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Old 02-27-2012, 06:59 PM   #6
olopezm
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Re: No Power To Fuel Pump, 2000 Windstar

To test the switch you should measure resistance across it's two terminals.

I guess your's is a digital multimeter. Set it at the resistance (Ω) lowest range and put each probe on each of the terminals on the switch (it doesn't matters which one) and you should see 0 ohms (it's an ideal value) but normally you'll see any value from 0 to 5 ohms (Ω). If that is the case then the switch is OK. If all you get is a dash (-) or a '1', it means the resistance is higher than the scale selected you can try going up one range until you get an actual value. In case you're already at the highest range and you still can't get a reading it means you have an open circuit (or high impedance) and the switch is not making contact (in other words it's defective). Make sure the spots you use for the probes are clean and unpainted as this can cause an incorrect reading. Some multimeters have a "continuity" tester (beeping function) which works the same way but I like to use resistance because some times the beeping function is a little slow to respond (it depends on the brand).


Try pushing harder on the switch while you test to make sure the switch is defective or it's dirty.

You say the pump ran after you bypassed the switch with the piece of wire. How thick it was? If you used a very small wire it might not be able to provide enough current to the fuel pump, which at the same time causes a drop in voltage) and that's why you're seeing a low voltage at the connector. Low voltage at the pump will make it turn slower and won't provide enough pressure to start the engine; try using a thicker wire.

Oscar.
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