Only starts when lifting bucket 743

[Hotrod1830]

Didnt realize it had a mechanical injector pump shutoff.
How confident are you that the auxillary hyros are not engaged? If you move the right joystick left/right does it move? If you force it all the way to the right you should feel a detent and it should lock to that position. If it does move left/right and you cant get it to lock, it could be the spool valve linkage worn or binding, or valve itself has failed. easiest way I know of to test is to use a pressure gauge on quick coupler fittings and see if they have pressure on the auxilllary ports when cranking. There should be zero. That or "loop" the auxillary hydro's with fittings and a short piece of hose.

 

[Hotrod1830]

Guess I should add, if you cant get the right joystick to move to the left/right and force it all the way to far right and lock, these machines originally had a bolt that locked the lever. Even if the locking bolt is still in place, you will still need to verify the auxillary hyros are not engaged. worn, rusted or bent linkage can do funny things,

 

[repalmieri]

Didnt realize it had a mechanical injector pump shutoff.
How confident are you that the auxillary hyros are not engaged? If you move the right joystick left/right does it move? If you force it all the way to the right you should feel a detent and it should lock to that position. If it does move left/right and you cant get it to lock, it could be the spool valve linkage worn or binding, or valve itself has failed. easiest way I know of to test is to use a pressure gauge on quick coupler fittings and see if they have pressure on the auxilllary ports when cranking. There should be zero. That or "loop" the auxillary hydro's with fittings and a short piece of hose.

I will test that. Does anybody happen to know what is happening when your running the machine at half throttle and you over stress the bucket and it causes the engine to drag then stall?
This is what is seems is happening but at lower rpm. I was on a newer bobcat yesterday and did this exactly.

 

[Wayne440]

...Does anybody happen to know what is happening when your running the machine at half throttle and you over stress the bucket and it causes the engine to drag then stall?...

When "you over stress the bucket" (I assume you mean you tried to lift too much or dead ended it at one of the stops), one of these things will happen (1) the hydraulic relief valve will operate, (2) the engine will stall, (3) a hose will develop a new leak. At half throttle, you probably did not have enough engine power to do 1 or 3.

 

[repalmieri]

When "you over stress the bucket" (I assume you mean you tried to lift too much or dead ended it at one of the stops), one of these things will happen (1) the hydraulic relief valve will operate, (2) the engine will stall, (3) a hose will develop a new leak. At half throttle, you probably did not have enough engine power to do 1 or 3.

ok because i'm guessing this is what's happening with my loader.
just att very low rpm
thanks

 

[Hotrod1830]

Maxing out the bucket hydraulics or "dead heading" them should not stall the engine. The relief valve is there for that exact reason. If your operating the bucket AND hydro's at full tilt at the same time, that may stall the engine, but bucket controls alone should not stall the engine.

 

[Hotrod1830]

Just to be clear, The above applies to a properly running engine. Hydraulic load can prevent and engine from cranking fast enough to start.
A engine that is NOT running properly can be stalled by use of the bucket hydraulics.

 

[repalmieri]

I was told by someone that the shaft that the motor connects to(PUMP?) is supposed to spin easily like an alternator. Is this true? I was'nt able to spin with my hand at all.

 

[oiu789]

If I remember right there is a neutral start unloading valve in the hyd pluming that unloads the hyd pump when starting the unit. Get the hyd diagram to see if there is one.

 

[repalmieri]

If I remember right there is a neutral start unloading valve in the hyd pluming that unloads the hyd pump when starting the unit. Get the hyd diagram to see if there is one.

Thanks I will give it a look today and report back......