Bobcat S650 W/Kubota Dies under Load..

I have a Bobcat S650 with a Kubota Diesel, if I take the boom all the way down and then deadhead it (keep going) engine will bog down and die. Basically any function I do in this sense, where the fluid should bypass, the motor will bog and die (tilt included). I can use it, but it seems lower on power. It starts right up, revs up high, and lifts anything you pickup, so it’s functional, but it’s operating like a 50HP machine in a 75hp machines body. The motor only has 1600 hours. If I rev the engine up to 1800 rpm and then curl the bucket back and deadhead cylinders, still will bog it down and die. What I’ve done: new primer bulb, new fuel pump, and removed the fuel line from pickup in tank, and sucked fuel straight from a diesel jug to take a cracked pickup out of equation. I also replaced shutoff selenoid with a new OEM one incase plunger was failing. New fuel filter as well. Nothing helped. I’ve seen these run for 10k plus hours easy, I’m at a loss. Air filter is new also. Any ideas would be appreciated. Thank you!

The speed sensor on the fly wheel housing is critical on those. My first check would be cleaning the metal filings from it and re-adjusting it to spec.

Everything I know about it is it’s more timing related and would set off a code if it’s out of spec. I have concerns about removing it and not getting it back to spec. My research has shown that this won’t affect power like it is. Not saying you’re wrong tho!

It has to have an open or shorted circuit to make a code. It’s a dumb, analog two wire mag sensor. I’m not a Bobcat guy, but spent a lot of time purchasing and working on them. Screw the sensor in until they contact the flywheel teeth and back off a 1/2 turn. Just sayin’, check the easy stuff first. I’m not convinced the fuel pickup inside the fuel tank is good. Those are notorious. We have threads on that topic.

I will check that sensor. The fuel pickup can’t be an issue as I sucked fuel right from a diesel jug, essentially bypassing pickup. Still acted the same. Thank you

I purchased a new OEM sensor from the dealer. Gapped to spec with no change. Also, the problem is low power in general, there’s no blowby and the reman motor only has 1600 hours on it, is it possible the mechanical pump screws weren’t set properly to feed more fuel under heavy load? It doesn’t just have issues dead-heading. It also just dogs in power when brush hogging in the woods etc. Thank you

Might want to I’d engine. Generic search V3307 and somethings maybe t, di Also indicates a very high pressure fuel delivery system. Inspect old fuel filter? Maybe another less obvious filter or screen somewhere in fuel system. Water separator. Fuel tank drain? Water there is not good. Coal dust> not if but when on the pickup. What comes out of exhaust when it misbehaves and dies? The whole air intake system should be checked. Leaks lead to dusting and low power.

The engine is a kubota v3307-DI-T I completely bypassed existing fuel system and put an electric inline pump fed from a diesel jug straight to injection pump. It did not help and still bogs when I dead head tilt. I then started looking into turbo, pulled off intake tube and felt the wheel, solid with no play. Only 1700 hours on turbo and engine. Idk where to go from here. The motor is doggy, nothing appears to leak, filters are new or clean, and fuel pressure to pump is excellent. No smoke or hard starting.

My thoughts are that you need to confirm that the hydraulics are within spec and that a pressure relief valve isn't causing your problem before fixing what ain't broke.

Maybe it’s not an engine problem, at this point. Starting to sound like a hydraulic issue.