Question about oil pressure sender..
Posted: Sun Jun 13, 2010 4:49 pm
I have been having some fuel issues, so I was looking thru the old haynes manual.. According to the schematics in there, for "1994 and newer" engines, the fuel pump relay provides power to the pump as expected, but the oil pressure sender also contains a switch that closes above 4psi and provides "backup" power to the pump so u don't get stuck in the event the relay flakes out.. It shows that there should be a tan/white for pressure guage, orange 12v in from ECM-b fuse, and a grey out to the fuel pump, common with the grey off pin30 of the relay.. As a test it is said that if you pull the fuel pump relay out while engine is running, it will not shut off due to this backup circuit. If it does then the switch is bad.. (this info came from the Internet, as the haynes fails to EVER mention the existance of this device other than the schematic and a caption for a pic under "checking the water temp sender", for those looking, I found it near the base of the distributor!) when I pulled the relay, the engine shut off.. So I went and bought a new one from advance auto. The one they show for my 99 looked like the pic, and sure enough, had three pins in it.
Now, the one in the van has only one pin as does the harness, the tan/white for the pressure guage. This tells me that there is no switch in there on a 99 AWD..
So now for my question.. Does anyone know what year (obviously somewhere between 94 and 99..) they stopped doing the backup circuit and why? It seems like a good idea, at least to someone like me that just had a fuelpump relay go bad on my jeep and now no fuel to the van in the same week.. While my common sense (and wallet) say to return the unused piece, my brain screams "it's just two wires and a simple circuit!! Then u can have the backup!"... But there must have been a reason to dump it.. And it can't be just the cost of the two short cables..
Now, the one in the van has only one pin as does the harness, the tan/white for the pressure guage. This tells me that there is no switch in there on a 99 AWD..
So now for my question.. Does anyone know what year (obviously somewhere between 94 and 99..) they stopped doing the backup circuit and why? It seems like a good idea, at least to someone like me that just had a fuelpump relay go bad on my jeep and now no fuel to the van in the same week.. While my common sense (and wallet) say to return the unused piece, my brain screams "it's just two wires and a simple circuit!! Then u can have the backup!"... But there must have been a reason to dump it.. And it can't be just the cost of the two short cables..