Hard start cold, GP=good
Thread Starter
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Fleet Mechanic
Joined: Oct 2012
Posts: 1,943
Likes: 21
Hard start cold, GP=good
Hi,
I have an '88 van with a 7.3 idi. As the tempature has been dropping it is getting harder to start up in the morning. Once it starts once, it will fire right back up. Through searching I had found that this is usually a GP issue, or a GP relay issue. Yesterday I tested all my GP's with a test light, and they all showed good. The previous owner (I just purchased it last week) said that this had been an issue and he had replaced the GP relay last summer without success. I watched the GP light and it stays on for the 8-10 second. If I cycle the GP's a few times it will eventually fire up. I was going to start by checking voltage leaving the relay to the GPs (green wire). If I have power to the green wire I would move to each GP and test for voltage at the GP boot. If I have no power leaving the relay then I will check for voltage coming in. If I have voltage in, but not out then the relay is bad. If no voltage going in, then I can work backwards.
Besides doing this, is there anything else I should check. A fuse? Would anything not GP related cause this issue? Thanks
I have an '88 van with a 7.3 idi. As the tempature has been dropping it is getting harder to start up in the morning. Once it starts once, it will fire right back up. Through searching I had found that this is usually a GP issue, or a GP relay issue. Yesterday I tested all my GP's with a test light, and they all showed good. The previous owner (I just purchased it last week) said that this had been an issue and he had replaced the GP relay last summer without success. I watched the GP light and it stays on for the 8-10 second. If I cycle the GP's a few times it will eventually fire up. I was going to start by checking voltage leaving the relay to the GPs (green wire). If I have power to the green wire I would move to each GP and test for voltage at the GP boot. If I have no power leaving the relay then I will check for voltage coming in. If I have voltage in, but not out then the relay is bad. If no voltage going in, then I can work backwards.
Besides doing this, is there anything else I should check. A fuse? Would anything not GP related cause this issue? Thanks
Post Fiend
Joined: Jan 2005
Posts: 8,402
Likes: 10
https://www.ford-trucks.com/forums/9...le-system.html Have a read here. It does sound like a glowplug problem or slow cranking on the starter.
Thread Starter
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Fleet Mechanic
Joined: Oct 2012
Posts: 1,943
Likes: 21
https://www.ford-trucks.com/forums/9...le-system.html Have a read here. It does sound like a glowplug problem or slow cranking on the starter.
It seems to turn over just fine and has all new batteries. Problem is, since I am completely new to diesels I don't have anything for comparison.
Fleet Owner
Joined: Jul 2006
Posts: 20,357
Likes: 813
From: Mi'kma'ki
now i know they should actually start easier than a gas engine.mine sure does.
here i was brand new to diesels and learning what to expect for cold starts,and how i made my truck start instantly with temps down to around 0 without ever to this day,even testing the block heater yet:
https://www.ford-trucks.com/forums/8...old-start.html
this will help you diagnose the complete '87-94 GP system:
https://www.ford-trucks.com/forums/1...low-plugs.html
Thread Starter
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Fleet Mechanic
Joined: Oct 2012
Posts: 1,943
Likes: 21
that was my issue.i didn't know what to expect.
now i know they should actually start easier than a gas engine.mine sure does.
here i was brand new to diesels and learning what to expect for cold starts,and how i made my truck start instantly with temps down to around 0 without ever to this day,even testing the block heater yet:
https://www.ford-trucks.com/forums/8...old-start.html
this will help you diagnose the complete '87-94 GP system:
https://www.ford-trucks.com/forums/1...low-plugs.html
now i know they should actually start easier than a gas engine.mine sure does.
here i was brand new to diesels and learning what to expect for cold starts,and how i made my truck start instantly with temps down to around 0 without ever to this day,even testing the block heater yet:
https://www.ford-trucks.com/forums/8...old-start.html
this will help you diagnose the complete '87-94 GP system:
https://www.ford-trucks.com/forums/1...low-plugs.html
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Post Fiend
Joined: Nov 2005
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From: Charles Town, W bygod Va
Be sure to use motorcraft plugs.
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Thread Starter
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Fleet Mechanic
Joined: Oct 2012
Posts: 1,943
Likes: 21
The vids were very helpful. Mine sounds more like the first one, so I may have a dieing starter too.
i ain't rite
Joined: Mar 2005
Posts: 65,481
Likes: 5,542
From: Marlboro Mental Hospital.
it is amazing what an old wore out starter will do to keep one of these beasts from starting.
the worst part is they die over time, so you don't realize it is bad until some idiot like me posts videos like this.
that bad starter was 200,000 + miles, so i never realized it was shot till i got in another truck with a new starter.
and that one died 2 days later leaving me stranded in the rebuilders parking lot where i went to drop off one to be rebuilt.
lucky for me i have known him for over 30 years, and he had one sitting on the shelf he just put together. so we traded the good for the bad and $100, and his guy put it in while we busted each others chops.
the worst part is they die over time, so you don't realize it is bad until some idiot like me posts videos like this.
that bad starter was 200,000 + miles, so i never realized it was shot till i got in another truck with a new starter.
and that one died 2 days later leaving me stranded in the rebuilders parking lot where i went to drop off one to be rebuilt.
lucky for me i have known him for over 30 years, and he had one sitting on the shelf he just put together. so we traded the good for the bad and $100, and his guy put it in while we busted each others chops.
Thread Starter
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Fleet Mechanic
Joined: Oct 2012
Posts: 1,943
Likes: 21
Thanks. I ordered a set from Rock Auto. They are Motorcraft ZD9's.
Wierd thing is they did not have them listed under my vehicle, I had to do a part number search to find them.
Wierd thing is they did not have them listed under my vehicle, I had to do a part number search to find them.
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