743B won't start

[sahmwh]

All, It was cold yesterday when I attempted to start my 743b ('92, 3000 hours). When I first tried it, it turned over and even started and ran rough for about 5 secs before stopping. But then the battery got weak and wouldn't turn it over. I then tried jumping it from my truck ... it turned over some (although very slowly) but never ran. I disconnected the jumper cables and used a battery charger in "start-boost" mode. Now, nothing happens. I measure the voltage on the battery and was getting 12-13 volts. I noticed then that when I would turn the started key to the left (to warm the glowplugs)I could hear a faint click like a relay kicking in and then another faint click like the relay letting go. And when I turned the key to the right when I normally hear a distinct click, nothing happened (completely silent) ... needless to say, the engine never turned over. Isn't there a relay (or two) in the starter circuitry ... could that have gone bad ? If anyone can help, I would appreciate it (my cows are getting hungry). Thanks, Roger

 

[mrfixitpaul]

There should be 2 relays or solenoids in the engine compartment. 1 is for the glow plugs, the other is for the starter. A quick test to make sure the starter has not failed is to use a jumper wire and jump from the big terminal on the starter to the small terminal on the starter that has a wire connected to it...as long as there is power getting to the starter and a good ground the starter should crank. When in the 'start' position the key should activate the starter relay which in turn activates the glow plugs. If you are hearing no click check for power getting from the key switch to the relay in the start key position....I think it's a white wire but not sure.

 

[sahmwh]

There should be 2 relays or solenoids in the engine compartment. 1 is for the glow plugs, the other is for the starter. A quick test to make sure the starter has not failed is to use a jumper wire and jump from the big terminal on the starter to the small terminal on the starter that has a wire connected to it...as long as there is power getting to the starter and a good ground the starter should crank. When in the 'start' position the key should activate the starter relay which in turn activates the glow plugs. If you are hearing no click check for power getting from the key switch to the relay in the start key position....I think it's a white wire but not sure.

Thanks for the info "mrfixitpaul", I was busy doing some other stuff today, but did stop by the skid steer to hit the key just to see what would happen. I turned the key to the left to warm the glow-plugs and heard a buzzing sound ... never heard that before ... could it be the relay ? I then turned the key to the right into the "run" position and heard a very faint click. I know this sounds like the battery is weak, but Monday when I had a charger in "boost" mode on the battery, nothing, not even the buzz could be heard. Are there any instructions on how/where to check voltages etc. on these things, Thanks for any help, Roger

 

[Tazza]

Thanks for the info "mrfixitpaul", I was busy doing some other stuff today, but did stop by the skid steer to hit the key just to see what would happen. I turned the key to the left to warm the glow-plugs and heard a buzzing sound ... never heard that before ... could it be the relay ? I then turned the key to the right into the "run" position and heard a very faint click. I know this sounds like the battery is weak, but Monday when I had a charger in "boost" mode on the battery, nothing, not even the buzz could be heard. Are there any instructions on how/where to check voltages etc. on these things, Thanks for any help, Roger

A dead battery can read 12v without a load, but drop right down as soon as power is drawn from it by the glow plugs or starter. Jumping it from your truck is a good idea, if it cranks with the extra battery, your battery in the machine is dead.
As it ran and stopped, it could be gelled fuel if its cold. Open the bleed screw, squeeze the ptimer bulb till you feel its firm and no bubbles. If you can hear and feel bubbles, you are our of fuel, or have a cracked pickup tube.

 

[skidsteer.ca]

A dead battery can read 12v without a load, but drop right down as soon as power is drawn from it by the glow plugs or starter. Jumping it from your truck is a good idea, if it cranks with the extra battery, your battery in the machine is dead.
As it ran and stopped, it could be gelled fuel if its cold. Open the bleed screw, squeeze the ptimer bulb till you feel its firm and no bubbles. If you can hear and feel bubbles, you are our of fuel, or have a cracked pickup tube.

Also if your boaster cables are not the size of welding cables, they may not transfer enough amperage to crank the engine well. Did you let the truck charge the battery for 5 to 10 minutes before you tried cranking.
Ken