wiring problems
Post Fiend
Joined: Jul 2004
Posts: 8,786
Likes: 28
From: Northern California
It all depended on what motor the truck came with, the 4.9 started in 84. 87 was when most, (all?), went EFI. But they had the Feedback carb/TfI computer setup before that. The harness your describing sounds just like the computer harness on my 4.9. I don't know enough to tell you what motors did or didn't come with computers that year but a lot of people on here do. If you only have the chock wire going to your carb then it would be a DSII ignition probably, and should have a vacuum dizzy if they did the complete change over. But I'm betting your truck came with a computer, and probably still has it mounted under the dash. I'm thinking the 2 wires still connected are gauge sensor wires.
California State 5.0L and 5.8L was EEC-III, Duraspark-III in 1980. And the 4.9L was MCU (microcomputer contol Unit) DS-II in 1981.
Originally Posted by 84F150XLT
it has a 2v carb on it now..and i know the smog crap was bypassed. i am going with whisler's explanation, that someone did a conversion and didnt pull the harness. i like that better then he just hacked up some wires..haha
Laughing Gas
Joined: Aug 2010
Posts: 983
Likes: 49
From: Northern Kentucky
As far as the ones to the computer , it is a bunch, but they are all in one harness. I "think" there are two harnesses that go through the firewall, one to the computer and one for everything else.
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Freshman User
Joined: Feb 2012
Posts: 41
Likes: 0
From: Manitoba,Canada
turns out there is a computer uder the dash...my teacher said something probably we nt wrong with the efi so for simplicitys sake the PO just swapped manifolds over to a carbourated one? sound reasonable?
now should i just tuck all them wires where they were or yank em and pull the computer??
now should i just tuck all them wires where they were or yank em and pull the computer??
Laughing Gas
Joined: Aug 2010
Posts: 983
Likes: 49
From: Northern Kentucky
'84 F150, 351W would not have been fuel-injected, but did have the electronic feedback carb and computer controlled ignition (TFI). The feedback carbs were notoriously bad for not idling properly and being difficult/impossible to adjust.
Probably the PO did what I did and switched back a few years to the standard 2150 carb and Duraspark II ignition. This eliminates the need for the computer for carb and ignition, but with those two things out of the system the computer wouldn't know what was going on with the emissions. So I (and probably your PO) just pulled all the emissions stuff.
But then why leave all those useless wires and vacuum hoses in the engine compartment. Here's where my route differed from your PO; I pulled all the wires through the firewall and disconnected them from the computer and also removed the computer altogether. Your PO must have decided on the more expedient route of hacking the wire harness at the firewall and leaving the computer were it was.
To each his own, as they say.
As to your question, I would trace the two wires that you say are still connected and see were they lead. If they go to the computer,then they are not needed, yank them. If they go someplace else you better verify what they are doing, before you do anything you may regret. I like things as uncluttered as possible, that's why I pulled the wires and computer completely.
Probably the PO did what I did and switched back a few years to the standard 2150 carb and Duraspark II ignition. This eliminates the need for the computer for carb and ignition, but with those two things out of the system the computer wouldn't know what was going on with the emissions. So I (and probably your PO) just pulled all the emissions stuff.
But then why leave all those useless wires and vacuum hoses in the engine compartment. Here's where my route differed from your PO; I pulled all the wires through the firewall and disconnected them from the computer and also removed the computer altogether. Your PO must have decided on the more expedient route of hacking the wire harness at the firewall and leaving the computer were it was.
To each his own, as they say.
As to your question, I would trace the two wires that you say are still connected and see were they lead. If they go to the computer,then they are not needed, yank them. If they go someplace else you better verify what they are doing, before you do anything you may regret. I like things as uncluttered as possible, that's why I pulled the wires and computer completely.
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z1121jack
1948 - 1956 F1, F100 & Larger F-Series Trucks
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May 13, 2010 09:17 PM
