85 460 dual tanks

[Haystack]

I picked up an old 85 a guy was using as a farm truck. The guy cut a ton of wires, and burned a bunch of the wiring harness up just leaving bare wires hanging.

Front tank didn't work, previous owner hacked in a switch and wire to the rear tank, of course cut every wire at the frame rail near the front tank. I have fixed the tail lights and am now going after the fuel system.

Carb leaked everywhere, float bowls, accelerator pump, and the power valve. I took it apart, reset the float, regasketed everything and swapped out the power valve, but now I have black smoke at idle. 4180 carb was modified with corner idle adjustment screws, all the linkage is disconnected except for the primary throttle shaft. I found and added the linkage to the accelerator pump from the junk yard, but haven't gotten around to the secondaries yet.

I re-set the timing and idle screw, turning the corner idle adjustment screws just give me clouds of black smoke, so I checked the fuel pressure and I am getting 11psi at the fuel line.

Is there supposed to be a regulator? I know there is a step down using a resistive wire, I am going to work on splicing that back together next, but I need to figure out why I am getting such high fuel pressure. I can see two lines, one fuel in, one return, the return line seems to loop down right before the carb, is there a regulator there? I have not verified that the return line is hooked up, and I could see this being the whole problem, but the diagrams do not show any regulator at all anywhere in the system. This is the dual tank system, and the selector valve and all wiring has been bypassed to a hot wire off the fuse box.

Sorry, I am an efi guy, and this is my first ever carb. I have and currently own two 86 thunderbirds with sefi 302's, so I am pretty well versed in old fords, just never had a carb before.

[Gary Lewis]

There is no true regulator. If you have a return line then you have the hot-fuel handling system which uses a small orifice to return some fuel to the tank. But those sometimes get plugged since the orifice is so small.

And yes, you are supposed to have a resistance in the harness to drop voltage to the pump when in Run. It gets full voltage in Start. So if that's been bypassed then you have too much voltage.

But 11 psi is about twice what you should have at the carb. I don't know what a Holley can stand, but a Carter/Edelbrock has problems above 6 psi - and the problem is high fuel level and rich running.

You could put a true return-style pressure regulator in, but you should find out why you have such high pressure first.

[85lebaront2]

I will almost be willing to bet it has the wrong in-tank pumps. The originals are centrifugal pumps that deliver at 5-7 psi. The EFI primary pumps are stronger and probably do produce 11 psi.

What you have is called a "Hot Fuel Handling Package" it was developed originally for the Ambulance cab and chassis trucks because they would vapor lock when sitting still and running. Since the tanks are identical for the EFI and hot fuel handling package, very likely someone installed the wrong pumps.

Here is a link to the 460 fuel systems: https://www.garysgaragemahal.com/460-fuel-systems.html

It covers the system pretty well. When I needed a pump for mine only Pep Boys actually had a listing for it.

[Haystack]

Crawled under it, it has a generic fuel pump with only a part number zip tied to the frame. All the wires are cut going to the fuel tanks, as well as the lines. They jammed a 1/4" barbed fitting into the nylon lines.

Debating on if I want to add a mechanical fuel pump (they are around $20) and just bypass the mess this guy made.

In the next few days, I am going to try to test the fuel take selector valve to see if it functions. Front take smells really bad, I may drop that out and see what's inside of it.

I got 7mpg driving it home, really don't want to only have a single tank if I can help it, but not sure if I want to replace 3 fuel pumps and the selector valve before I get the truck running.

Thanks for the replies and links, I know what I need to do now, thanks!

[Gary Lewis]

Crawled under it, it has a generic fuel pump with only a part number zip tied to the frame. All the wires are cut going to the fuel tanks, as well as the lines. They jammed a 1/4" barbed fitting into the nylon lines.

Debating on if I want to add a mechanical fuel pump (they are around $20) and just bypass the mess this guy made.

In the next few days, I am going to try to test the fuel take selector valve to see if it functions. Front take smells really bad, I may drop that out and see what's inside of it.

I got 7mpg driving it home, really don't want to only have a single tank if I can help it, but not sure if I want to replace 3 fuel pumps and the selector valve before I get the truck running.

Thanks for the replies and links, I know what I need to do now, thanks!

The fuel systems on the Bullnose trucks were an experiment Ford was conducting to see what would work, and most of them failed. Not until several years later did they stumble on one that works and for which you can buy parts. But that system is for the EFI trucks and, while it can be made to work for a carbed engine, it is serious overkill. Been there, done that.

Parts for the dual-tank system with a mechanical pump are hard to find and expensive - as well as troublesome. If I were in your shoes I'd consider the aftermarket 38 gallon rear tank and a mechanical pump.

[85lebaront2]

Crawled under it, it has a generic fuel pump with only a part number zip tied to the frame. All the wires are cut going to the fuel tanks, as well as the lines. They jammed a 1/4" barbed fitting into the nylon lines.

Debating on if I want to add a mechanical fuel pump (they are around $20) and just bypass the mess this guy made.

In the next few days, I am going to try to test the fuel take selector valve to see if it functions. Front take smells really bad, I may drop that out and see what's inside of it.

I got 7mpg driving it home, really don't want to only have a single tank if I can help it, but not sure if I want to replace 3 fuel pumps and the selector valve before I get the truck running.

Thanks for the replies and links, I know what I need to do now, thanks!

Here is the link to the pumps on Rock Auto. If you look at the pictures you will see they are centrifugal. I used my truck as a reference, it's an 86 crew cab dually now converted to MAF/SEFI from carbureted.

https://www.rockauto.com/en/catalog/ford,1986,f-350,7.5l+460cid+v8,1126358,fuel+&+air,fuel+pump,6256

[Haystack]

I pretty much decided on just adding the mechanical pump and the bronco 38 gallon tank, however...

This is a "stripped chassis" truck with duals and I guess that means it has narrower frame rails and the 38 gallon tank may not fit. I know it's an "over 8500gvwr" truck, but the door tag is almost illegible.

This is a bucket truck with a utility bed on it, and I like the idea of the dual tanks both for range and as a back up, the bucket is powered by a PTO off the transmission, so if you ever run out of gas, the bucket also stops working. I am going to mess with it tomorrow and measure the frame rails to see if it really is narrower. If I have to buy new parts, I think I would rather have the 38 gallon rear tank and a front (16 or 19 gallon?) tank for both range and a backup/safety. When I get this truck working properly, I am going to be putting it to work, and the capacity/range would definitely be a benefit. Seems like this thing has around a 5:13 gear with no overdrive, so every gallon is going to count!

Funnily enough that you guys mentioned the newer efi setups, my next project will be getting the dual tanks working again on my dad's 91 e-250 EFI 460. It's not in bad shape for the year, but gas has been over $4 a gallon out here, so my dad rarely takes it out more often then an annual dump run. I may just convert it over to the newer efi type setup fuel system since any extra or unused parts could be used or shared for troubleshooting when I get around to the van.

I got all the wiring and lights swapped out for the tail lights, replaced all the bulbs, decided I was going to take it around the block, and the clutch died on me, feels like I don't have quite enough travel on it, so now I am messing with the hydraulics.

[85pig]

The fuel systems on the Bullnose trucks were an experiment Ford was conducting to see what would work, and most of them failed. Not until several years later did they stumble on one that works and for which you can buy parts. But that system is for the EFI trucks and, while it can be made to work for a carbed engine, it is serious overkill. Been there, done that.

Parts for the dual-tank system with a mechanical pump are hard to find and expensive - as well as troublesome. If I were in your shoes I'd consider the aftermarket 38 gallon rear tank and a mechanical pump.

Just wondering out loud, but if this truck came stock with an electric pump, would it have a fuel pump eccentric on the cam gear?

[Gary Lewis]

Just wondering out loud, but if this truck came stock with an electric pump, would it have a fuel pump eccentric on the cam gear?

That's a good question, but I think in 85 they still had an eccentric on all the engines. Or at least a place for the pump on the block as the eccentric can be added.

Haystack - You have to decide up front if you want to go with the EFI-style tanks and fuel delivery modules as the FDMs have a tab that goes into a slot in the tank, and it is in a different place on the EFI tanks.

But if you do you can still run a carb. I ran the FDMs with two fuel pressure regulators. First I had a return-style regulator, but by itself the pressure was bouncing all over the place and I worried that the carb couldn't handle that. So I added a dead-head style regulator and that smoothed the pressure out nicely.

And I also had to install a MeterMatch to convert the sending unit range to something that works with the Bullnose gauges. But now I have a system that is tried and true, AND is available off the shelf at many parts stores.

[85lebaront2]

That's a good question, but I think in 85 they still had an eccentric on all the engines. Or at least a place for the pump on the block as the eccentric can be added.

Haystack - You have to decide up front if you want to go with the EFI-style tanks and fuel delivery modules as the FDMs have a tab that goes into a slot in the tank, and it is in a different place on the EFI tanks.

But if you do you can still run a carb. I ran the FDMs with two fuel pressure regulators. First I had a return-style regulator, but by itself the pressure was bouncing all over the place and I worried that the carb couldn't handle that. So I added a dead-head style regulator and that smoothed the pressure out nicely.

And I also had to install a MeterMatch to convert the sending unit range to something that works with the Bullnose gauges. But now I have a system that is tried and true, AND is available off the shelf at many parts stores.

Even the later EFI engines still have the eccentric as it serves as the retainer for the cam gear.