Question About GPR Hard cold starting
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Question About GPR Hard cold starting
Hey Guys,
I have a 2001 F-350 7.3L Powerstroke. 48,000 miles. I've been having trouble with cold starts. So far it has always started but is taking a lot of cranking, but it hasn't gotten too cold yet so I'm worried about when it does. I ohmed out the the glow plugs and am getting close to 0 resistance. The GPR has 12.5 volts on the hot side and when the relay is closed 10.5 on the other side. Is that difference in voltage in the GPR enough to screw up the Glow Plugs heating up? If I plug it in at night it starts right up. I'm worried about when I am at work for 16 hours and dont have a place to plug it in this winter. BTW this is my first winter with the truck.
Any info would be appreciated.
Thanks,
Tom G
I have a 2001 F-350 7.3L Powerstroke. 48,000 miles. I've been having trouble with cold starts. So far it has always started but is taking a lot of cranking, but it hasn't gotten too cold yet so I'm worried about when it does. I ohmed out the the glow plugs and am getting close to 0 resistance. The GPR has 12.5 volts on the hot side and when the relay is closed 10.5 on the other side. Is that difference in voltage in the GPR enough to screw up the Glow Plugs heating up? If I plug it in at night it starts right up. I'm worried about when I am at work for 16 hours and dont have a place to plug it in this winter. BTW this is my first winter with the truck.
Any info would be appreciated.
Thanks,
Tom G
Post Fiend
Joined: Feb 2007
Posts: 14,541
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From: Dallas-Ft. Worth
That's a 2V drop. A little high I think. The GPs should be around 0.2 to 1.0 ohm, ideally. No more than 2 ohms, IIRC. Is that what you saw?
EDIT: When I ohmed out mine, all of them were 0.2 to 0.8 ohms. I haven't checked my GPR yet, but I guess I could, just to see what the drop is there. Mine starts fine, but it doesn't get that cold here. AFAIK, my GPR has never been replaced, BTW.
EDIT: When I ohmed out mine, all of them were 0.2 to 0.8 ohms. I haven't checked my GPR yet, but I guess I could, just to see what the drop is there. Mine starts fine, but it doesn't get that cold here. AFAIK, my GPR has never been replaced, BTW.
Go Bills !
Joined: Jan 2008
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From: Buffalo, NY
Mine read .5 across the board. From GP to ground. Right in the middle of the spec Joe stated. I have a hard believeing all the GP's as shot. It apears the GPR is working. Dad had a similiar acurance recently and found out his batteries had no aperage output. I wonder if you batteries are shot from the 90amp spike and 60 amp to maintain the plugs. He put in new batteries and that was the cure.
How you can test that is, Jump the batteries with another vehicle in the morning and see if it behaves better seeing it has more battery muscle. Free test.
How you can test that is, Jump the batteries with another vehicle in the morning and see if it behaves better seeing it has more battery muscle. Free test.
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I may be doing something wrong but I keep getting 0 ohms once the meter settles. If I use the battery ground and do it I get 1.6 to 2.0 ohms. I'm pretty sure I have a good chassis ground. I can measure 12.5 volts to the battery from the chassis ground.
If the GPs really are coming up 0 ohms does that mean all of the GPs are bad?
If the GPs really are coming up 0 ohms does that mean all of the GPs are bad?
Post Fiend
Joined: Feb 2007
Posts: 14,541
Likes: 2
From: Dallas-Ft. Worth
No -- where are you measuring them? If you're trying to measure all of them at once at the relay, it will be very close to 0 ohms. You have to pull the plug off the VC connector and measure one at a time. I'll get the pin-out. Hang on....
EDIT: Here's the pin-out looking at the connector on the engine after disconnecting the harness:
G - G - I - I - C - I - I - G - G
G = glow plug
I = Injector return
C = Injector common feed
Measure between "G" & a good ground point.
EDIT: Here's the pin-out looking at the connector on the engine after disconnecting the harness:
G - G - I - I - C - I - I - G - G
G = glow plug
I = Injector return
C = Injector common feed
Measure between "G" & a good ground point.
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I pulled the plug on both sides and measured one at a time. Each one would come up zero. I dont know what to make of that. I'm gonna change out the GPR but I have to go away with work for 10 days so I'll have to do it when I get back. I'll order it and it should be here before I get back.
Thanks so much for the help. I thought about the batteries being weak so I put them on charge for a few hours this afternoon and then the truck started right up. Although it's not too cold today.
When I get back I'm sure the normal weather will be here. I'll write to tell you guys what happens.
Thanks so much for the help. I thought about the batteries being weak so I put them on charge for a few hours this afternoon and then the truck started right up. Although it's not too cold today.
When I get back I'm sure the normal weather will be here. I'll write to tell you guys what happens.
Last edited by tjgalinski; Nov 10, 2009 at 05:15 PM. Reason: forgot something
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Well I put the Stancor GPR in yesterday. It now measures 11.7 volts on the other side when I have the GPs running. Still having a hard time with start up. Still getting 0 ohms on the GP test. Ugh!
Lead Driver
Joined: Jan 2007
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From: Kiowa CO
Maybe you already have done this but clean your battery terminals until they shine. A bad ground or positive lead(s) will get you chasing your tail with your GPR or plugs. You don't realize how much juice is being pulled from your batteries to get those plugs hot until the outside temp drops.
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Thanks, I cleaned the terminals really nice with the same result. The batteries seem to be holding a full charge. 12.78 volts in the morning before starting. I also borrowed a different multimeter and retested the resistance on the glow plugs and they still come up with zero resistance. I wonder if that means the glow plugs are bad? The truck so far has always started but it takes a while and I get white smoke on start up.
