motor bogs then stall under full load?

[7LBSSMALLIE]

you mentioned playing with throttle. are you running at full, as unit was designed to do. you might not have an issue.

reread previous post trying to get straight in my head. are you saying, at 1/2 you can spin. at full it stalls? if this is the case it will be quite intresting, im on board ,

 

[743bobcat]

reread previous post trying to get straight in my head. are you saying, at 1/2 you can spin. at full it stalls? if this is the case it will be quite intresting, im on board ,

should clarify I run it at full throttle. what I meant was half stick. sorry

 

[7LBSSMALLIE]

reread previous post trying to get straight in my head. are you saying, at 1/2 you can spin. at full it stalls? if this is the case it will be quite intresting, im on board ,

have any of the drive lines bee replaced, could it be we are feeding more oil than can be returned, a restriction to flow would cause this sympton. would be represented by extremley hot hyd oil. the relief replenish on the 743 rarely crack open, unless good tires or tracks against an imovable object. or brake on.even than should not stall. but go over relief...is there any stick feedback(the 743 has syptom called stick waggle or feed back. this when the sticks start start feeding off themselves back and forth.ARM BREAKER IF NOT CAREFUL) any issues?

 

[743bobcat]

have any of the drive lines bee replaced, could it be we are feeding more oil than can be returned, a restriction to flow would cause this sympton. would be represented by extremley hot hyd oil. the relief replenish on the 743 rarely crack open, unless good tires or tracks against an imovable object. or brake on.even than should not stall. but go over relief...is there any stick feedback(the 743 has syptom called stick waggle or feed back. this when the sticks start start feeding off themselves back and forth.ARM BREAKER IF NOT CAREFUL) any issues?

no feedback from stick just slowly dies. I was wondering about too much oil kinda like locking things up. Almost feels like its running out of air or fuel.

 

[743bobcat]

no feedback from stick just slowly dies. I was wondering about too much oil kinda like locking things up. Almost feels like its running out of air or fuel.

parts I have replaced so far: fuel sender and lines lines all the way to injectors fuel filter hydraulic filter fuel cap ( ran without and with to see if vent problem) only part in fuel line not replaced was pump ball was wondering if that could be closing off fuel due to deterioration? someone else said maybe fuel pump timing? I've had the machine for around 9-10 yrs been living with it at half stick but not happy.

 

[Tazza]

parts I have replaced so far: fuel sender and lines lines all the way to injectors fuel filter hydraulic filter fuel cap ( ran without and with to see if vent problem) only part in fuel line not replaced was pump ball was wondering if that could be closing off fuel due to deterioration? someone else said maybe fuel pump timing? I've had the machine for around 9-10 yrs been living with it at half stick but not happy.

The primer bulb is always a possibility, but not sure.... I have heard of the internals of the fuel lines falling apart causing restrictions.
If it was me, start from scratch. Get a bottle of fuel, eliminate as many things as possible, so get a new hand primer and some new fuel hose. Run a hose from a CLEAN supply of fuel, hose in the bottle, then hand primer then straight to the lift pump, no filter. This is why you need for it to be clean and you know its clean. Start it up and see what it does, the only possible restriction here is the lift pump.
If ti still doesn't run right, get someone else to drive it and load it down, you out the back and give the primer bulb a squeeze. This will give you more fuel pressure, if the revs jump up, you have a problem with your lift pump.
Start there, it will let you know if that area is at fault or not.
The pump timing is all set with gears, it can o nly be out if someone was in there messing around...

 

[mrdeere1959]

The primer bulb is always a possibility, but not sure.... I have heard of the internals of the fuel lines falling apart causing restrictions.
If it was me, start from scratch. Get a bottle of fuel, eliminate as many things as possible, so get a new hand primer and some new fuel hose. Run a hose from a CLEAN supply of fuel, hose in the bottle, then hand primer then straight to the lift pump, no filter. This is why you need for it to be clean and you know its clean. Start it up and see what it does, the only possible restriction here is the lift pump.
If ti still doesn't run right, get someone else to drive it and load it down, you out the back and give the primer bulb a squeeze. This will give you more fuel pressure, if the revs jump up, you have a problem with your lift pump.
Start there, it will let you know if that area is at fault or not.
The pump timing is all set with gears, it can o nly be out if someone was in there messing around...

you adjust pump timing with shims

 

[Tazza]

you adjust pump timing with shims

The fine adjustment is done with shims under the pump, but the main timing is set with gears behind the front alloy cover. You have a gear on the crank, cam chaft and injector cam shaft that all must be in the right position.

 

[7LBSSMALLIE]

The fine adjustment is done with shims under the pump, but the main timing is set with gears behind the front alloy cover. You have a gear on the crank, cam chaft and injector cam shaft that all must be in the right position.

lets start again from operator perspective. is lift and tilt good? is it a drive issue if so .when does it happen. both sticks ? fwd or rev(sorry to ask but lets clarify exact symptom.) lft or right.? uphill or down hill. hot or cold.?

 

[Tazza]

lets start again from operator perspective. is lift and tilt good? is it a drive issue if so .when does it happen. both sticks ? fwd or rev(sorry to ask but lets clarify exact symptom.) lft or right.? uphill or down hill. hot or cold.?

Even smoke levels when its stalling or starts to drop off. Smoke when running at idle and flat out with no load. Smoke at startup.
I understand 7bsmallie thinking, you need to try and rule things out that is pulling the engine down. It could be the hydrostats, the hydraulics or even a lazy motor.

 

[Des]

Even smoke levels when its stalling or starts to drop off. Smoke when running at idle and flat out with no load. Smoke at startup.
I understand 7bsmallie thinking, you need to try and rule things out that is pulling the engine down. It could be the hydrostats, the hydraulics or even a lazy motor.

Replace the hand primer,I had a customer with a 443 have the same problem, I went through the fuel system and finally I replaced the hand primmer ,problem fixed.

 

[743bobcat]

Even smoke levels when its stalling or starts to drop off. Smoke when running at idle and flat out with no load. Smoke at startup.
I understand 7bsmallie thinking, you need to try and rule things out that is pulling the engine down. It could be the hydrostats, the hydraulics or even a lazy motor.

I really appreciate the help this problem! If you think it will help, I will try to video the stalling don't know if I can do it today but will tomorrow. As far as smoke I only get a little at cold start up (depends how cold and long i crank) then no smoke maybe an occasional puff. did change glow plugs due to a hard start in winter seemed to help (with the starting not the dying) Going down a hill the engine will rev? machine doesn't really go faster but engine speed increases? This is why I started thinking hydraulics? I can't really get to the fuel bulb to try to squeeze while moving it is in far next to motor and I don't have a driver I trust. stalling seems to be only with drive hydraulics. stalls in both forward and reverse. Its like going up a grade wih a standard truck and not having a throttle, if that makes sense? it will just gradually die. I just keep letting off the sticks till it "catches up" then maintain that stick position.

 

[743bobcat]

I really appreciate the help this problem! If you think it will help, I will try to video the stalling don't know if I can do it today but will tomorrow. As far as smoke I only get a little at cold start up (depends how cold and long i crank) then no smoke maybe an occasional puff. did change glow plugs due to a hard start in winter seemed to help (with the starting not the dying) Going down a hill the engine will rev? machine doesn't really go faster but engine speed increases? This is why I started thinking hydraulics? I can't really get to the fuel bulb to try to squeeze while moving it is in far next to motor and I don't have a driver I trust. stalling seems to be only with drive hydraulics. stalls in both forward and reverse. Its like going up a grade wih a standard truck and not having a throttle, if that makes sense? it will just gradually die. I just keep letting off the sticks till it "catches up" then maintain that stick position.

sorry Des I missed your response. think if I get home early tonight I will try to bypass hand pump. theres a boat store in town I wonder if they carry the pump I'll just replace it. Dealer is far from me.

 

[743bobcat]

sorry Des I missed your response. think if I get home early tonight I will try to bypass hand pump. theres a boat store in town I wonder if they carry the pump I'll just replace it. Dealer is far from me.

so today I took the fuel shut off valve out of the system and it seems much better my question is this thing looks home made does anyone know the part number for an original so I can look at it? I don't think it opens all the way I can still stall the machine so I'm going to replace fuel line from tank to shut off and all the clamps since I have it apart. my return line doesn't look like its been replaced but that shouldn't matter right?

 

[Tazza]

so today I took the fuel shut off valve out of the system and it seems much better my question is this thing looks home made does anyone know the part number for an original so I can look at it? I don't think it opens all the way I can still stall the machine so I'm going to replace fuel line from tank to shut off and all the clamps since I have it apart. my return line doesn't look like its been replaced but that shouldn't matter right?

The 743 did not come standard with a shut down solenoid. You can use a cable tie or wire to hold the shut down lever back for a test.
The return line should be ok, just use a little compressed air to make sure its clear though.

 

[743bobcat]

The 743 did not come standard with a shut down solenoid. You can use a cable tie or wire to hold the shut down lever back for a test.
The return line should be ok, just use a little compressed air to make sure its clear though.

sorry should have been clearer. meant the inline fuel valve. I think this one was home-made it also looks to be 1/4 inch line and I don't think it opens all the way. it was inbetween the tank and fire wall. my manual mentions it but no pic. local parts store has only 1/4" lawnmower stuff.

 

[skidsteer.ca]

sorry should have been clearer. meant the inline fuel valve. I think this one was home-made it also looks to be 1/4 inch line and I don't think it opens all the way. it was inbetween the tank and fire wall. my manual mentions it but no pic. local parts store has only 1/4" lawnmower stuff.

If needed, just extend the fuel pickup hose into the cab where you can operate your hand primer bulb or monitor it to see if the engine is sucking it flat from a lack of fuel flow.
Or if in doubt of your fuel lines, mount a 1 gal can on the roof and start a gravity feed to the engine and see if it runs better that way. The you will know if it is in the fuel lines.
Ken

 

[743bobcat]

If needed, just extend the fuel pickup hose into the cab where you can operate your hand primer bulb or monitor it to see if the engine is sucking it flat from a lack of fuel flow.
Or if in doubt of your fuel lines, mount a 1 gal can on the roof and start a gravity feed to the engine and see if it runs better that way. The you will know if it is in the fuel lines.
Ken

I replaced the fuel line from the tank to the primer ball and removed the shut off valve (thinking it might be restrictive) the primer seems to be working correctly compared to new ones at parts store. machine seems better but still can stall it. However I have another question and my manual isnt clear. first how do I know the rpm of the engine? I have checked my throttle stop adjustments and the lever hits both, but are they adjusted right? also the fuel line comes under the engine up to a circular junction then goes to the pump. my manual makes no reference to proper rpm or this piece? its in the pictures but no explanation. Just starting over with the problem and assuming everything is wrong and making adjustments as I go. I replaced the glow plugs a couple years ago and never replaced the last one (behind the fuel lines) is there a way to sneak it out? just figured no is the time if I'm messing with fuel. thanks kevin

 

[jerry]

I replaced the fuel line from the tank to the primer ball and removed the shut off valve (thinking it might be restrictive) the primer seems to be working correctly compared to new ones at parts store. machine seems better but still can stall it. However I have another question and my manual isnt clear. first how do I know the rpm of the engine? I have checked my throttle stop adjustments and the lever hits both, but are they adjusted right? also the fuel line comes under the engine up to a circular junction then goes to the pump. my manual makes no reference to proper rpm or this piece? its in the pictures but no explanation. Just starting over with the problem and assuming everything is wrong and making adjustments as I go. I replaced the glow plugs a couple years ago and never replaced the last one (behind the fuel lines) is there a way to sneak it out? just figured no is the time if I'm messing with fuel. thanks kevin

There are hand held non contact tachometers around maybe the dealer or a mechanical friend has one to borrow?.

 

[Tazza]

There are hand held non contact tachometers around maybe the dealer or a mechanical friend has one to borrow?.

That round part is possibly a one way valve, its not factory.
How hard do you need to push the machine before it stalls out?
As already stated, you need a tacho to know what the engine is doing, i have a cheap Ebay one that uses reflective tape and a laser beam. Just put the tape on the crank pulley, easy. The RPM should be factory set, generally does not need changing.