98 Gt Fuel Pump Question

wmburns said:

The 98 model year uses a two speed fuel pump with a ballast resister and speed control relay to change between high and low speeds. For the 98 model year it would be normal to see less than 12 volts at the IFS switch IF the fuel pump speed relay is in low speed mode.

IF you are testing key on 12 volts at the trunk IFS switch THEN that does mean that the CCRM is likely good.

Note. For the 98 and older Mustangs there aren't any active components between the IFS switch and the fuel pump. So if seeing 12 volts at the IFS switch and less at the fuel pump harness, this means:

• The IFS switch maybe bad
• There is a weak electrical connection in the wiring harness.
• the fuel pump ground is bad/weak.
• at the time the reading was taken the fuel pump was in the low speed mode. If true then 7 volts would be a reasonable reading.

If you never hear the fuel pump at run at initial key on AND the IFS switch has voltage, THEN the odds favor a bad fuel pump.

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