Cold Start Problems- GP Relay OK
Post Fiend
Joined: Sep 2006
Posts: 7,426
Likes: 6
From: Sioux Falls, SD
It is holding pretty steady right around 250 rpms while cranking. It doesn't even hesitate to crank, but maybe it's just not getting enough juice? It gets to the point of almost firing, but doesn't quite do it. It will start if plugged in, but obviously I can't rely on that if I'm not at home.....
Again, sorry for the hijack, but this info will most likely help the original poster as we're having similar issues...
Again, sorry for the hijack, but this info will most likely help the original poster as we're having similar issues...
In addition, You need at least 100 rpm's (which you have) and ICP of 500 psi. If you unplug the ICP sensor the PCM will not get the reading from the sensor and default to 750 psi.
It could easily be the batteries, I have no luck getting more than 2 winters out of batteries on my 7.3L's in South Dakota. But I would test the GPR and ohm the glow plugs first so your not throwing money at the problem. Then have the batteries load tested and make sure your getting enough CCA's. It's easy to do and doesn't cost anything.....
Here is a good link and 3 videos at the bottom o the page:
https://sites.google.com/site/woodnt...ow-plug-system
Lead Driver
Joined: May 2007
Posts: 5,613
Likes: 9
From: Flagstaff, Arizona
Like Hydro Man 17 posted, you need at least 10.5V when the glow plugs are on. Have you tried starting the truck after the GPR clicks off? Either wait till you hear the audible click from the GPR or see the voltage climb back up on your meter. They glow plugs will still be hot.
In addition, You need at least 100 rpm's (which you have) and ICP of 500 psi. If you unplug the ICP sensor the PCM will not get the reading from the sensor and default to 750 psi.
It could easily be the batteries, I have no luck getting more than 2 winters out of batteries on my 7.3L's in South Dakota. But I would test the GPR and ohm the glow plugs first so your not throwing money at the problem. Then have the batteries load tested and make sure your getting enough CCA's. It's easy to do and doesn't cost anything.....
Here is a good link and 3 videos at the bottom o the page:
https://sites.google.com/site/woodnt...ow-plug-system
In addition, You need at least 100 rpm's (which you have) and ICP of 500 psi. If you unplug the ICP sensor the PCM will not get the reading from the sensor and default to 750 psi.
It could easily be the batteries, I have no luck getting more than 2 winters out of batteries on my 7.3L's in South Dakota. But I would test the GPR and ohm the glow plugs first so your not throwing money at the problem. Then have the batteries load tested and make sure your getting enough CCA's. It's easy to do and doesn't cost anything.....
Here is a good link and 3 videos at the bottom o the page:
https://sites.google.com/site/woodnt...ow-plug-system
Post Fiend
Joined: Sep 2006
Posts: 7,426
Likes: 6
From: Sioux Falls, SD
Hi All,
My dad has a 2000 F350 Dually 7.3L Automatic ~250k miles-
The batteries went dead, he put it on a charger which he left under the hood (with the hood not fully closed) went to work and it rained- he thinks it got a little wet under the hood- ever since then it will not cold start. I put it on the block heater overnight and it started right up and ran fine.
Today I got into it a little deeper- its 42˚F right now but in the low 30s overnight. Put the truck on a charger to keep the batteries healthy and I checked the GPR- actuates well, minimal loss between posts- stays on for a while then clicks off- seems totally normal. Truck still refuses to start, just cranks. I plugged it into the block heater for about 15-20 min and it started right up, no smoke, no surge, runs perfect.
Not sure where to go from here? I'm seeing IDM/UVCH etc tossed around and while I'm handy with euro diesels I'm new to 7.3s.. any ideas on where to go from here?
Thx in Advance!
My dad has a 2000 F350 Dually 7.3L Automatic ~250k miles-
The batteries went dead, he put it on a charger which he left under the hood (with the hood not fully closed) went to work and it rained- he thinks it got a little wet under the hood- ever since then it will not cold start. I put it on the block heater overnight and it started right up and ran fine.
Today I got into it a little deeper- its 42˚F right now but in the low 30s overnight. Put the truck on a charger to keep the batteries healthy and I checked the GPR- actuates well, minimal loss between posts- stays on for a while then clicks off- seems totally normal. Truck still refuses to start, just cranks. I plugged it into the block heater for about 15-20 min and it started right up, no smoke, no surge, runs perfect.
Not sure where to go from here? I'm seeing IDM/UVCH etc tossed around and while I'm handy with euro diesels I'm new to 7.3s.. any ideas on where to go from here?
Thx in Advance!
the 7.3L needs the following to start:
@ 10.5 volts while cranking
100 rpm's
ICP of 500 psi
@ 50 psi fuel pressure
Here is a great trouble shooting link and a great Glow Plug system check link.
http://oregonfuelinjection.com/pdf/f...diagnostic.pdf
https://sites.google.com/site/woodnt...ow-plug-system
Post Fiend
Joined: Sep 2006
Posts: 7,426
Likes: 6
From: Sioux Falls, SD
Thanks for all that info Rich! Since these batteries are approaching 5 years, I pulled them out, and I'm going to replace them today, if they are okay, odds are they wouldn't be for long. Where I live in AZ is at 7000 ft elevation, it was 12* this morning, so batteries take a beating. 2 years ago I did a GPR, and last year I replaced all glow plugs.
I'd suspect batts first also, but it wouldn't be unheard of for the GPR to go bad as well. Especially if it was aftermarket & not OEM.
Thread Starter
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New User
Joined: Dec 2013
Posts: 13
Likes: 0
No worries UP There just wanting this to get resolved- I played around a little last night and realized that though my father said the battery light has been on for a long time and its started fine with it on- the alternator is not putting out enough voltage. At idle no accessories on I'm seeing 12.3v and with a load (highbeams/blower motor) 12.05v... Resting voltage after coming off the charger is around 12.7v IIRC.. Alternator has power at both pins of the connector when it is idling, and has a good connection at the output.. alt looks new.
I'm going to start by trying to get it to charger properly, followed by battery health, followed by GP pin outs and IDM etc.
I'll keep you updated, and I'd appreciate if you do the same! too many of these threads end with "I'll try it" and no resolution if that fixed the problem.
Thx!
I'm going to start by trying to get it to charger properly, followed by battery health, followed by GP pin outs and IDM etc.
I'll keep you updated, and I'd appreciate if you do the same! too many of these threads end with "I'll try it" and no resolution if that fixed the problem.
Thx!
Lead Driver
Joined: May 2007
Posts: 5,613
Likes: 9
From: Flagstaff, Arizona
Okay.....here is my update. I replaced both batteries with Optima Red tops, tried starting the truck, acted exactly the same! My batteries were probably about to shoot craps anyways, so no biggie. The new ones tested 12.7.
I then replaced the GPR, and the truck did start, but didn't seem to just JUMP right on it like normal. The ambient temperature warmed up to 27* currently, so I'm hoping that isn't the reason I was able to get it fired up. The new GPR tested at 11.35, so it is significantly higher then the one I replaced, although I'm not convinced the higher numbers I got weren't also helped along by the fresh batteries!
The REAL test will come after sitting all night, not plugged in. Another thing that isn't a "typical" situation with my truck, is I have the T5 Rotella syn blend, instead of T6 full syn. I wasn't able to find any T6 anywhere a couple months ago when I changed oil before a hunt. My truck definitely likes T6 over T5, but I'm not so sure either that could affect cold starts to the point of FIRING, only after it's running.
I then replaced the GPR, and the truck did start, but didn't seem to just JUMP right on it like normal. The ambient temperature warmed up to 27* currently, so I'm hoping that isn't the reason I was able to get it fired up. The new GPR tested at 11.35, so it is significantly higher then the one I replaced, although I'm not convinced the higher numbers I got weren't also helped along by the fresh batteries!
The REAL test will come after sitting all night, not plugged in. Another thing that isn't a "typical" situation with my truck, is I have the T5 Rotella syn blend, instead of T6 full syn. I wasn't able to find any T6 anywhere a couple months ago when I changed oil before a hunt. My truck definitely likes T6 over T5, but I'm not so sure either that could affect cold starts to the point of FIRING, only after it's running.
Cargo Master
Joined: Jan 2009
Posts: 2,800
Likes: 31
From: OKC, OK
I agree. 14 year old batteries? A friend used to put optimas in his truck but they never lasted any longer than regular and the CCAs weren't as good. You got your $$ out of those.
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Lead Driver
Joined: May 2007
Posts: 5,613
Likes: 9
From: Flagstaff, Arizona
Thread Starter
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Joined: Dec 2013
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Ok, I am dragging this back from the grave. I travel a lot for work and I have been on the road since the start of January- right ater I left my father had the alternator replaced, got two new Interstate batteries from Costco, and told me it was running great, it turns out he had been plugging it in so of course it was running great.
He called the other day because he was upset it didn't start when it was in the high 30s and uplugged. He said it is doing the same thing- cranking over fine, and sounding like it is 80% of the way to starting, then it just won't.
Someone mentioned unplugging the ICP to get the full 750 psi- is that the next step in troubleshooting this? I'm not there and he is mechanically adept, just not a diesel guy so I'm trying to explain a lot of stuff over the phone to him.
Thanks again for everyone's help.
Tim
He called the other day because he was upset it didn't start when it was in the high 30s and uplugged. He said it is doing the same thing- cranking over fine, and sounding like it is 80% of the way to starting, then it just won't.
Someone mentioned unplugging the ICP to get the full 750 psi- is that the next step in troubleshooting this? I'm not there and he is mechanically adept, just not a diesel guy so I'm trying to explain a lot of stuff over the phone to him.
Thanks again for everyone's help.
Tim
Posting Guru
Joined: Oct 2008
Posts: 1,080
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Ok, I am dragging this back from the grave. I travel a lot for work and I have been on the road since the start of January- right ater I left my father had the alternator replaced, got two new Interstate batteries from Costco, and told me it was running great, it turns out he had been plugging it in so of course it was running great.
He called the other day because he was upset it didn't start when it was in the high 30s and uplugged. He said it is doing the same thing- cranking over fine, and sounding like it is 80% of the way to starting, then it just won't.
Someone mentioned unplugging the ICP to get the full 750 psi- is that the next step in troubleshooting this? I'm not there and he is mechanically adept, just not a diesel guy so I'm trying to explain a lot of stuff over the phone to him. Thanks again for everyone's help. Tim
He called the other day because he was upset it didn't start when it was in the high 30s and uplugged. He said it is doing the same thing- cranking over fine, and sounding like it is 80% of the way to starting, then it just won't.
Someone mentioned unplugging the ICP to get the full 750 psi- is that the next step in troubleshooting this? I'm not there and he is mechanically adept, just not a diesel guy so I'm trying to explain a lot of stuff over the phone to him. Thanks again for everyone's help. Tim
Since your resurrecting this, we can continue to assume the GP system has been eliminated as a probable cause?
Another thing he can check on a pre 02 is the Tachometer movement while cranking. He should see 100 RPM's while cranking. If, it falls to 0 RPM the CMP is falling out of the communications loop which will prevent starting.
That's about all I can offer not knowing his abilities and available tools.
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