Hi guys In the company i work we have an automatic Toyota 7fd25 diesel forklift that wont move for at least five minutes when first started. As soon as it starts moving it runs fine all Day. If it is shut down and restarted within few minutes, it wont run again for two minutes, then runs fine again. Seems like a hydraulic pump issue, maybe not enough flow to fill the torque converter? Any ideas?
Pump possibly sucking air, pump worn or damaged internally, foreign debris in a control valve. The normal checks would be removing and checking the filter for debris, looking for leaks on the suction side of the pump (maybe a loose hose clamp or oily hose), remove and clean any suction strainers and finally plumbing a gauge into the circuits and checking pressures. Good Luck!