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-   -   7.3 if cold wont start (https://www.dieselbombers.com/ford-powerstroke-99-03-7-3l/44106-7-3-if-cold-wont-start.html)

CSIPSD 03-07-2010 10:56 AM


Originally Posted by weatherby (Post 511284)
OK....Thanks CSIPSD....Well, I now know I checked the wrong relay, I checked the one closest to the radiator. I am going out there in a little bit to re-check the GPR again. Should I have power on any of the studs of the GPR with the key off aside from the main power lead, and then what should the volt reading be on the studs should they read the same as the main power lead (12v) or a little less .
I will let you know what I find.

With the key off the only stud that has power should be the big one closest to the passanger side.

You should have the same or close to the same voltage across the GPR when its on. Little tough to throw a number at it, as every truck will have differant voltage in the batterys.


BTW, Welcome to the site!!!

weatherby 03-07-2010 11:39 AM

Just went out and re-checked the GPR and this is what I found....with the key off, I have no power on the two smaller studs....with the key on, I have power on ONLY ONE of the smaller studs (the stud closest to the other relay) and the stud closest to the fire wall has no power. That tells me power is not going across the relay correct? or could there be anything else that would cause the relay not to work. I don't know much about diesels so I have to ask.:c::w2:

CSIPSD 03-07-2010 11:41 AM

Just check the big studs... But you should have power with key on to both smaller studs.

weatherby 03-07-2010 11:57 AM

Thanks for that diagnoses, It was spot on, and yes I have power to both big studs and only one small stud "with the key on". I will be going out to get that GPR you suggested.:tu:

CSIPSD 03-07-2010 12:04 PM

With the key on and power to both big studs then you are fine, the GPR is working. Time to dig a little deeper...

weatherby 03-07-2010 12:25 PM


Originally Posted by CSIPSD (Post 511346)
With the key on and power to both big studs then you are fine, the GPR is working. Time to dig a little deeper...

Well then is it normal to not have power to both small studs with the key on

CSIPSD 03-07-2010 03:38 PM

I dont know, I would have to go test mine.

But if you have power to the drivers side of the GPR (big stud) then your GPR is working.

The small studs are controls,

weatherby 03-07-2010 04:10 PM

OK.. That makes seance. I did test the voltage on the drivers side stud and I get 10 volts, I have both my batteries on charge now to see if it makes any diff when I try to start it later.
Is it possible that I am loosing fuel pressure wile the truck sits for a wile??

CSIPSD 03-07-2010 05:04 PM

No, you have an electric fuel pump, when you turn the key on the pump starts and pressurizes the rails. All PSD's will show 0-10psi fuel pressure in the rails no more then 30 seconds after shut down.

You could have a HPO res issue, but I doubt it. Next time you cold start it, before you crank remove one of the small caps on the HPO res and see if there is oil in there. Should be within 3/4" of the top.

weatherby 03-07-2010 06:52 PM

Ware do I find the HPO and what does that stand for


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