Conversion from Fuel Injection to Carbureted, Need assistance please

I had recently purchased this 1985 Ford F-150 302 5.0 Fuel Injected truck, it died on me a month and half later. Found out that engine was not orginal, electrical equipment was rigged to make engine work for short time. Engine is orginally carbureted due to certain resources. The only way I can save her is to change her back to Carburetion. I know I need to change the Intake manifold, Carburetor (of course) and change to an electric fuel pump. I am not sure exactly what specifications the Intake manifold and/or Carburetor need to be in order for this to work? Not sure what else I need to change, someone mentioned to me about something called the Halifax Switch (HAVE NO CLUE WHAT THAT IS). Do I really need to change the fuel pump to another one with low pressure? Do I need to change the Distributor? Am I missing anything? :1zhelp:

Thanks for all your help
James

Any of the manifold/carb combinations for trucks of that era with a 302 should work, whether 2bbl or 4bbl, 351 manifold wont work, the 351 is about 3" wider. You may have to make up some linkages. Just stay away from the variable venturi carb, it wasnt heavy enuff to be a good boat anchor, but it made a pretty good paper weight. You will have to change the distributor to one with vacuum and centrifugal advance, the spark advance is controlled by computer on the one you have. I think that is what someone is referring to when they mentioned the "halifax switch", never heard of that one, but the distributors with the tfi ignition module had a "hall effect" trigger system instead of the armature/pickup coil assbly. Youll also need the duraspark 3 ign module to go with the dist if it wasnt left on the truck. Look on the driver side fender well, if youre lucky it and the harness are still there. If that engine was originally carbed, it should have a block off plate covering the mounting pad for the mechanical fuel pump. If it does you can use a mechanical or electric. But the high pressure pump for ther fuel injection will not work, it will have way more pressure than the needle and seat of the carb can handle. Just a universal pump with 5-7 psi will work. If they havent boogered up the wiring too much by cutting wires ect... you shouldnt have any trouble putting the ign system back in order. If they did, the simplest thing will probably be to get a dist with vacuum/cent advance( reman is around 50$ with core) and an Msd ignition unit, they are fairly simple to install.

I am just curious about the fuel pump, if I dont have the ability to put in a mechanical fuel pump that runs off the cam roller, how and where would I install the electric fuel pump. From what I know the fuel tank has a fuel pump on it. Thanks for all you help and information :cool:

First you need to determine what youre working with there. If someone rigged the fuel injection system on a truck that was carbed, it could be rigged several different ways. Look under the truck and see if theres an externally mounted high pressure pump , it would probably be under the drivers seat, mounted to the frame rail with the filter right behind it. If there is, theres also probably a low pressure transfer pump in the tank, or they could have mounted it externally too. They also could have only the frame mounted high pressure pump, or a high pressure pump in the tank. If the truck originally came with a carbed big block, the electric pump was in the tank i think. Check your fuel pressure and see what you have, and figure out what kind of pump you have first. You may have to change the pickup tube assbly in the tank and use a standard universal externally mounted low pressure pump. You can mount it under the hood or back at the tank(recommended by most pump mfgs). You only need around 5-7psi for the carb, the efi pumps have way too much pressure and will flood constantly.

http://viewmorepics.myspace.com/index.cfm?fuseaction=user.editAlbumPhoto&albumID=1288697&imageID=16319960&MyToken=cfd75716-69f4-4e02-ba78-73b5a5db7712Alright I found out that there is an external fuel pump on the right side of the eninge attached to the frame, it then runs back to the top of the fuel tank. Not sure exactly if there is one on top of the fuel tank. Its a mid-frame tank, I tried to look on the top but it was very difficult, all I could see was the 2 lines coming from the fuel pump that I explained about earlier. If it has that one external pump which according to the manual on AutoZone.com is a high pressure pump, would that be the only one? It didnt really explain that well on that website, dont have any other help with this, thanks. About checking the pressure, there is not a way I can check, since I can't turn the truck on, right?
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The fuel pump should power up when you turn the key on, not being able to see what you have and not knowing how it was rigged up, im kinda shooting in the dark. Look at the wiring harness back at the fuel tank , the wires that go up to the top of the tank. Does it have only two small wires, or two small and two larger( 12 or 14 ga) ? If it has only two small wires(sending unit) theres no pump in the tank, if it has 2 small and 2 large there probably is. See if the pump comes on when you turn the key on, if not check your fuses, relay(if they used one), inertia switch(if they used one). If the pump wont come on, You may be able to get it running when you find out where youre losing power to the pump. If youre just gonna switch it over to carb anyway, look at the wires on the tank, if its only got 2 small wires, disconnect the line going to the pump you have now, install a universal low pressure electric pump, make sure youre getting a good flow and you should be good to go. I like to wire one of the inertia switches in line with the pump. Its added saftey in case of a wreck or rollover ,itll kill the pump.

Alright, I tried what you said about turning it to the on position and yes you can hear the external pump that sits to the bottom right of the engine, I followed the lines and could feel the gasoline going through them (vibration) to the EFI. I went back down to the external fuel pump on the frame and followed it back the other direction to the tank, on the top of the tank, I found the wiring harness, which you were talking about. It does have 2 small wires and 2 large wires. The question now is what can I do about the pumps, my guess is that there is a low pressure fuel pump in the tank which than pumps to the external pump which would be a high pressure pump to the engine. So I wonder if I leave the fuel pump thats in the tank, which may possibly be a low pressure one and just remove the external one. What do you think?

I cant imagine why they have the frame mounted pump, and one up by the engine, unless the frame mounted pump is bad and they bypassed it. Anyway, you cant use those if they are high pressure pumps. If the pump in the tank is ok, check the fuel pressure on it. If its between say 4 and 7 or 8 # you can use it like it is. You might squeak by with 9 or 10, ive seen people run that much but it usually causes flooding. If its above 7 or 8 # you can use an adjustable fuel pressure regulator. Most auto parts stores should be able to get you one or you can get one from Summit Racing/Jegs. You need one thats adjustable between 4-10 # or somewhere therabouts. OR, you can drop the tank, change the pickup tube assbly to one made for a carbed engine and install a universal electric like we talked about.

Just for the yucks, boys, just for the yucks:

"electrical equipment was rigged to make engine work for short time"

What, for a month and a half? How would you (or anyone) rig an electrical system so it worked for a couple of months?

The mechanic that looked it over for 2 days said that it was it was rigged and what was rigged just went out. I have had my friends look it over and they cant see anything wrong with it. Personally I dont think it was rigged and that something in the wiring just burnt out or something. Now I do know that both fuel pumps work and that there is fuel getting thru the lines. Its just when they get to the fuel injectors, something goes wrong, now I am not sure if it is what controls the fuel injectors (tells them when to spray) or what. My biggest problem is that I cannot seem to find a wiring diagram for the fuel injection system, If anyone knows what and where controls the fuel injectors please let me know, Thanks

So far we been talking mostly about converting to a carb, thats what you originally asked about, we havent really talked about troubleshooting what you have now. You need to check the fuel pressure, just because the pumps come on and you have fuel in the lines doesnt mean you have enough. It could be as simple as a clogged filter. Those systems need around 30psi at idle, anything less than around 25psi and most wont even start. Check the spark to see if youre getting a good hot spark, spray some carb cleaner in the intake and see if it will start(dont use ether). If you want to troubleshoot what you have and get it running with fuel injection, thats a different ball game.