glow plug controller?

[Burbanaz]

I have a friends truck that im going to work on that has a list of crap wrong with it. One thing is that he cant start it in the mornings if its below like 50 degrees without leaving it plugged in. The glow plug light comes on but im thinking maybe the controller is bad and isnt actually cycling the glow plugs since if its plugged in he can start it, it will start fine during the day as long as it hasnt been sitting too long and cooled back if its cold. What do u guys think? This is in an 89 i think f250 with the 7.3idi

 

[ak diesel driver]

I'd lean more towards the plugs myself.

 

[Burbanaz]

i was thinking that too but how many of the plugs would have to be out for it not to start?

 

[THEFERMANATOR]

Since you say it's an 89, then the glow plug controller is working if the light comes on. How long does it come on for? If it comes on for a long time then most likely it has a few burned out glow plugs. BE CAREFUL ON THE GLOW PLUGS WITH THIS ENGINE! And ONLY use BERU glow plugs in it(MOTORCRAFT from AUTOZONE is BERU plugs). Autolites are JUNK and are well known to swell and break off in the head. Also this is a 6 volt glow plug system, not a 12. that big winding on top of teh controller is a resistor to step it down to 6 volts. Once a glow plug burns out the controller makes the glow plugs stay on longer and they get more voltage which also leads to them popping and breaking off. And the 7.3's that I have dealt with all eat inejctors worse than a 6.5 does, and this leads to poor starting.