Ford Ranger, P0304 injector code

When 1 of our techs pulled a code P0304 on a ’99 Ford Ranger, he had the right idea by replacing a bad #4 Fuel Injector  with a new one. But when that didn’t fix it, he was able to uncovere a small detail that was overlooked and put this Ranger back into active duty.

After learning that the vehicle had a 3.0L flexible fuel engine, we saw that the new injector was for a 3.0L gasoline engine which caused the lean condition on cylinder #4. With the correct injector installed, our tech was able to make the necessary steps to correct the problem.

VEHICLE: 1999 Ford Ranger XLT 3.0L, V6, MFI, OHV, VIN V, Eng Desg -

MILEAGE: 169000

Customer Concern: The Malfunction Indicator Lamp (MIL) keeps coming on with a trouble code P0304 in memory. It has a new #4 Fuel Injector , a new spark plug, spark plug wire, and also tried a new coil pack. Swapped the spark plug and spark plug wire with other cylinders and the trouble code stayed the same. Cranking compression is 150 PSI, the same as the other cylinders.

Tests:

1. Since this is a flexible fuel engine, verify that the Fuel Injector  that was installed is the correct injector for a flexible fuel engine. An injector for a regular 3.0L engine will not deliver as much fuel as the correct injector, and will cause a lean condition on cylinder #4. If in doubt, swap the injector to another cylinder, and see if the miss follows.



Potential Causes: Incorrect Fuel Injector

Confirmed Fix: Installed Fuel Injector(s)
P0304