Fuel Injector Wiring Harness Removal/Repair
01-05-2019, 08:48 PM
#1
Fuel Injector Wiring Harness Removal/Repair
Is there any way to remove/repair and reinstall the fuel injector wiring harness on a 1995 F150 XLT 5.0 L without having to remove the air intake plenum? Rodents have chewed through the wires from the harness to the injector connector on one that can be reached but not visualized. If I could just disconnect the injectors, pull out the harness section, and splice on a new connector without having to remove the plenum, that would save a lot of time and work. Can it be done? Or am I going to have to disconnect the throttle body, etc. and replace the gaskets when I remove the plenum? Thanks!
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Tsusieq (01-31-2021)
01-06-2019, 01:14 PM
#2
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The plenum gasket doesn't necessarily have to be replaced every time the plenum comes off the intake, but it does sometimes get sucked in just from normal operation (creating a vacuum leak), and it's not expensive, so it wouldn't hurt to change it. Click this & read the caption:
(phone app link)
The hardest parts of pulling the plenum are usually:
1) getting the first nut off the RHS support bar without winding the ground strap up; a VERY-thin open-end wrench is usually necessary. Look at the lower Right panel of this diagram:
(phone app link)
2) putting a tool on the center T40 bolt in the plenum gap.
(phone app link)
At this age, you may also find the coolant nipples on the throttle body rusted. While the plenum is off, replace any PCV components that are aged. If the valve cover gaskets are leaking, replace them with the ones linked in this caption:
(phone app link)
If the intake gaskets aren't leaking, DON'T MESS WITH the intake bolts - they commonly break off during removal, and they're difficult to extract.
But if you really want to avoid pulling the plenum, just unplug the damaged connector from its injector, either extend its wiring or buy a new connector pigtail & extend those wires, and then splice them into the engine harness where it's accessible on the driver's side. Exactly where & how depends on exactly how your truck's engine is built. Click this, read the caption carefully, study the truck, and edit your signature to show ALL its details automatically with each of your posts:
(phone app link)
(phone app link)
The hardest parts of pulling the plenum are usually:
1) getting the first nut off the RHS support bar without winding the ground strap up; a VERY-thin open-end wrench is usually necessary. Look at the lower Right panel of this diagram:
(phone app link)
2) putting a tool on the center T40 bolt in the plenum gap.
(phone app link)
At this age, you may also find the coolant nipples on the throttle body rusted. While the plenum is off, replace any PCV components that are aged. If the valve cover gaskets are leaking, replace them with the ones linked in this caption:
(phone app link)
If the intake gaskets aren't leaking, DON'T MESS WITH the intake bolts - they commonly break off during removal, and they're difficult to extract.
But if you really want to avoid pulling the plenum, just unplug the damaged connector from its injector, either extend its wiring or buy a new connector pigtail & extend those wires, and then splice them into the engine harness where it's accessible on the driver's side. Exactly where & how depends on exactly how your truck's engine is built. Click this, read the caption carefully, study the truck, and edit your signature to show ALL its details automatically with each of your posts:
(phone app link)
The following 2 users liked this post by Steve83:
NWGAcarguy (01-10-2019),
Tsusieq (12-16-2021)
01-10-2019, 09:02 PM
#3
Sorry to be so late in expressing my appreciation for the incredibly helpful reply. I have been trying to squeeze-in the repair during late daylight before the temps dropped back down below freezing here in north GA. My garage is too small for my truck! THANKS!!!
After contemplating short-cuts, I pulled the intake manifold/plenum to be as thorough and safe as possible. Because of your helpful response, and especially the photos and diagrams, I found the job to be much easier than I had at first thought it would be. As old as the truck is (and I will be updating my signature ASAP) you can imagine that there have already been a couple of repairs to the wiring harness. It took a while to figure out what had been done, and then re-work everything correctly. I bought new gaskets, which turned out to be paper and far inferior to the metal/rubberized gaskets already installed. So I cleaned up the old gaskets and re-used them with no problems.
Being old and short, the hardest part of the job was lying across the engine bay on an old yoga mat so I could actually reach the parts I needed to work on! It made me miss some of the old little roadsters I used to tinker with in my younger days. I only thought it hurt to lean over the engine!
After contemplating short-cuts, I pulled the intake manifold/plenum to be as thorough and safe as possible. Because of your helpful response, and especially the photos and diagrams, I found the job to be much easier than I had at first thought it would be. As old as the truck is (and I will be updating my signature ASAP) you can imagine that there have already been a couple of repairs to the wiring harness. It took a while to figure out what had been done, and then re-work everything correctly. I bought new gaskets, which turned out to be paper and far inferior to the metal/rubberized gaskets already installed. So I cleaned up the old gaskets and re-used them with no problems.
Being old and short, the hardest part of the job was lying across the engine bay on an old yoga mat so I could actually reach the parts I needed to work on! It made me miss some of the old little roadsters I used to tinker with in my younger days. I only thought it hurt to lean over the engine!
