1986 Ford F250 302 EFI Delete

[Phillip G.]

As you may have already seen. I'm trying to finish an EFI delete that someone else started and need some help from anyone that has done this already. My truck is a 4 speed, not AOD. 1. Can I just pull fuel from the factory fuel tank using a mechanical pump with fuel lines connected to the factory tank pump with the electric tank pump unplugged and the frame rail high pressure pump removed? My truck is a single tank model. 2. What wires I can cut out of the old EFI engine harness?

[Gary Lewis]

I think you can pull through an EFI pump, but I've not tried it.  However, the plug you are talking about has both power to the pump as well as the signal to the fuel gauge.  So if you unplug it you won't have a working gauge.

The schematic below shows how that should have originally been wired, so you could remove the BR/W wire on the front tank and/or the R wire on the rear tank to keep from providing power to the pump and still have the gauge.

[Phillip G.]

Gary Lewis wrote

I think you can pull through an EFI pump, but I've not tried it.  However,
the plug you are talking about has both power to the pump as well as the
signal to the fuel gauge.  So if you unplug it you won't have a working
gauge.

The schematic below shows how that should have originally been wired, so you
could remove the BR/W wire on the front tank and/or the R wire on the rear
tank to keep from providing power to the pump and still have the gauge.

Quoted from:
https://forum.garysgaragemahal.com/1986-Ford-F250-302-EFI-Delete-tp148614p148618.html


Thanks Gary! I also just realized this should've been posted in the "Projects" section. I just have the front tank so I'll try disconnecting that wire. However, my gauge isn't reading correctly now. Hopefully the engine has the fuel pump eccentric. It does have the factory delete plate on the engine block.

I'm pretty much stuck with going forward with the EFI delete. The guy I got it from has already put an intake and carburetor on it and didn't have the original setup. He's got it rigged to run but it's all a mess. Wiring spliced, vacuum hoses plugged off etc. Is there a complete wiring diagram for say an '84 carbureted model truck?

[Phillip G.]

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[Gary Lewis]

Here's your pic.  You have to use the Insert Image button above.

And do you want me to move it to the Projects section?

[Phillip G.]

Yes, move it please. I saw where a guy named Waine did one. Maybe he can help too. I figured the insert image option.

[mat in tn]

stop and consider this. first off was the truck originally an efi? I know you already said so but I'm playing Matlock for a minute. did the truck have an in-tank pump matched with a high-pressure rail pump? if so, you can use the in tank (low pressure) pump to feed a carburetor. I have done many this way and it works perfectly. in some cases, you may need to add a fuel pressure regulator. but not always. this has a couple benefits. one is that all of the wiring stays as is except for the deletion of the rail pump. next is that you keep the return line compatibility which is very similar to fords "hot fuel" circuit on the 460. third, why buy a pump when you already have one? and you keep the safety switch intact under the glove box to shut off the pump in the case of a hard impact.

[Gary Lewis]

Moved.

[mat in tn]

has anyone heard from Wayne? before I moved from mid tenn I had the chance to meet with him and work with him on his truck one day. a while after that he decided to drop the efi and go carburetor. I have not talked to him really since I moved.

[ArdWrknTrk]

mat in tn wrote

stop and consider this. first off was the truck originally an efi? I know you already said so but I'm playing Matlock for a minute. did the truck have an in-tank pump matched with a high-pressure rail pump?

By the '86 MY all 302's were EFI...

[Phillip G.]

Hey Matt! Yes, originally I considered using the tank pump. However it reads the resistance backwards which of course gives a false reading at the gauge. So, I'd have to buy a pump regardless but I do like that idea.

I assume you're saying to just keep the wiring as it is in case I ever wanted to go back to the EFI setup. If so, that's not a bad idea either. I would like to use the original fuel lines as you pointed out too. I was just thinking that a mechanical pump would put the psi where it needed to be.

The guy that started this has all the engine bay wiring harness out of the loom and it's literally a spider web... lol. I've also got to put an inline ballast resistor going to the ignition coil. It has the old cylinder ignition coil and points distributor. I need to see where he's getting the coil power from because it's burned up a coil already that he installed.

[Gary Lewis]

There is a solution to the backwards reading on the fuel gauge - MeterMatch.  It supposedly converts any sender to any gauge, but I'm using one to convert a 96 sender to a Bullnose gauge.  Works great.

[ArdWrknTrk]

Because the way EFI coils are wired they get full power all the time, instead of just while cranking.

There's too much dwell for a DS-II coil, instead of the little square coil the FI trucks have..

[mat in tn]

I'm not sure about something. is the truck not an 86? is the fuel pump not an 86? the sender for the gauge is not affected if it has all original wiring. then you are just using the pump that you already have.

[Phillip G.]

Yes, 5/1986 production date. It has original wiring to the tank pump that of course is a pump/sender combination. I removed the tank pump and manually raised the float upwards and it went to E at the gauge. Manually move the float down all the way and it goes to F at the gauge.

[Gary Lewis]

So someone put a later sending unit in a Bullnose.  That's where the MeterMatch comes in.

[Phillip G.]

Yes Jim. The truck doesn't even have an ignition control module. The wiring is hacked and someone is feeding a cylinder DS II coil & points distributor from somewhere which I'll trace down when I have time. By the way, I do have an '82 F250HD with the heavy rear axle. It was a 351M truck.

[Gary Lewis]

Just FYI, an '82 F250 should have come with a 400, not a 351M.  The M was last used in '81 and the 351W was introduced for '82.  But the 400 was retained for '82 and then replaced by the re-introduced 460 in '83.

[Phillip G.]

I guess so Gary. Just another reason to go back all mechanical and older ignition system with this hack mess. Thanks for letting me know that '82 was a 400cid. I've been a '67 thru '71 Ford truck guy for 42 years. Anymore, I get the later years mixed up. But, I'm here to learn the Bullnose trucks.

[mat in tn]

so, you have more of a mixed bag already. that can muddy the waters a bit. even still, getting a fuel pump module for an efi 1986 should be a clean option. or getting a sending unit for an 86 with the 4.9 will give you the correct readings and allow an external pump whether mechanical or electric. staying with an 85/86 year should fit the tank as earlier tanks had a smaller hole.