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fuel pump or...?


bumpy
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I suck at electrical stuff, but here's what I do. First, determine which is the "control" side and which is the "supply" side. Terminals 85/86 should be the control voltage, and 87/87a are the switched posts on the supply side (which provide power to the accessory). Terminal 30 is the hot lead from the power source that gets switched to either 87 or 87a when the 85/86 circuit is energized. To test to see if the relay is switching on the control voltage, ground pin 86 and apply 12V to 85....you should hear the relay click. With no power to 85/86 there should be continuity between pin 30 and 87, and with power it should be open and there should be continuity between 30 and 87a.

 

Of course, the relay could be working fine when tested but be weak internally and fail intermittently under load, which is kind of impossible to test for:( I had a weak AC relay in my other car and chased it (even took it to a garage) for a couple weeks until one day the AC cut out when running and I smacked it (hard)...and it worked again for about a minute.

 

I'm sure more electronically-inclined members have better methods and can give more advice than me on relays....like I said, it's not my strongest subject. That and bodywork......

 

FWIW, the ECU provides a completed ground for the fuel pump relay, so it could be a break in the wiring between the relay and the ECU also. You can bypass the relay to check the fuel pump by jumping two pins on the small diagnostic test port on the passenger fender between the blower motor and the coil. (pins 5 and 6)

 

Jeff

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