In the F4A-EL & GF4A-EL transmissions, when pump volume is too low, it causes low line pressure, which results in a 2-3 shift flare. Frequently these problems can be traced back to the pump's inability to flow oil to the pressure regulator. All pump volume flows through the spool valve to the regulator in the valve body. This spool valve position determines pump volume by overcoming the spring and exhausting output to suction. Sonnax has developed a pump rebuild kit K74878 for the F4A-EL & GF4A-EL pumps.
Fits 1-pan style unit and 2-pan, 7-solenoid style units with gear pumps.