Ok so I bought this 1996 f350 that was a plow truck in Vermont. it runs great! it will start great in like 45 degree weather but if it gets below like 35 it don't start. I was reading and some people where saying it could be the glow plug relay. so I bought a relay installed it. the next morning I tried to start it. I let the glow plugs just cycle ones since it was just like 35. didn't go, it just turned over and over. so I tried it again but this time let in cycle 2 times, same thing happened. so I let it cycle 5 times and it finally got going! so any ideas what it could be? is it just electrical or is it the glow plugs? any ideas are great!

 

Have you ohmed out the glow plugs?

 

no I haven't. powers coming in on the hot side and not transferring over to the post that sends power over to the glow plugs.

 

Check the voltage drop across the relay with it engaged. Need to check the valve cover connections for burned pins

 

I checked the voltage drop and It was bad. But I will check the pins also

 

You could still have gp bad.check all 8 outside end pins resistance to ground .looking for one ohm.

 

Ok will do!

 

I assume you are using #1 fuel right? Something that helped me out too, Diesel 911, its a bit expensive, but put a bit in your fuel bowl, and put some in your tank. your fuel could be gelled up!
Edit: Did you plug the truck in?

 

Yes I buy it from a very popular place, that my friend also buys his from and he isn't having this problem. I haven't tried plugging it in. I'm positive it's not fuel related! Because ones it starts it runs great!!

 

Ok the consent hot post has power same with the two smaller wires that bolt on to the glow plug relay. But the other big post don't have power when I turn the key.

 

I would try plugging it in, if it starts, then you could probably figure your glow plugs need taken out and looked at/replaced, since they aren't heating up the combustion chamber. Wind chill has a big factor too.

Based on your first post though, you would experience some rougher than normal idle, thicker smoke, at least until the truck warms up if you had bad GP's.

How long does your GPR stay on for when you first go to start the truck up in the morning?

Here is a picture comparison between the old and new glow plugs. This was a big factor in my cold starting issues. I also replaced the relay just in case.

 

Trace the wire. Color? Description.

 

Use a screwdriver to short across the two large terminals on the glow plug relay for about 30 seconds (60 if its really cold) and then try to start. If it does then your relay is bad. They have been known to be bad out of the box. If it still doesn't start then you probably need new glow plugs. Try using this as a guide: https://docs.google.com/file/d/0Byb4...VGc/edit?pli=1


Also note that the 'wait to start' light is not a glow plug light. The glow plugs should stay on well after the light goes out.

 

نتيجة بحث Google عن الصور حول http://www.members.shaw.ca/k2pilot/Glow%2520plug%2520relay.jpg

Basically, the large post on the right is your battery terminal, large post on the left is your GP power. top small post is your trigger, and the small bottom post is your ground.

 

As you indicated 1 big post has power all the time. The two small wires are controlling the GPR. The RED/LTGRN small wire has power with key on. The PPL/ORG small wire is pulled to ground by the PCM causing the relay to pull in.

When measuring be sure the engine is cold and measure quickly because if you wait to long ~ 30 second up to 2 minutes then after that the relay is disengaged and you will measure as described in your post above.