Troubleshooting Thermostart

[IndianaBill]

Does anyone have any troubleshooting experience on the Thermostart system? The Thermostart on my John Deere 750 is not functioning and with winter coming on I would like to get it working.

Specifically, is there any noticeable effect when Thermostart functions - smoke, noise, heat?

What controls the flow of fuel to the glowplug? When I remove the hose at the glowplug I get a single small drop. Is this expected?

What is the function of the tank? Clearly it is more than just a T in the injector return line.

I have checked the electrical connections. Battery voltage at the glowplug when the switch is turned left. Glowplug resistance to ground is one Ohm. Seems about right to me.

Thanks for any help you can provide.

 

[California]

</font><font color="blue" class="small">( When I remove the hose at the glowplug I get a single small drop. ... is there any noticeable effect when Thermostart functions - smoke, noise, heat? )</font>

The line from that little diesel reservoir may be plugged. It should drain the reservoir in a few seconds when disconected.

The Thermostart is both a heater like an automotive cigarette lighter, and an electric fuel valve.

Looking into the intake you should see the Thermostart glow after 10 seconds. Then there is a little burp as diesel is allowed in. After a moment that fuel makes a tiny flame.

 

[gbirky]

First, as the previous post indicated, it sounds like the fuel is not flowing properly from the reservoir to the plug. I have tested thermo starts by removing from the intake manifold, with the reservoir attached. I used a battery and jumper cables.

It is probably alot saver, easier, and faster to just test it on the engine by removing the hose from the air filter to the intake manifold (or the filter depending on model) from the manifold so you can see into the manifold. You can just run a jumper from the positive battery terminal to the screw terminal on the TS plug (so you don't have to turn the key). Then you can just watch to see what happens.