825 Bobcat lugs down going up hill

825 Bobcat hydrostatic. all new fluids, filters, rebuilt perkins(pistons,rings,pins,bearings,injection pump, injectors). 60" smooth bucket, 4 rebuilt cylinders. no leaks anywhere. Hi/Lo speed both work. Runs good on flat ground, lift and bucket both work OK. Start up a hill and the motor bogs down. go up it real slow and it will go but try to accelerate and it bogs again. even with wide open throttle the same thing happens. what is happening? what should I check? thx for looking.

Try filling the fuel tank to tippy top and try it if better might be a cracked pick up tube in the fuel tank

antfarmer2 said:

Try filling the fuel tank to tippy top and try it if better might be a cracked pick up tube in the fuel tank

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Maybe a pluged vent in the fuel cap try looseing it........does it have case drain filters if so clean or replace

antfarmer2 said:

Maybe a pluged vent in the fuel cap try looseing it........does it have case drain filters if so clean or replace

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If it has a bleeder valve make sure it is closed

antfarmer2 said:

If it has a bleeder valve make sure it is closed

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Or sucking air from a loose or cracked fuel line or did not bleed all the air from the fuel filter mine has a plug on the top of it for this

antfarmer2 said:

Or sucking air from a loose or cracked fuel line or did not bleed all the air from the fuel filter mine has a plug on the top of it for this

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When you are on level ground and really work it, such as digging into a pile, can you hear the governor open up? It should try to keep the rpms up, I know nothing about that engine timing but if it were gas I would guess the timing is off.

jerry said:

When you are on level ground and really work it, such as digging into a pile, can you hear the governor open up? It should try to keep the rpms up, I know nothing about that engine timing but if it were gas I would guess the timing is off.

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Another good call Jerry

I know you said you changed all filters, but it almost sounds like a fuel filter issue.

reaperman said:

I know you said you changed all filters, but it almost sounds like a fuel filter issue.

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Another thought, when was the last time the hydraulic cap/breather was changed. A plugged cap will bring on the symptoms you are having. Try running without the cap on for a little while.