Won't start?

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New to these bobcats. I bought a 1994 743B that won't start now. It swings over & over but won't kick. When I turn the key on I don't hear anything. I believe I sould hear a click like in a buddies of mine. Any info would sure help, thanks.

 

[Tazza]

Are you getting any smoke? is the system primed?
Ok things that come to mind if your pump is primed is the fuel shut off solenoid. When you crank it should pull back and hold in place. This is about 1 1/2” diameter and pulls back a lever just below the injector pump. If it is not pulling back, you are not getting any fuel to the injectors which will give no smoke and naturally will not start.
I'd look there first and see how you go.

 

[Fishfiles]

Are you getting any smoke? is the system primed?
Ok things that come to mind if your pump is primed is the fuel shut off solenoid. When you crank it should pull back and hold in place. This is about 1 1/2” diameter and pulls back a lever just below the injector pump. If it is not pulling back, you are not getting any fuel to the injectors which will give no smoke and naturally will not start.
I'd look there first and see how you go.

I always thought all 743's where killed by a cable , do some have a kill solinoid ? sometimes I would see the kill cable housing break under the kick panel and the whole cable housing would move back and forth but not the inner cable and the arm on the engie wouldn't move -----------crack an injector tube nut loose and see if fuel is being pumped when the motor is spinning over --------maybe water in the fuel ?, fuel pick up tube ?

 

[Tazza]

I always thought all 743's where killed by a cable , do some have a kill solinoid ? sometimes I would see the kill cable housing break under the kick panel and the whole cable housing would move back and forth but not the inner cable and the arm on the engie wouldn't move -----------crack an injector tube nut loose and see if fuel is being pumped when the motor is spinning over --------maybe water in the fuel ?, fuel pick up tube ?

743's use a cable yes, but the B revision used a solenoid. I believe it was the first diesels to use a key to shut the engine down.

 

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743's use a cable yes, but the B revision used a solenoid. I believe it was the first diesels to use a key to shut the engine down.

Thanks, I futher checked it out & the shaft for the solenoid is not moving in. So I pushed it in manually & she started right up. Tried this numerous times & that seems to be the problem. So its either the solenoid or the wiring.

 

[Fishfiles]

Thanks, I futher checked it out & the shaft for the solenoid is not moving in. So I pushed it in manually & she started right up. Tried this numerous times & that seems to be the problem. So its either the solenoid or the wiring.

I worked on 743 B but can't really rememeber them well ----I would think it was like this : the first kill solinoids were wired up was like this , there is a hold coil and a pull coil built into the solinoid , the pull side pulls the linkage over to run position while the motor is spinning over by a wire to the armature terminal of the solinoid , once the motor starts and oil pressure achieved then voltage is sent to the hold coil to keep the motor running , the hold side went thru a relay ----------you didn't really say if the linkage arm will stay in run once it is moved over by it's self with the key on , this would tell you the hold side is ok , if you have voltage to the pull side the coil when the motor is spinning over and it doesn't pull the linkage then the solinoid is bad -----that was the first generation of kill solinods and they then went to a fuse and relay to pull the linkage and the newer ones ran the kill solinoid set up using a timer and a relay to pull the linkage over there is no voltage going to it because either a bad fuse , relay or wiring , some had a dioxde in the wiring harness

 

[Tazza]

I worked on 743 B but can't really rememeber them well ----I would think it was like this : the first kill solinoids were wired up was like this , there is a hold coil and a pull coil built into the solinoid , the pull side pulls the linkage over to run position while the motor is spinning over by a wire to the armature terminal of the solinoid , once the motor starts and oil pressure achieved then voltage is sent to the hold coil to keep the motor running , the hold side went thru a relay ----------you didn't really say if the linkage arm will stay in run once it is moved over by it's self with the key on , this would tell you the hold side is ok , if you have voltage to the pull side the coil when the motor is spinning over and it doesn't pull the linkage then the solinoid is bad -----that was the first generation of kill solinods and they then went to a fuse and relay to pull the linkage and the newer ones ran the kill solinoid set up using a timer and a relay to pull the linkage over there is no voltage going to it because either a bad fuse , relay or wiring , some had a dioxde in the wiring harness

It could simply be a bad solenoid, the easiest way i have found to check is to use some cables to jump it. Remove the plug, hook the black wire to -ve then use the +ve on the other 2 terminals one at a time. One should make the arm snap back, this is your pull coil. The other should just spark a little but not move the coil, this is your hold coil. Now you know what one is what hold power to the hold coil, then use another wire to touch +ve to the pull coil. It should snap back but with power to the hold coil it should stay in place and not release. If it drops your adjustment is out or the coil is bad. If the plunger does not fully seat the hold coil can't hold it in place.
Now do NOT hold power on the pull coil for long periods of time, it will burn out.
I don't know how they are wired in the 743B but the one i setup was ground, power to the accessories on the key switch went to the hold coil. Then the pull coil was wired to the starter, when the engine is cranking the pull coil is active. You never crank for long periods of time so the solenoid is safe.

 

[Deleted member 2538]

It could simply be a bad solenoid, the easiest way i have found to check is to use some cables to jump it. Remove the plug, hook the black wire to -ve then use the +ve on the other 2 terminals one at a time. One should make the arm snap back, this is your pull coil. The other should just spark a little but not move the coil, this is your hold coil. Now you know what one is what hold power to the hold coil, then use another wire to touch +ve to the pull coil. It should snap back but with power to the hold coil it should stay in place and not release. If it drops your adjustment is out or the coil is bad. If the plunger does not fully seat the hold coil can't hold it in place.
Now do NOT hold power on the pull coil for long periods of time, it will burn out.
I don't know how they are wired in the 743B but the one i setup was ground, power to the accessories on the key switch went to the hold coil. Then the pull coil was wired to the starter, when the engine is cranking the pull coil is active. You never crank for long periods of time so the solenoid is safe.

Has anyone retrofitted a solenoid onto a 743? Does it pull just like the cable or is it a fuel valve? I like the idea of just using the key...

 

[Tazza]

Has anyone retrofitted a solenoid onto a 743? Does it pull just like the cable or is it a fuel valve? I like the idea of just using the key...

Yep!! I did that to my 743. Remove the cable from the shut down arm and install a solenoid, i needed to make a mounting plate and fit a spring to it, but it works a treat. Cost about $90 AUD for the solenoid. Wired it to the starter and key switch, hasn't missed a beat. But as i said, you will need to make a plate to mount it to, they don't simply bolt on I'm afraid.

 

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Yep!! I did that to my 743. Remove the cable from the shut down arm and install a solenoid, i needed to make a mounting plate and fit a spring to it, but it works a treat. Cost about $90 AUD for the solenoid. Wired it to the starter and key switch, hasn't missed a beat. But as i said, you will need to make a plate to mount it to, they don't simply bolt on I'm afraid.

I found out something new last night. If I manually pull in the shaft of the solenoid it'll start no problem. Once it starts & warms up shutting off the engine, it starts off the key everytime. The solenoid just doesn't seem to engage when it is cold. I didn't get a chance to get indept with it yet but I will this weekend.

 

[Fishfiles]

I found out something new last night. If I manually pull in the shaft of the solenoid it'll start no problem. Once it starts & warms up shutting off the engine, it starts off the key everytime. The solenoid just doesn't seem to engage when it is cold. I didn't get a chance to get indept with it yet but I will this weekend.

Aye Mate , sounds ya solinoid's goin' on a bloomin' blink ---------- is the plastic on the end of the solinoid where the wires come out of it puffed up and out ? -----it's a good sign of it heating up and going out --------

 

[Tazza]

Aye Mate , sounds ya solinoid's goin' on a bloomin' blink ---------- is the plastic on the end of the solinoid where the wires come out of it puffed up and out ? -----it's a good sign of it heating up and going out --------

Yep, bad solenoid or bad pull coil timer.

 

[bobcat753]

Aye Mate , sounds ya solinoid's goin' on a bloomin' blink ---------- is the plastic on the end of the solinoid where the wires come out of it puffed up and out ? -----it's a good sign of it heating up and going out --------

My solinoid was puffed out on the top were the wires came out, next thing I did was order a new one. Now shes purring like a kitten!

 

[jander]

Yep!! I did that to my 743. Remove the cable from the shut down arm and install a solenoid, i needed to make a mounting plate and fit a spring to it, but it works a treat. Cost about $90 AUD for the solenoid. Wired it to the starter and key switch, hasn't missed a beat. But as i said, you will need to make a plate to mount it to, they don't simply bolt on I'm afraid.

Where is this solenoid everybody is talking about?

 

[Tazza]

Where is this solenoid everybody is talking about?

Looking from the back of the machine, on the left. It will pull a lever near the injector pump. If its fitted, you can't miss it. Its right next to and below the throttle linkage.