i have a 1991 for e-350 van, it has a 7.3l motor. i am having some problems with the glow plug circuit. when i turn the truck on the wait to start light will only come on for a second at most and then turn off, the truck is also almost impossible to start unless the block heater is hooked up for 30 or so min. I live in cali and it is not -30 degrees out side which is leading me to think that my glow plug circuit is not working or staying on. i also can hear a loud clicking noise coming from the solinoid ( or what ever the thing is called that all the glow plugs tie into mounted rite above the tranny with the plastic cover on it. it doesn't do it everytime but it does do it oftenly and it seems to click for around 10 seconds after i turn the key on and then shuts off. do you guys have any idea what could be going wrong or if you could point me in the right direction?

 

first check all the glowplugs. use a testlight hook the clamp onto pos and touch the top each glowplug (unhook the wire first)
if they all check out then proceed to see if they are getting power to them. testlight on neg and put it in the end of the female spade connector of the glow plug wire, cycle glow plugs, if no juice then go back to the relay. just cause its clicking doesnt mean its working.. all that means is the coil in it is working. one of the posts may be broken off but still in place. if that checks out your going to the controller.

 

would any of those cause the wait to start light from staying on?

 

Wait to start light will only flash if the GPs are burned out......... do you know what GPs brand are in the engine.......

If you have 2 or more bad GPs, the controller may not cycle at all.

Two problems that occur with the solid state ( 1987 to 1994 IDI engines ) GP systems. If a GP burns out ( circuit resistance goes up ), the controller cycles the GPs at a faster rate which doesn't let them get to max operating temp. If 2 or more GPs fail, the controller may not cycle the GPs at all ( very rapid or no clicking heard ). When you check the GPs, use an ohmmeter. A high resistance ( not necessarily burned out ) GP can cause circuit resistance to go up and the controller will then cycle the GPs too fast. You probably will not find this problem with a test light. Resistance spec for GPs = .5 to 1 ohm cold. Second problem. A poor controller ground ( black wire attached to valve cover stud ) will cause the controller to leave the GPs on longer, often damaging or failing them. If you are having mulitple GP failures, I would check closely the controller ground. Now the confusing part. Bad ground --> longer GP on time ( slower cycling ). Burned out GPs --> faster cycling If you have both situations, it may appear that the controller is cycling the GPs at the proper rate. Bad ground slows it up while the burned GPs speed it up ---> normal cycling. The system acts/sounds like it's working normally, but you have a hard starting concern.
By........DieselDon

Glow plug torque is 12 ft lbs, I always use antisieze on the threads.

Visit...... http://www.members.shaw.ca/k2pilot/ before removing GPs.

 

thanks for the help. i will try all of that today. any other suggestions

 

One other thing (if not mentioned) is to run a separate ground to the controller ground post. Even a slight corrosion will do weird things on the ground side. I ran a separate wire from the lug to the battery (-) side and have had great luck.

 

i dont under stand what u mean, do you want me to run another ground for the glow plugs or a wire from the battery to the glow plugs?

 

Ok - Take control box (in back of air cleaner) loose. Be carefull as this has direct connection to battery. Look inside the plastic cover for the black wire connected to one of the bolts holding down the controller to block. Attach a #10 wire from this lug (between the controller and block) and attach it to ground side of battery. This is to give the controller a great ground all the time as this spot corrodes or will come loose in time and give the controller fits.

 

Pictures help.

Look for the black ground wire, it will be under one of the mounting bolts.

The battery terminal is always hot, with two batteries the sparks will be large if you short it out when a wrench slips.

Good idea to unhook battery grounds on both batteries before you work on the glow plug relay.