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Electrical / Re: 87 R10 dual tank pump issue and hot fuel module
« Last post by Captkaos on Today at 08:58:36 am »The Oil pressure sending unit is a backup system to the Fuel pump relay. Fuel Pump Power through this switch is also cut if the engine stops running as the oil pressure will drop.
This is a good post by Hatzie on the operation of the 87-91 pump dual tank setup: http://forum.73-87chevytrucks.com/smforum/index.php?topic=37007.msg310663#msg310663
So are you sending switched voltage to the tan/white wire, which is turning the pump on in Start and Run? AND the Oil Pressure Switch? (note this will keep a pump running all the time)
If wired correctly the switch should divert the power from left to right. (see link above)
Technically you could run switched power down the "test" lead also and achieve the same, but I would use it to Test the pump with isolated power.
Have you checked the wiring after the switch to see if you are getting alternating power Left or Right when the switch is changed?
(I forgot to hit post yesterday, sorry)
This is a good post by Hatzie on the operation of the 87-91 pump dual tank setup: http://forum.73-87chevytrucks.com/smforum/index.php?topic=37007.msg310663#msg310663
So are you sending switched voltage to the tan/white wire, which is turning the pump on in Start and Run? AND the Oil Pressure Switch? (note this will keep a pump running all the time)
If wired correctly the switch should divert the power from left to right. (see link above)
Technically you could run switched power down the "test" lead also and achieve the same, but I would use it to Test the pump with isolated power.
Have you checked the wiring after the switch to see if you are getting alternating power Left or Right when the switch is changed?
(I forgot to hit post yesterday, sorry)

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