[jandoe]

I have been having cold start problems and checked the GPR and found it to have voltage of 12.8 on the hot side and zero on the GP side. Bought new one from Ford, replaced it and checked again and same result, zero on the GP side. Now what, have checked through the search and did not find a thread with this issue. Also truck has been missing, enough to throw check engine light, seems to do it more when its raining outside. Had it scanned at Ford and did not happen when there, they said it all seems ok, so no diagnosis, just checking to see if someone has had this issue. 02 7.3 with 260k

 

[RT]

I'm assuming you found 12.8 on the large lug connected to the battery. What you need to check next is to see if you have 12v+ on the small lug when the key is turned on and if the other small lug is grounded by the PCM for the prescribed glow plug duration. The way the system is set up, one side of the activation side (small lugs) is hot as long as the key is in the run position and the other side is grounded for the time the PCM commands. I suspect you have a blown fuse or bad wire on the small positive terminal.

 

[klhansen]

Now what, have checked through the search and did not find a thread with this issue.

Check the Hard/No Start link in my signature.

 

[ArcticDriver]

And, ofcourse, you want the engine to be cold when you perform all the GPR tests.

 

[lance_kohler]

Check fuel bowl heater and air heater relay aswell as gpr

 

[ArcticDriver]

Check fuel bowl heater and air heater relay aswell as gpr

But those would not affect the zero reading on the GPR, right?

 

[gregoaustralia]

I have similar problem... But if i just wait for about 30 seconds ( Could be more ) I can tell by the volt gauge ( After market )dropping suddenly that the relay had come in.. Then i just wait 5 or so seconds and it starts perfectly. No idea why the signal to the relay is taking so long to do its thing, and i havent been able to find any data on the subject, but at least now i know whats happening i know it will start. I was thinking on changing GPR to a manual system, but havent got around to it yet.