Kubota pony motor question

[Bluec]

I have a 1990 ford f800 bucket truck with an asplundh boom. It has a kubota pony motor that is supposed to run the boom but when I try to run the boom and push a lever it chokes the motor down even if it is running wide open. I took it to a hydraulic shop and they told me that the pump had to produce 3500 psi to open and close the safety valves. I checked the rpm's on the pony motor and it is turning 2950 rpm's. I don't know how many rpm's it needs to be turning to produce 3500 psi. I think it may be a collapsed hydraulic hose but, not sure. I am having to run the boom off the pto and the gas is killing me. Any advice or suggestions would be greatly appreciated....thanks.

 

[Bluec]

Can anyone help me wit my pony motor problem. Any help would be greatly appreciated. Thank you!

 

[Cutter1]

Did you do a tune up on it first?

 

[Bluec]

Thank you for the advice. I pulled the spark plugs today and two of the three were in bad shape. I am going to do a oil change and tune up tomorrow and I hope that fixes the problem. Again thank you for your help.

 

[Bluec]

Changed plugs, wires, cap, oil, filter, etc. and it made no difference. Motor still runs the same and chokes down when you try and run the boom. The crazy thing is that it puts the outriggers down and will dump a full load of chips but will not run the boom. I checked all the check valves and had the two way valves on the boom checked and found nothing wrong. I don't know what else to do , so I'm taking it to a place in Kings Mountain NC tomorrow, maybe they can fix it.............

 

[Cutter1]

Do you have the engine throttled up not at idle when you run it?

 

[sawinredneck]

If the plugs were that bad, might be time for a carb cleaning, this new gas is Hell on everything and it doesn't take much to choke up a carb.
Does it surge or idle funny? Does it sound funny at full throttle?
I'd suggest cleaning the carb, fuel tank and lines then go from there.

 

[Bluec]

Do you have the engine throttled up not at idle when you run it?

Yes throttle is wide open......

 

[Bluec]

If the plugs were that bad, might be time for a carb cleaning, this new gas is Hell on everything and it doesn't take much to choke up a carb.
Does it surge or idle funny? Does it sound funny at full throttle?
I'd suggest cleaning the carb, fuel tank and lines then go from there.

I purchased a new carb and replaced the gas tank that the feeds the pony motor and replaced fuel line to pony motor. It idles fine but at full throttle it does run a little funny sometimes but not every time you run it. No change still bogs down when running the boom. Thanks for the help........

 

[Cutter1]

I have same engine on bucket and i had close to that problem.
I got luck that it stalled and would not restart.No spark tried another coil nothing.
Replace ignition pickup and its never ran better.

 

[Bluec]

I have same engine on bucket and i had close to that problem.
I got luck that it stalled and would not restart.No spark tried another coil nothing.
Replace ignition pickup and its never ran better.

Thought I was taking it to the shop yesterday but not untl next Tues. Don't know what I was thinking. I will try that tomorrow, not sure what ignition pick up is but I'll do a quick search and give that a go. Thanx for the help .........

 

[treeclimber101]

I have a 3 cylinder kubota and at a idle I can run my boom so rpms is not the problem , you have a hydro issue whether it be a pump issue or a valve body issue theres something else other than the motor going on there , I did have a problem with mine a year ago in the lower spool the when I switched from outriggers to upper controls the engine would strain and quit ....

 

[Bluec]

I have a 3 cylinder kubota and at a idle I can run my boom so rpms is not the problem , you have a hydro issue whether it be a pump issue or a valve body issue theres something else other than the motor going on there , I did have a problem with mine a year ago in the lower spool the when I switched from outriggers to upper controls the engine would strain and quit ....

I agree because when I switch from lower controls to upper it bogs a little and as soon as I push the controls up top it bogs and kills the engine. I thought it may be a collapsed line or pump problem. Taking it to the shop on tues, unless by some chance I get it fixed this weekend but not having much luck. Thank you for the help I really appreciate it......

 

[equipmentguru]

It sounds like a hydraulic issue. I recommend taking it to a place that specializes in hydraulic repair. They should have all the proper diagnostic equipment to figure it out. Sorry, but without a hydraulic schematic I can't be much help to find the cause of the problem. Good luck

 

[Bluec]

It sounds like a hydraulic issue. I recommend taking it to a place that specializes in hydraulic repair. They should have all the proper diagnostic equipment to figure it out. Sorry, but without a hydraulic schematic I can't be much help to find the cause of the problem. Good luck

Yea I agree, I've tried about everything that I'm capable of so I've got a appointment Tues. morning to hopefully get it repaired. I will definitely post the fix as soon as they get it repaired. Thank you for your help......

 

[equipmentguru]

Your welcome. If you need anymore help and can get a hold of some schematics let me know and I can help you further.

 

[2treeornot2tree]

Does it have a hydrolic tool lever? Just a thought, but could it be on. Mine bogs when its on and I try to move the boom

 

[Bluec]

Does it have a hydrolic tool lever? Just a thought, but could it be on. Mine bogs when its on and I try to move the boom

Yes it has a hydraulic tool lever and I already checked that hoping that might be the problem, but no luck. I took the truck to a shop that only works on these type of trucks and the guy told me that the motor was barley running on two cylinders. We decided to replace the motor and he guaranteed that would fix the problem.......hope he is right....thanks for the help and I will post after I pick up the truck with the final fix............

 

[Bluec]

Yes it has a hydraulic tool lever and I already checked that hoping that might be the problem, but no luck. I took the truck to a shop that only works on these type of trucks and the guy told me that the motor was barley running on two cylinders. We decided to replace the motor and he guaranteed that would fix the problem.......hope he is right....thanks for the help and I will post after I pick up the truck with the final fix............

Well its fixed, rebuilt pony motor did the job, everything works as it should. Now it's time to get to work......thanks everyone for all the help.............................