F250 SD hard start
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Junior User
Joined: Feb 2004
Posts: 93
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From: Oregon
Here are a couple pics of the ground wire I cleaned up.
I'm second guessing my fix now
When I disconnected it last Sunday I didn't show power before the FP relay - cleaned it, reattached and had power to FP relay. This morning I decided to validate - disconnected the ground but still had power to FP relay. Kind of bummed me out thinking I may still have a problem. It has been starting past two days. Any ideas on what else to check. Is the FP power up sequence key-FP fuse-FP relay-interia switch-FP? I need to track down where the power break is occurring. Thanks
I'm second guessing my fix now
When I disconnected it last Sunday I didn't show power before the FP relay - cleaned it, reattached and had power to FP relay. This morning I decided to validate - disconnected the ground but still had power to FP relay. Kind of bummed me out thinking I may still have a problem. It has been starting past two days. Any ideas on what else to check. Is the FP power up sequence key-FP fuse-FP relay-interia switch-FP? I need to track down where the power break is occurring. Thanks
Hotshot
Joined: Jan 2004
Posts: 19,762
Likes: 1,079
From: St Louis
Okay, that ground is designated as G100 and should have two wires on it, a black one and a blue/yellow wire both of which are visible.
The blue/yellow wire is the case ground for the PCM. If it didn't have reliable connection to ground, it's relatively unlikely you'd ever have problems, it's more an insurance policy against noise than an operational requirement. Therefore, it's probably just a coincidence that the engine started multiple times after messing with that wire.
BTW, if that wire still looks green to you, you may wish to have your eye doctor conduct a screening test for colorblindness.
Working with color-coded stuff can be tough if one's eyes don't correctly register the colors. Of course, that wire might just be weathered enough that it's hard to distinguish, I'll leave that up to you.
The blue/yellow wire is the case ground for the PCM. If it didn't have reliable connection to ground, it's relatively unlikely you'd ever have problems, it's more an insurance policy against noise than an operational requirement. Therefore, it's probably just a coincidence that the engine started multiple times after messing with that wire.
BTW, if that wire still looks green to you, you may wish to have your eye doctor conduct a screening test for colorblindness.
Working with color-coded stuff can be tough if one's eyes don't correctly register the colors. Of course, that wire might just be weathered enough that it's hard to distinguish, I'll leave that up to you.
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Junior User
Joined: Feb 2004
Posts: 93
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From: Oregon
Well that's good to know, I thought I had it figured out. May have to breakdown and buy a wiring diagram. I need to figure out the path the power flows from the key to the fuel pump: key - PCM relay - PCM - FP fuse - FP relay -inertia switch - FP? I think the problem is somewhere behind the FP relay. Back to the drawing board. 
Hotshot
Joined: Jan 2004
Posts: 19,762
Likes: 1,079
From: St Louis
Go read my instructions in this thread: https://www.ford-trucks.com/forums/1...-start-up.html
Those instructions apply to your situation, you have to determine where to focus your efforts.
It also helps if you tell us what engine you have...
Those instructions apply to your situation, you have to determine where to focus your efforts.
It also helps if you tell us what engine you have...
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