4.9L EFI - CARB Conversion
Lead Driver
Joined: Jun 2021
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Well I DID use a one wire GM HEI distributor for my conversion (works GREAT!). I think these EFI to Carb conversions will be around for a LONG time, especially since you can't get a new computer for these old EFIs (I think). And I am so happy with this conversion because it doesn't randomly stall (SO DANGEROUS)! I just saw an ad for a 93 Jeep Cherokee that "starts, runs a bit, then stalls". I'm thinkin "Hmmm, I wonder if I could convert THAT one over?" I'm basking in the glow of this success ...
but not everything is powered by a pushrod 3.8l v6 that descends from a buick small block, sadly.
But I am in a similar boat in the future, my trucks wiring is degrading and the truck has way too many 1 year only parts.
the day it starts to become short to power city and NLA ripperoni you cant get that part anywhere nerd (self monologue) then the intake and distributor and a carburetor are going on and simple custom wiring where needed and an aftermarket E4OD controller.
Lead Driver
Joined: Jun 2021
Posts: 5,219
Likes: 805
In my 3800s Thats 90% of the time a crank sensor easy peasy job
but not everything is powered by a pushrod 3.8l v6 that descends from a buick small block, sadly.
But I am in a similar boat in the future, my trucks wiring is degrading and the truck has way too many 1 year only parts.
the day it starts to become short to power city and NLA ripperoni you cant get that part anywhere nerd (self monologue) then the intake and distributor and a carburetor are going on and simple custom wiring where needed and an aftermarket E4OD controller.
but not everything is powered by a pushrod 3.8l v6 that descends from a buick small block, sadly.
But I am in a similar boat in the future, my trucks wiring is degrading and the truck has way too many 1 year only parts.
the day it starts to become short to power city and NLA ripperoni you cant get that part anywhere nerd (self monologue) then the intake and distributor and a carburetor are going on and simple custom wiring where needed and an aftermarket E4OD controller.
Fleet Mechanic
Joined: Nov 2011
Posts: 1,823
Likes: 43
From: New York
On a related note, I was sorta surprised to see a EEC-IV PCM on the '86 4.9 I recently saw at the junkyard. I guess even though they were carb, there was still an element of computer control going on - probably choke control and maybe even ignition mapping? I'd assume for anyone doing a carb swap the typical approach is to do away with that.
Lead Driver
Joined: Jun 2021
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Rebuilt PCM's are very much readily available, that's not really a valid reason to go carb.
On a related note, I was sorta surprised to see a EEC-IV PCM on the '86 4.9 I recently saw at the junkyard. I guess even though they were carb, there was still an element of computer control going on - probably choke control and maybe even ignition mapping? I'd assume for anyone doing a carb swap the typical approach is to do away with that.
On a related note, I was sorta surprised to see a EEC-IV PCM on the '86 4.9 I recently saw at the junkyard. I guess even though they were carb, there was still an element of computer control going on - probably choke control and maybe even ignition mapping? I'd assume for anyone doing a carb swap the typical approach is to do away with that.
New User
Joined: May 2020
Posts: 12
Likes: 6
I DID put a rebuilt PCM on there, and still had the stalling trouble. When you stall, and you lose power steering while taking a left turn in front of bearing-down-traffic, then you will know. Also, the thing is now EMP proof (aside from the distributor module, of which I carry a spare in a Faraday cage).
Lead Driver
Joined: Jun 2021
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Ive grenaded a transmission in that exact scenario just didnt stall but the car still jerked a little forward I was able to inefficiently keep moving but ive also had steering that checked out when it felt like and come back when it felt like
Laughing Gas
Joined: Dec 2005
Posts: 904
Likes: 115
From: Laurel, MS
I'm not sure when Ford changed from EEC-III to EEC-IV, but my '91 F150 had a 4.9L with EEC-IV (prior to my engine swap).
Fleet Mechanic
Joined: Nov 2011
Posts: 1,823
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From: New York
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Fleet Mechanic
Joined: Nov 2011
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From: New York
Then it's highly likely you had some other issue unrelated to the PCM. I'm not condemning you from going carb, just saying that PCM availability is not the reason to do so.
I've got a stack of five known-good PCM's here I can swap in as needed. I have found that the later ('94/'95) PCM's seem to have held up better with time. The worst offenders seem to be the ones from '90 - '93. I've got seven of those here all with failed capacitors. I keep saying I'm going to try my hand at soldering in new caps but haven't yet gotten to that project.
I've got a stack of five known-good PCM's here I can swap in as needed. I have found that the later ('94/'95) PCM's seem to have held up better with time. The worst offenders seem to be the ones from '90 - '93. I've got seven of those here all with failed capacitors. I keep saying I'm going to try my hand at soldering in new caps but haven't yet gotten to that project.
Lead Driver
Joined: Jun 2021
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this aint plugged into the EEC-IV test connecotr LOL Its 96 4.9. i even wrote 4.9 on the accumulator thing
Fleet Mechanic
Joined: Nov 2011
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From: New York
Lead Driver
Joined: Jun 2021
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not EVERYTHING there are quite a few exceptions such as the 1997 F250 460 is eec-iv unless california trucks were eec-v(I dont think so) also there was EEC-IV uses from ford until 2002,2003 the latests Ive heard and 2004 was the final year it would be remotely possible in light duty vehicles
Fleet Mechanic
Joined: Mar 2014
Posts: 1,926
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From: Saskatchewan Canada
I DID put a rebuilt PCM on there, and still had the stalling trouble. When you stall, and you lose power steering while taking a left turn in front of bearing-down-traffic, then you will know. Also, the thing is now EMP proof (aside from the distributor module, of which I carry a spare in a Faraday cage).
New User
Joined: May 2020
Posts: 12
Likes: 6
This is gonna veer off topic, but my answer is "no, the metal casing around a typical EEC in NOT an effective Faraday cage because there are multiple feed-throughs that offer windows of opportunity for the pulse to penetrate, not to mention other holes in the casing". I encourage everyone interested to investigate how to make and test a Faraday cage, and THAT is the last I will say about it on this forum.
Lead Driver
Joined: Jun 2021
Posts: 5,219
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This is gonna veer off topic, but my answer is "no, the metal casing around a typical EEC in NOT an effective Faraday cage because there are multiple feed-throughs that offer windows of opportunity for the pulse to penetrate, not to mention other holes in the casing". I encourage everyone interested to investigate how to make and test a Faraday cage, and THAT is the last I will say about it on this forum.
im saying that but its funny because im usually the nerd
