Big Blue's Transformation

[85lebaront2]

Bill - Yes, the 5.0L EFI's wiring is nice as simple, as shown below:

Not so the 7.5L's, which is what I have. And this is only half of the wiring diagram as it takes another page to show the pump circuits. So I'm going to replace the Tank Selector Valve in the diagram below with a relay.

What is disappointing is that at first glance it looked like every one of the circuits is available in C127. But on closer inspection I found the "F150-350 only" note that shows that Big Blue's sender wiring goes straight to the tank selector valve. So I'll extend the wires up to the firewall area.

Is the actual tank selector switch the same, just wired differently? To me adding a relay, if it isn't needed is just over complicating things.

Looking at the 5.0L EFI and the 7.5L hot fuel handling diagrams, both show a double pole double throw no off switch with 6 pins 1 - 3 for one side and 4 - 6 for the other. It might involve rewiring the switch so that it will (a) run the pumps and (b) select the appropriate sender.

On the EFI, pin 1 is front tank pump, 2 is feed, 3 is rear tank pump, 4 is front sender, 5 is dash gauge, 6 ir rear sender.

On the 7.5L, pin 1 feeds the tank selector valve motor to drive it to the front tank position and it in turn, changes the sender. Power is fed in through pin 2. Pin 5 provides the ground for the selector valve motor to pin 4 through it's internal diode. To select the rear tank, the switch now powers pin 3 and grounds pin 6 causing the motor to drive the valve and it's internal switch to the rear tank.

If you take the power in and leave it on pin 2, use pin 1 for the front pump (red wire) and pin 3 for the rear pump (brown with white wire) then connect the dash gauge wire (yellow with white) to pin 5 and connect the front sender (dark blue with yellow) to pin 4 and rear sender (yellow with light blue) to pin 6 everything will work as designed and no extra relay is needed.

At the tank selector valve there are 5 wires, 3 of them will need to be extended to the inside of the cab to the tank selector switch. This is far easier (and cheaper) than finding a completely weather proof relay and socket and wiring it in place of the valve.

We had to make a somewhat emergency run to Virginia Beach and Norfolk so did not get you the pictures of the lines and filter mount.

[Gary Lewis]

Is the actual tank selector switch the same, just wired differently? To me adding a relay, if it isn't needed is just over complicating things.

No, they aren't, as you can see below. Two different part numbers for the 460's and diesels with dual tanks (E4TZ-K) to all the others (E4TZ-M).

But, you have a very good point! So I'm off to figure out how they differ in wiring. Perhaps a relay isn't needed!?!?!

[Gary Lewis]

Is the actual tank selector switch the same, just wired differently? To me adding a relay, if it isn't needed is just over complicating things.

No, they aren't, as you can see below. Two different part numbers for the 460's and diesels with dual tanks (E4TZ-K) to all the others (E4TZ-M).

But, you have a very good point! So I'm off to figure out how they differ in wiring. Perhaps a relay isn't needed!?!?!

Good idea, Bill. But it won't work as the switch in the HVAC panel is entirely different. Here's the one for the other trucks, and you'll see that the wires from the senders (DB/Y & Y/LB H) come up to the switch. And there are two switches in one - one to control the selector valve and the other to select the sender to present to the gauge.

Unfortunately that's not what I have. In mine there's a DPDT switch which runs the motor in the selector valve, and there are contacts in that valve that select the sender to present to the gauge. IOW, in some cases the senders come into the cab to the tank switch, but in my case they end below the driver on the frame rail.

So all I have is power with with to select the sender to present to the gauge. Looks like I need a relay.

[ArdWrknTrk]

Good idea, Bill. But it won't work as the switch in the HVAC panel is entirely different. Here's the one for the other trucks, and you'll see that the wires from the senders (DB/Y & Y/LB H) come up to the switch. And there are two switches in one - one to control the selector valve and the other to select the sender to present to the gauge.

Unfortunately that's not what I have. In mine there's a DPDT switch which runs the motor in the selector valve, and there are contacts in that valve that select the sender to present to the gauge. IOW, in some cases the senders come into the cab to the tank switch, but in my case they end below the driver on the frame rail.

So all I have is power with with to select the sender to present to the gauge. Looks like I need a relay.

Why the sad face?

It's not difficult to implement.

[Gary Lewis]

Why the sad face?

It's not difficult to implement.

Because I was hoping Bill was right and it would be so simple. But, as it turns out it isn't quite that simple. So, I think I'm going to use the wires coming down to the switching valve in reverse and send the sending units' output back up them to the to-be relay. The color codes won't be right, but it'll work.

Speaking of just making it work, I pulled a whole lot of tape and convolute off trying to find S160, which is where the resistance wire going to the fuel pumps in Run originates. I need to bypass that to give the pumps full battery voltage in Run, but think I'm going to cheat and just jumper from the Tank Selector Relay, which does have battery voltage in Run, to the Fuel Pump Cutoff Relay. Thoughts?

Also, I got the Holley fuel pressure regulator in, so I'm ready when the time comes to install that. However, I still haven't found the 5/16" and 3/8" male quick disconnect to barb connectors I'm looking for to let me use the quick disconnects with the fuel pressure regulator and carb. I may improvise, but if someone has suggestions please pass them on.

Last, I cut the Bullnose fuel tank connectors off and grafted the new pigtails on.

[85lebaront2]

Why the sad face?

It's not difficult to implement.

Because I was hoping Bill was right and it would be so simple. But, as it turns out it isn't quite that simple. So, I think I'm going to use the wires coming down to the switching valve in reverse and send the sending units' output back up them to the to-be relay. The color codes won't be right, but it'll work.

Speaking of just making it work, I pulled a whole lot of tape and convolute off trying to find S160, which is where the resistance wire going to the fuel pumps in Run originates. I need to bypass that to give the pumps full battery voltage in Run, but think I'm going to cheat and just jumper from the Tank Selector Relay, which does have battery voltage in Run, to the Fuel Pump Cutoff Relay. Thoughts?

Also, I got the Holley fuel pressure regulator in, so I'm ready when the time comes to install that. However, I still haven't found the 5/16" and 3/8" male quick disconnect to barb connectors I'm looking for to let me use the quick disconnects with the fuel pressure regulator and carb. I may improvise, but if someone has suggestions please pass them on.

Last, I cut the Bullnose fuel tank connectors off and grafted the new pigtails on.

If you look at the switch for the hot fuel handling package (which Darth had) it has 6 pins and is a DPDT no center off switch if you uses one side of the switch for the pumps and the other side for the gauge senders it will work fine, same as the 1990-97 system does. It will require taking the two gauge sender wires at the tank selector valve and extending them to the switch, and moving the gauge wire to the center pin on the other side of the switch. Why complicate things with an additional relay?

[Bruce moose4x4]

Here's the plan - everything will be new. I'm ordering:

• Dorman 800-072: 25' of 3/8" fuel line

• Dorman 800-082 3/8" Steel To 3/8" Nylon Fuel Line Connector: There are two in a package and I need five, but I have one on an 18" piece of tubing, so will use that one from the supply wye to the fuel filter. So I'm ordering two packages.

• Dorman 800-082 5/16" Steel To 3/8" Nylon Fuel Line Connector: I need three of these so am ordering two packs.

• Male Disconnects to fuel hose: I'm still looking for the male part of the disconnects, which I think is called either a Bundy or SAE, to a 3/8" hose barb. I need one in 3/8" male and one in 5/16" male for the supply and return lines respectively. I want these to clip into the new lines on the back of the bell housing to go to the fuel pressure regulator while I'm running the carb. But have not yet found them.

• DORMAN 800-301 Fuel Line Repair Tool

It's not a hose barb, but this might work.

https://www.amazon.com/AGS-FLRL155-Fuel-Line-Adapter/dp/B01KLG7F9G

5/16 is flrl150 AGS

[Bruce moose4x4]

It's not a hose barb, but this might work.

https://www.amazon.com/AGS-FLRL155-Fuel-Line-Adapter/dp/B01KLG7F9G

5/16 is flrl150 AGS

If you didn't want to use just a hose clamp on those above you could use these. But it is several fittings but if it is temporary? It might be good enough.

Then you could use an AGS CFF-6B and a FHF-14B for the 5/16

3/8 would be CFF-8B and a FHF-13B

These are a compression tube to female pipe 1/4 then a male hose barb.

[Gary Lewis]

If you didn't want to use just a hose clamp on those above you could use these. But it is several fittings but if it is temporary? It might be good enough.

Then you could use an AGS CFF-6B and a FHF-14B for the 5/16

3/8 would be CFF-8B and a FHF-13B

These are a compression tube to female pipe 1/4 then a male hose barb.

Bruce - I think I understand, but let me make sure.

Option 1 is to use the fuel line adapter shown below and slip a hose over it, placing a clamp in the recess?

Option 2 is to use that adapter with a compression fitting and then screw a hose barb into that. Presumably cutting the adapter's barb off to allow the ferule on there?

I think I like Option 2 better as I fear the hose would slip off the adapter. But, you've reminded me that I have the stainless tubing that I'm not going to use, and it looks like the left end of that adapter. So for that size, which I think is 3/8", I could just use it and slip a compression fitting on.

I've also seen a male disconnect/6AN fitting, and I could use that with a 6AN/hose barb fitting. That would get me down to two pieces instead of three.

Anyway, thanks! At least I have some options.

[85lebaront2]

Bruce - I think I understand, but let me make sure.

Option 1 is to use the fuel line adapter shown below and slip a hose over it, placing a clamp in the recess?

Option 2 is to use that adapter with a compression fitting and then screw a hose barb into that. Presumably cutting the adapter's barb off to allow the ferule on there?

I think I like Option 2 better as I fear the hose would slip off the adapter. But, you've reminded me that I have the stainless tubing that I'm not going to use, and it looks like the left end of that adapter. So for that size, which I think is 3/8", I could just use it and slip a compression fitting on.

I've also seen a male disconnect/6AN fitting, and I could use that with a 6AN/hose barb fitting. That would get me down to two pieces instead of three.

Anyway, thanks! At least I have some options.

Gary, I actually ran Darth on EFI that way until I was sent the 1994 lines, it worked well with no leaks.