My 763F was running fine. I pulled to idle and stepped off for a minute and when I returned it had quit. I fooled around trying to restart without success. Eventually, I found that if I squeezed the priming bulb it would "squish" for five or six times and then get firm. After that the tractor would start and I could run it for 30 to 60 seconds. Rinse and repeat a few times and I got it back over to the shop. There are no codes set. I did notice a small amount of fuel weeping out from the pivot arm where the throttle rod attaches to the injector pump. That is something new. I replaced the tank pickup a few years ago. For this tractor, that means in the last 50 hours. I read another post with similar symptoms and the prognosis suggested the pump was bad. I assume that means the injector pump. Is there another? The service manual shows shims for timing, etc. Is that something the average mechanic wants to mess with? Or would a replacement pump use the same shim stack? Is the pump something that can be easily rebuilt with a kit or is it something that gets exchanged for a rebuild? Any suggestions are appreciated. Thanks, DC
Help Support SkidSteer Forum:
Yes you have a "lift pump" or "transfer pump" that moves fuel thru the filter and to the injection pump. Much cheaper to try the lift pump first and very easy to change. Google bobcat part # 6655216 and you will see what to look for. You can remove the pump and move the plunger with your fingers with the inlet fuel line still hooked up and see if it pumps.
As for your other question about the injection pump, it is easy to swap out with a rebuilt pump and best to just order a reman pump or have local diesel shop rebuild. In most cases the shim is reusable and make sure to not use any sealant such as silicone when installing pump.
The fact it runs while pumping the primer I would look at the fuel lines from tank to the pump maybe replace them. Only 10' of rubber hose. It is possible the lift pump is bad. I would try hooking a short hose from the pump to a fuel can and see if it works
flyerdan
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I would suspect the leaking seal on the throttle shaft, that can introduce air either from the injector pump pulling it in or leakdown when it's not running.
It might be possible to replace the seal without removing the pump, depending on how mechanically inclined you are. Providing that you can find the seal for it, which should be Kubota PN 25-15543-00 according to this breakdown.
The throttle shaft seal is an oil seal, no fuel should be in contact the throttle shaft as it is a governor control shaft and does not control fuel. I believe he was mistaken when he said fuel was coming from that seal, it usually leaks engine oil. Just a heads up
Thank you for the information. My service manual is very complete... except for the engine I now recognize. I did google the part number and recognized the pump - a HUGE help. I ordered a pump through Amazon for $35. The Bobcat dealership had it priced at $130. I replaced the pump and hoses yesterday and I have a running tractor! It took a few minutes to work all of the air but it is running smoothly now. If I place a finger over the pump inlet and stroke the actuator I feel a small vacuum with the new pump and none with the old. Thanks again for the help. DC
flyerdan
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If the lift pump was bad, you should check your engine oil and see if it's excessively high on the dip stick or smells of diesel. Often when the pump goes bad it pumps fuel right into the crankcase.
