Cold Start Problems- GP Relay OK
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New User
Joined: Dec 2013
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Cold Start Problems- GP Relay OK
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!
Posting Guru
Joined: Oct 2012
Posts: 1,910
Likes: 2
From: Hat Creek Ca
You mentioned minimal loss between terminals. Which ones? When the GP's are energized you should see a significant voltage drop at the large terminals vs static battery voltage (when the engine is running, ~14 V) but not below ~10.5V while cranking. If you need to keep charging the batteries that may be your problem, but you said it starts OK when plugged in so ???
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New User
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You mentioned minimal loss between terminals. Which ones? When the GP's are energized you should see a significant voltage drop at the large terminals vs static battery voltage (when the engine is running, ~14 V) but not below ~10.5V while cranking. If you need to keep charging the batteries that may be your problem, but you said it starts OK when plugged in so ???
I believe I was seeing around 10.7V key on/engine off (waiting to start) and about 12.5-12.7 at the batteries with the key off/engine off
Senior User
Joined: Nov 2014
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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!
My guess is the batteries.
You can have the batteries be fully charged and give you 12V jsut fine but still not be able to provide enough current to turn over the starter fast enough.
Stop by autozone and have them tested.
Now, when you do, you can tell the testing person to input a specific amperage to test for. My batteries tested at 600 and 800 which prompted me to replace them. Needles to say, do not forget to separate them during test and replace both if either has failed.
THE cheapest (and incidentally awesome quality) batteries you can find are Interstate (850CCA) available at Costco for about $160 per set 3 year 100% warranty. Yes, that is for both batteries.
Keep in mind that if it is indeed a battery problem continuing to start the truck that way will ruin your starter and/or whatever else electrical is in the middle. Reason for it is less voltage=more current needed. Ohms law and whatnot.
Cargo Master
Joined: Jan 2009
Posts: 2,800
Likes: 31
From: OKC, OK
I agree address the batteries first. I just had to replace mine at 2 years old. Night and day in the starting.
Also just because the GPR seems fine does not mean the glow plugs are good. You need to ohm each plug individually. Do a search and you will find how to do it.
Also just because the GPR seems fine does not mean the glow plugs are good. You need to ohm each plug individually. Do a search and you will find how to do it.
Senior User
Joined: Nov 2014
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Which ones failed so quickly? What prompted you to replace?
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Cargo Master
Joined: Jan 2009
Posts: 2,800
Likes: 31
From: OKC, OK
They were Duralast from "The Zone" they had a long warranty comparatively. Honestly it seams to be around every 3 years when they need to be replaced. My teuck was having a hard time starting in colder, not cold, weather and if it sat for more than a day I would have to charge them. I don't have a costco around here or I would buy my batteries from there. I will look for interstates when this set goes out since they won't be under warranty. When I bought them they were the best deal around here when you compared CCA's, warranty and price.
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Joined: Nov 2014
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My thought exactly. You could spend double and maybe get 4-5 years.
Lead Driver
Joined: May 2007
Posts: 5,613
Likes: 9
From: Flagstaff, Arizona
Sorry to "semi" hijack this post, but I'm having very similar numbers on my NO start issue. I am getting a maximum of 10.6-10.7 on the GPR with key on (wait to start) and at the batteries I am getting 12.13. I'm not sure which to replace first, GPR or batteries? I have Optima yellow tops, manafactured February 2000. I'm pretty sure it's a battery issue because of age, but no reason to replace them if their not read yet. I have had zero issues with them dying and needing a charge, but the cold start thing is new..........thoughts?
Posting Guru
Joined: Oct 2012
Posts: 1,910
Likes: 2
From: Hat Creek Ca
UP there
The voltage you are reading with the GP's energized is minimal at best. Injectors need 10.5 V to fire and your meter readings could easily be off a few tenths. 14 year old batteries? Change them.
The voltage you are reading with the GP's energized is minimal at best. Injectors need 10.5 V to fire and your meter readings could easily be off a few tenths. 14 year old batteries? Change them.
Lead Driver
Joined: May 2007
Posts: 5,613
Likes: 9
From: Flagstaff, Arizona
Sorry....that was a typo! They are Feb 2010
Lead Driver
Joined: May 2007
Posts: 5,613
Likes: 9
From: Flagstaff, Arizona
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...