Toyota 5FGC25 Ser# 14231 was manufactured Jan 15, 1990

Thanks Bruce The serial # is 14231

If you are interested on how the 5FG system works, it as follows:
-From hydaulic tank to pump, to lift /lower, tilt combination valve, with built-in in flow control (flow divider, 3.33 GPM mininum to steering/brake criciut). From flow control valve to brake booster (with internal flow divider to steering, I am unable to determine which has priority brakes or steering). The brake control valve has 4 connection: input from pump, to brakes (711 psi max for 2 ton and 996 max for 3 ton), to power steering and bleed off from brakes when the brake peddle is released. The flow from the brake control valve goes to the steering control valve then back to the hydraulic tank.

Checking out the pump:
Spec. 10 GPM at 1500 rpm (am not sure if pump speed or engine speed).
-Connect flow meter (in pump output) and check flow, Operate tilt to deadhead, keep engine is at same rpm, if flow seriously drops ( to to less than 7 gpm) pump is worn out.
- If you do not have a flow meter, the problem is more apparent at low engine rpms. Undo the plate that is on top of the hydraulic tank and disconnect the return hose from the control valve to this plate, connect a short length of pipe to the control valve return line and stick the other end in the gap between the plate and hydraulic tank so that you can see the oil flowing back from the control valve. Dead head the tilt and if you see a major drop in flow and the engine not loading up good sign that the pump is worn out. Also check the bottom of the tank for metal filings and the pump suction strainer.
Note: There is a return line to the hydraulic tank from the brake booster, oil should only flow when the brake peddle is released and only enough oil to drain the brake cylinders. If oil is flowing when the peddle is pressed then the brake booster is the problem.
I may be wrong but I think this machine was manufactured late 80s or early 90s, give me the serial number if you want the date of manufacture.
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Keep in mind this unit is 34 years old (old enough to retire from the UAW auto plants)- parts will continue to be a problem in getting due to age and if available will be quite expensive and the unit will continue to have breakdowns. Consider finding a new used unit like only 15 years old. Most scrap yards will give you $350 to 500 for the unit due to the increase in steel prices - all fluids & batteries need to be removed.

Forklifts are like good wiskey they don't get better with age.

Hi Bruce deadheaded the tilt with the brake on steering did not
want to work revved it up to around 1500 and the steering started to loosen up what do you think replace the pump

Added note
deadhead the tilt and keep the engine arround 1000 rpm. Operate the steering and the brake. If this improve the steering, the priorty may be the problem. If running the engine at 1500 rpm improve the steering when the brake is applied suppect worn pump or suction leak. If you have a flow meter it is the best way to check for worn pump and priority valves.

I will check the service manual and see if I can come up with a answer. Try to reply tomorrow night.

thanks Bruce I checked it doesnt stall when deadheading the steering but when you are coming up to a corner to put a load away the steering almost locks up if you take your foot off the brake it returns to normal tried a two foot stop increase rpm when aplying brake steering still locks up

The brakes on this machine are powered by the hydraulic system (CHIP Brakes) after the flow divider to the power steering. Make sure the fuel mixtures and timing are correct. There is a vacuum diaphram that boost the throttle when the engine vacuum drops due to engine loading. To test it the engine should not stall when the steering is deadheaded. If the operator of this machine wishes to operate the steering when the machine is stopped he should use the inching peddle to stop then release the pedded enough to reduce engine load that is appling the brakes then operate the steering.