

Customer :

it is on the schematic in the haynes if you look at the fuel pump, there is shown a connection to the fuel pump relay with a black/blue wire and a single black wire ending in a bullet (which this chart does not have a ledger so can't look up) assuming since is black is hot.

Customer :

as supposedly this switch gives direct access to the battery?

Customer :

this switch has a one pin connector on the top of it.

Customer :

I have read my haynes front to back. the oil pressure switch is mentioned, but no location given, not actually named on schematic is why I took a chance on this.

Customer :

hello?

Customer :

The car runs great, but sometimes, not every time, when you turnoff the ignition, the motors stops, but the fuel pump does not. restarting and turning off somtimes turns off fuel pump, or sometimes remove gas cap and that will turn it off.

Customer :

I NEED AN INFORMED TECHNITION......NOW

Customer :

great, i am signing out. if anyone figures this out send me an email. i have things to do, not sit and wait on

Customer :

someone who disappears

Customer :

answer is not acceptable. i wanted to locate the switch on the motor so it could be replaced.

Expert:  Jay replied 3 years ago.
Hello and thank you for using JustAnswer.com

Sorry for the delay in response. HighwayRepair is new here.

The oil pump is not electric on your truck, it's mechanical. The only thing electric is the Oil Pressure switch. That is for the oil light on your dash and does not turn the fuel pump on and off. The Ecm turns the fuel pump on and off, based on the Cam sensor operation.

Do you have any more questions on this? Let me know, Thanks Jay!
Customer: replied 3 years ago.

THE SWITCH I AM REFERRING TO IS WIRED DIRECTLY TO THE FUEL PUMP AND TO A "OIL PRESSURE SWITCH" OR POWER INTERRUPTER SWITCH WHICH IS SCREWED INTO THE SIDE OF THE ENGINE.

 

NO ONE HAS GIVEN ME THE LOCATION OF THIS SWITCH....EXCEPT MY LOCAL MECHANIC TO WHOM I TOOK THE CAR TODAY.

 

THE SWITCH SERVES A DUAL PURPOSE: IN CASE THE OIL PRESSURE DROPS BELOW A SAFE LEVEL, IT WILL SHUT DOWN THE FUEL PUMP TO PREVENT BURING UP THE MOTOR.

THE IGNITION SEQUENCE ECM ETC STARTS THE FUEL PUMP, BUT BECAUSE IT IS WIRED TO THIS SWITCH OPERATES BY IT OPENING AND CLOSING ACCORDING TO OIL PRESSURE. BECAUSE IT IS STICKING AND NOT TURNING OFF THE FUEL PUMP WHEN THE CAR IS TURNED OFF, THE FUEL PUMP KEEPS RUNNING.

THIS SWITCH IS NOT THE THREE WIRE SWITCH THAT SENDS INFORMATION TO THE DASH AND OPERATES THE IDIOT LIGHT.

I DID NOT GET THE ANSWER FROM YOU OR ANYONE THERE THAT I NEED...THE EXACT LOCATION OF THE SWITCH..

 

 

Expert:  Jay replied 3 years ago.
This is a 98 Pathfinder right? The oil pressure switch if that is what your referring to the one by the oil filter, only has only one wire going to this. Is this a US model? There is no oil pressure cut off switch that I know of on this year, and I have been working on these for 20 years!

Let me know, I am just wondering at this point. Thanks Jay!
Customer: replied 3 years ago.

wonderful. I bought the switch from autozone.

it has only one wire connection.

it is not by the oil filter.

 

why won't the fuel pump stop running after I turn off the ignition?

I was told, the fuel pump is started through the switch,

through the fuel pump relay housed in the fuse box on the passenger side of the car,

i replaced the relay and the problem continued.

 

I also researched and found....after the motor begins running, the fuel pump is kept running by the oil pressure cut off switch which is wired from the relay....it is one wire leading out to the switch which is installed somewhere above the oil filter and I think I will have to remove the power steering pump in order to access it.

 

what I wanted from you was the location of this switch

and to solve the problem of the fuel pump that won't shut off when you turn the ignition off.

 

 

yet you are saying this switch does not exist. it exists on my wiring diageram in my haynes and on a diagram sent by another one of your experts.

from all my research, it is a mystery switch that exists....

 

Customer: replied 3 years ago.

wonderful. I bought the switch from autozone.

it has only one wire connection.

it is not by the oil filter.

 

why won't the fuel pump stop running after I turn off the ignition?

I was told, the fuel pump is started through the switch,

through the fuel pump relay housed in the fuse box on the passenger side of the car,

i replaced the relay and the problem continued.

 

I also researched and found....after the motor begins running, the fuel pump is kept running by the oil pressure cut off switch which is wired from the relay....it is one wire leading out to the switch which is installed somewhere above the oil filter and I think I will have to remove the power steering pump in order to access it.

 

what I wanted from you was the location of this switch

and to solve the problem of the fuel pump that won't shut off when you turn the ignition off.

 

 

yet you are saying this switch does not exist. it exists on my wiring diageram in my haynes and on a diagram sent by another one of your experts.

from all my research, it is a mystery switch that exists....

 

Expert:  Jay replied 3 years ago.
Is this a US model Pathfinder?

Let me know, thanks Jay!

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