fuel pump issues cannot locate inertia switch
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fuel pump issues cannot locate inertia switch
I am not getting power to my HP fuel pump on the frame rail. I was sent a schematic and diagram showing the location under the dash but I cannot seem to locate it 
Fleet Owner
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From: Easton,Ks
He is working on a 1989 and no it is not in the kick panel.
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Thank you all for the feedback. I have to roll with Subford and say that is is supposed to be on the driver's side above the clutch pedal. I found what appears to be the remnants of an inertia switch but as it would be, the plug has been disconnected and there is a paper clip stuck in the plug to jump it out or bypass it.(which was tucked up above a wiring harness so I could not see it readily) Strangely, I am not getting 12 volts there either. I figure I should have been able to read 12 volts to ground off of the paper clip jumper...But I don't.... I had to stop for a bite to eat (hunger/frustration headache) I am heading back out to trace it back from there 
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From: ohio
Check your relays and thier connectors,The connectors are prone for failure. If i remember correctly the ecm relay powers the fuel pump relay. Does your check engine light come on with the key in the run position?
Fleet Owner
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From: Easton,Ks
Check the wires under the relays, that is a problem spot on your truck.
The EEC (ECM) Power relay does send power to the coil of the Fuel pump relay when the key is turned on.
The Computer will then ground the other side of the fuel pump relays coil to close its contacts. The computer will ground this fuel pump relay for one second when the key is turned on and then again when the engine is cranking or running. To bypass the computer just ground pin #6 of the EEC self-test plug and turn on the key.
The power for the fuel pump relays contact common comes from a fuse link at the starter solenoid battery side. The output contact goes to the inertia switch.
The EEC (ECM) Power relay does send power to the coil of the Fuel pump relay when the key is turned on.
The Computer will then ground the other side of the fuel pump relays coil to close its contacts. The computer will ground this fuel pump relay for one second when the key is turned on and then again when the engine is cranking or running. To bypass the computer just ground pin #6 of the EEC self-test plug and turn on the key.
The power for the fuel pump relays contact common comes from a fuse link at the starter solenoid battery side. The output contact goes to the inertia switch.
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I have replaced both the ecm relay and the fuel pump relay. The check engine light does indeed come on with the key in the run position. Sadly, the check engine light is on all the time ever since I let a local garage work on my rig. They claim that it is due to a loose wire on the distributor???????Anyway....... I just checked for continuity from the inertia switch down to the HP fuel pump plug. Everything seems to be OK. I still do not have 12 volts at the inertia switch???? I think I either have a bad ground somewhere or my problem lies between the fuel pump relay and the inertia switch. Going back to have another whack at it!!!!!!Any and all suggestions are welcome. Thanks to all!!!!!!
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From: Easton,Ks
If you also had the key on did the fuel pump relay click when you ground pin #6 with the key on?
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Hey Subford,
I am almost certain that it was clicking whenI grounded the test plug. Initially I was trying to see if their was 12 volts there and I kept hearing the relay chattering while I had my 12 volt tested on it. Every time I touched the tester to the back of the socket I heard the clicking and I thought it was strange that it was happening withthe tester but as long
as there is a good fillament in ther bulb, it makes the circuit I guess...
I am almost certain that it was clicking whenI grounded the test plug. Initially I was trying to see if their was 12 volts there and I kept hearing the relay chattering while I had my 12 volt tested on it. Every time I touched the tester to the back of the socket I heard the clicking and I thought it was strange that it was happening withthe tester but as long
as there is a good fillament in ther bulb, it makes the circuit I guess...