Hard starting when motor is cold

[Dieseltooldude]

I started by replacing the glow plug relay last year. It did not help. I have just plugged in the truck when it is cold. Now that it is becoming winter again I want to get the glow plugs working. New glow plugs and valve cover gaskets in the past 2 weeks. New glow plug relay again tonight. Replaced because the 2nd large post did not get hot with the key on. The new relay does the same thing. I took off the blue wire(I believe is a fusible link) off of that large post and then it appears that the relay works. This is a 2000 F550 7.3. Thanks for any help

[85_305]

Whats a hard start? Excessive cranking? What are the temperatures when you cold start it?

Try cycling the gpr several times for now

[Dieseltooldude]

My hard start is that it cranks for a long time and does not want to start. When i plug the truck in it fires right off. When the motor is warm during the day it also starts fine. I would guess that when it gets below 50 degrees it is harder to start. We are getting down to the mid 30's now at night. I do not think that cycling the glow plug relay will help. When testing the relay the large post from battery power will light a test light. The way I understand it the second large post should get hot when turning on the key and it does not. The wait to start light is on in the dash but relay does not trip. That is why I replaced the relay last night. It is doing the same thing as the first relay. When I take off the blue wire off of that 2nd large post, then it appears that the relay works correctly. I am not sure why when all the wires are hooked up it does not want to work. When I checked pictures of the relay on line and the hook up of the wires it appears that I have them correct. Thank you in advance for any help.

[jesilvas]

Troubleshooting GPR & GP's
Winter Operation, Hard Starting, Hissing Sound Etc...

[frttrain]

I have the same problem, power in and no power out. If you test the small wires one has 12v and one has 0.3v koeo. Install on GPC and both wires now show 12v but still nothing out to glow plugs. New GPC today and same problem.

[Dieseltooldude]

My truck is a 2000. On the post that should get hot when the key is turned on there is a small blue wire that quickly changes color to a yellow with a green stripe( i think that is the right color change). When I take that wire off the relay seems to work fine, although I did not check to see if power then goes to the glowplugs. Do you have a 2nd wire on that post similar to mine? And is yours a 7.3 about 2000? I have seen on line pictures that do show that wire but I am not sure what it does.