Couple EFI to CARB swap questions...

A word of warning on EFI to carb swaps: don’t expect to pass emissions in any state that does comprehensive smog inspections, because it won’t happen. Be aware that you are violating several Federal laws concerning the removal of pollution control equipment. If you operate the vehicle on public highways and get caught by the Feds (doubtful, but possible) you could be subject to fines and imprisonment. You won't get any more power from a carb than you will from EFI.

The following information is intended for informational purposes only. Operation of a motor vehicle modified in such as manner as described below should be limited to off road use only.

Doing the swap: You must know how to read electrical diagrams and wire circuits properly to do the swap. Don’t take shortcuts or cut corners in the fabrication of the electrical or mechanical assemblies. If you do NASCAR quality work, the car will look good, run good and be as reliable as a carb’d car can be. Take pride in a job done with excellence.

If you are one of those few people who do excellent work, please disregard my negative comments. They are not intended for you.

Quality, quality, quality…
Some of the motivation of my negative comments about carb to EFI has to do with the quality of electrical workmanship. A lot of the wiring “repairs” that I have seen on the road and in the junkyard looks like road kill. The other part of my negative view stems from people who can’t grasp the operation and tuning of EFI. Carbs have their own set of requirements and some learning is required to get the best performance. Every car is different and each installation needs to be tuned to get the best performance. Putting an “out of the box carb” or one from someone else’s car isn’t the way to success. There is no auto compensation for small variations in carbs like there is for EFI. Just throwing a carb on a car because you won’t bother to learn how EFI works is a poor excuse.


Now that the rant is over, here’s some practical advice…

Do not use an EFI in tank fuel pump with a carb. You will never get the pressure/flow regulated properly. Either go full EFI or use a tank/fuel pump/fuel lines out of an 84 or earlier Stang. Fabricating your own setup is possible but there are some snags to overcome.

Do not attempt to leave the EFI in place in an attempt to control either the electric fuel pump or ignition. Doing so qualifies you for the “Road Kill Mechanics Award”.

If you try to use your current tank, you will need to pull the fuel pump out and fabricate a pickup tube & strainer sock to replace the fuel pump. Or you can have a sump fabricated and welded onto you existing tank. Many welding shops will not weld fuel tanks because of the dangers involved if the tank isn't purged properly.

You will need an external electric fuel pump unless you change the timing cover for one with the mechanical fuel pump mount on it. Rip all the EFI wiring out, and the computer controlled fuel pump won't work. You will need to add a relay & switch and wire in the existing inertia switch for an external low pressure electric fuel pump. Do not try to wire the fuel pump without the relay. The 15-20 amps the pump pulls will overload the circuit. This will take power away from other items on the same circuit or cause the fuse or fuse link to blow.



You will need to run some new fuel feed lines or braided hose. The 3/8" aluminum tubing works well, but you will need a flaring tool and bending springs to fabricate the lines. Braided hose is easy to run and route, but is much more expensive. It is about $3.50-$4.00 a foot plus the end fittings, which are $3-$4 each. Fabricating hose assembles can be difficult, but anyplace that makes hydraulic hoses can do it for you for an extra charge. See http://www.amazonhose.com for more information.

For stainless steel braided hose and fittings for automotive use:

See http://store.summitracing.com/egnse...el+hose&searchinresults=false&N=+115&y=6&x=23

http://www.jegs.com/webapp/wcs/stor...hall&searchTerm=stainless+steel+hose&x=18&y=4

See http://www.aeroquip.com/pages/performance.html for more information on High performance automotive hose products

AN fittings require a 37 degree flaring tool. A standard automotive or household plumbing tool is 45 degrees and cannot be used with AN flare fittings. If you do, the flare is subjected to too much stress when the fitting is tightened, and is likely to fail or leak.

See http://www.mscdirect.com/ , http://www.mcmaster.com/ or for the flaring tool you will need . Prices start at $75 and go up

http://www1.mscdirect.com/CGI/N2DRVSH?PACACHE=000000013509163


http://www.mcmaster.com/ctlg/DisplCtlgPage.aspx?ReqTyp=CATALOG&CtlgPgNbr=2252&term=Flaring


While you are at the electrical part, you'll need a Durspark or similar ignition system. The 85 Mustang GT 5 speed has a suitable Duraspark distributor with a steel gear compatible with the roller camshaft. The EFI ignition depends on the EFI sensors to advance the spark. Rip out the TPS and MAP/Baro sensors and the computer will have no idea of the proper ignition timing for best performance. Running a fixed timing setting is only for test purposes or for a race track only car. Don't try it on the street: the results will not be nearly as good as a properly setup Durspark or equal. Crane makes a really nice distributor for non-EFI applications. . See http://www.cranecams.com/index.php?show=browseParts&lvl=4&prt=127 for more information.

Tools needed:
Crimp tool for connector pins $9-$30 AutoZone, NAPA, Advance Auto Parts or other store
100-150 watt soldering gun (recommend WELLER 8200PK soldering gun kit 100/140W) $30 at Lowes or $40 at Home Depot
3/32”-1/8” rosin core electrical solder, 1/4 lb roll $6 at Ace Hardware, Home Depot or Lowes
Assorted sizes of heat shrink tubing. Buy long pieces and cut length to fit. It is cheaper that way. http://www.partsexpress.com/webpage.cfm?&WebPage_ID=346&CFID=169547&CFTOKEN=34300345
Hot air gun to shrink the tubing ($30-$40) Home Depot
Jeweler’s screwdriver kit $5 at Ace Hardware
Assorted automotive wire, 18-16 gauge 10’-20’ foot spools in different colors. $5 a roll at Advance Auto Parts.
Ford connector pins AutoZone, NAPA or other store $5-$10 for a kit of 10-12 assorted pins

You will have $110-$150 in materials and tools if you don't already have them.

The water temp and oil pressure signals feed from the sender to the main harness through the 10 pin EFI engine harness. To utilize these senders, you need to identify the wires and find a way to reconnect them to the main harness after the EFI engine harness is removed. You need a weatherproof quick connector to join the sender wiring to the main harness.

You will need to construct a wiring harness from the ‘85 carb distributor to the Duraspark box if you go Duraspark, or other distributor to coil wiring.
The voltmeter picks up its signal from the switched voltage present on the instrument panel, so you don’t need to worry about that.

The fuel tank gauge is also independent of the computer wiring.

AutoZone wiring diagrams

http://www.autozone.com/servlet/UiB..._us/0900823d/80/16/71/3c/0900823d8016713c.jsp for 79-88 model Mustangs

http://www.autozone.com/servlet/UiB..._us/0900823d/80/19/59/5a/0900823d8019595a.jsp for 89-93 model Mustangs

http://www.autozone.com/servlet/UiB..._us/0900823d/80/1d/db/3c/0900823d801ddb3c.jsp for 94-98 model Mustangs


How to solder like a pro - http://fordfuelinjection.com/?p=7 a must read for any automotive wiring job.

Soldering pigtails onto existing pins is road kill quality work as far as I am concerned. Take some time to study the way the Ford connectors are assembled and you will find that a small jeweler’s screwdriver will release the pins from the connector shell. New pins and a crimping tool are available from the Standard Motor Parts or Bendix Electrical parts line that the NAPA & Bumper to Bumper Auto Parts stores carry. Ask any auto parts store about Standard Motor Products or Bendix Electrical wiring parts. Those that carry them will be able to get the parts you need. AutoZone has a cheap kit with 10 pins for about $5. Just enough pins to leave you short when assembling a connector.

One of the interesting things about the Ford OEM wiring diagrams is that the connector shape on the drawing matches the connector shape in the car. That makes it easier to identify connectors and circuits. OEM Ford diagrams are available at for an 85 Mustang at http://www.helminc.com/helm/Result....edia=&mscsid=2M838NG3R5SR2MCS00A3HVE05T03C501 or can be found in the Chilton series of auto repair manuals for Mustangs.

The following is an excellent idea from a fellow Stangnetter who tackled the wiring plan the right way. He obtained the wiring diagrams from an 85 carb'd V8 Mustang and laid them out side by side with the diagrams from his car. He then traced out each circuit and the wire colors and connectors associated with them. After tracing the circuit and connectors for a circuit, he laid out the changes he needed to make. One circuit at a time made a difficult big job into many smaller easy to manage jobs.

if you want to get rid of the computer, MAF and harness Please email me at allenpul@hotmail.com I want to convert my 86 SD to MAF.

With the stock EFI wiring harness, the red/green wire is the power to the ignition coil. If you want to take power from the ignition switch for intion or other engine erquirements, here are a couple of diagrams that will help.

Diagrams courtesy of Tmoss & Stang&2birds

Alternator, ignition, etc.


Ignition Switch


See the following website for some help from Tmoss (diagram designer) & Stang&2Birds (website host) for help on 88-95 wiring http://www.veryuseful.com/mustang/tech/engine/

Ignition switch wiring
http://www.veryuseful.com/mustang/tech/engine/images/IgnitionSwitchWiring.gif

Fuel pump, alternator, ignition & A/C wiring
http://www.veryuseful.com/mustang/tech/engine/images/fuel-alt-links-ign-ac.gif

Computer, actuator & sensor wiring
http://www.veryuseful.com/mustang/tech/engine/images/88-91_5.0_EEC_Wiring_Diagram.gif

Fuse panel layout
http://www.veryuseful.com/mustang/tech/engine/images/MustangFuseBox.gif

Vacuum routing
http://www.veryuseful.com/mustang/tech/engine/images/mustangFoxFordVacuumDiagram.jpg

mustangman70 said:

Its a speed density car

jrichker Thanks for that post man!!!

Im still left in the dark about the vacuum lines...And where to hook the coil up though Is #1 "V power" a switched 12 volt source?

Click to expand...

Damn I got one of those now! LOL ;o) Thanks anyway.

if you are running the 6a box the coil will hook to the orange+ and the black- wires coming from it the small red going into the box is a switched 12v to activate thhe ignition anyway let me know ow it turns out i have a 93 coupe that is converted to carb

What you are asking about : running the holley pump from the factory harness. The answer is yes you run it that way. I have a wiring diagram somewhere that shows the wiring to go from efi to carb and use the factory relay and wiring. I'll look for it but fletchs 5.0 site has a lot of the info you need.

mjjj04: that would be great if you could find that.

Question that was danced around here:
I'm using my 6AL box and blaster coil/MSD distributor from my old mustang (65). What wire do you tap in to "swith on" the 6AL? (I know it has its own power wire (red), and ground, as well as tach pick up, and coil +/-, I dont rember the color of the "ignition hot" wire that you tap into the stock wiring with). I assume its a wire that would go to a + coil on a stock set up?

Putting the distributor back in is fairly simple. Pull #1 sparkplug, put your finger in the sparkplug hole,
crank the engine until you feel compression. Then line up the TDC mark on the balancer with the pointer
on the engine block.

The distributor starts out with the #1 plug wire lined up at about 12:00 with you facing it. Align the rotor
to about 11:00, since it will turn clockwise as it slides into place.

Align the distributor rotor up with the #1 position marked on the cap, slide the distributor down into the block,
(you may have to wiggle the rotor slightly to get the gear to engage) and then note where the rotor is pointing.
If it still lines up with #1 position on the cap, install the clamp and bolt. If not, pull it out and turn 1 tooth forwards
or backwards and try again. Put the #1 spark plug back in and tighten it down, put the clamp on the distributor,
but don't tighten it too much, as you will have to move the distributor to set the timing. Note that if it doesn't
align perfectly with #1 position, you can turn the distributor until it does. The only problem is that if you are too
far one way or the other, you can't turn the distributor enough to get the 10-14 degree optimum timing range.

At this point hook up all the wires, get out the timing light and start the engine. Set the timing where your car
runs best. Don't forget to disconnect the SPOUT jumper connector when you set the timing, and plug it back
in when you finish.

The HO firing order is 1-3-7-2-6-5-4-8.
Non HO firing order is 1-5-4-2-6-3-7-8

I've gotten away from the electrical part of build, and am now just getting back into it again. I found this thread, and my post in it, and I am still wondering what "ignition hot" wire you guys are tapping your 6AL boxes into? Is it the red/lt green wire that is in the harness/connector on the drivers side near the firewall? A picture would be even better.

obviously electrics is not my specialty

No one?

A search would have brought these up...





The red/lt green wire is the stock ignition coil power feed from the ignition switch

More info is available at Welcome to MSD Ignition

Already have those diagrams. And already have all my msd components wired together (not using a stock coil, or distributor). I just was wanting to make sure that the red/lt green wire coming out of the driver side harness was to the stock ignition coil. Thanks anyways for the diagrams.