I have a 1986 ford f-250 6.9L diesel. After replacing my batteries, I have come to the conclusion that my glow plugs, or the sensor is bad. The manual I have doesn't explain how to preform a test to check the glow plugs. I am pretty sure the sensor is good because it was just replaced about 1-2 years ago so i dont think that plays a role in my problem. I dont think its the relay, because it clicks, and sounds like it goes through its cycle, once the key is turned on. Once i do get it started it runs strong . Maybe some one could give me some insight about this problem and maybe a testing procedure...

thanks
diesel

 

I've checked glow plugs in different diesel engines by disconnecting the wires from the glow plug and hooking a test light to them. Hook the clip from your test light to the positive side of your battery and touch the light to the terminal on the glow plug. If it lights the glow plug is not totally burned out. But it could still be shorted. You can also take a ohm meter and check the resistance from the glow plug to ground.

 

I don't even think that the Cummins has glow plugs.

 

I would take a wire off the glow plug or just put a test light on the wire going to the glow plug and have somebody hit the key. If it lights for a moment u got the power, test a couple or all of them to make sure u have no broken wires. Then take an ohm meter and go from the place on top of the glow plug to the block to see if u have continuity, maybe even get a new glow plug and check the continuity on that so u know how a good one is. If u got to take em out be careful, don't just raunch on them take your time and work em. Unhook the wires before u test the continuity.