Edelbrock Pro Flo (Actual user and installer feedback)

[Rusty_S85]

The Pro Flo 4 was always highly rated when I was looking. If you dont mind spending the extra money to make more changes such as throttle cable and C4/C6 kick down then I say go for it. I didnt want the extra headache of doing custom throttle and kick down so I went the way I did.

[Pete Whitstone]

Also, people complain about the lack of suitable mount for it so be prepared to fabricate something.

Lastly, and this still seems to be up for debate, the sump pump unit does have a return. They advertise it as not requiring modifications to your fuel system, but I’m not familiar with any mechanical fuel pump that has a return. So in theory, if you follow the directions, you still need to run a new return line to the tank. What happens if you don’t? Not sure…

100% agree on the first paragraph, something will have to be fabricated to mount this thing. And it is pretty big, but I think it's about as compact as it could be, given the parts inside.

I don't understand your logic on needing to run a return line to the tank. In a stock carb situation, the mechanical pump deadheads against the closed float needle, so no return necessary. In this situation, the mechanical pump deadheads against the closed float needle in the Edelbrock part, so why is a return now necessary?

The instructions are very clear about having to run a vent line to the tank (or T into an existing vent line), but that is not to return fuel.

In my case, I bought the sump before I started another project, to convert to a serpentine belt system. I did not think it all the way through, but the later timing cover did not have a mechanical pump boss. So I had to add a small electric pump to replace the mechanical pump. So at this point, does it make sense going forward with a small electrical pump to drive the big electrical pump, or should I just ditch the sump unit and go completely to an in-tank pump like the later trucks had? In the end I think that would be more work because then we are getting into my non-stock sending unit, probably have to replace the tank with a later one, and so on. The path of least resistance is probably to go forward with the sump I guess.

[Rusty_S85]

Also, people complain about the lack of suitable mount for it so be prepared to fabricate something.

Lastly, and this still seems to be up for debate, the sump pump unit does have a return. They advertise it as not requiring modifications to your fuel system, but I’m not familiar with any mechanical fuel pump that has a return. So in theory, if you follow the directions, you still need to run a new return line to the tank. What happens if you don’t? Not sure…

100% agree on the first paragraph, something will have to be fabricated to mount this thing. And it is pretty big, but I think it's about as compact as it could be, given the parts inside.

I don't understand your logic on needing to run a return line to the tank. In a stock carb situation, the mechanical pump deadheads against the closed float needle, so no return necessary. In this situation, the mechanical pump deadheads against the closed float needle in the Edelbrock part, so why is a return now necessary?

The instructions are very clear about having to run a vent line to the tank (or T into an existing vent line), but that is not to return fuel.

In my case, I bought the sump before I started another project, to convert to a serpentine belt system. I did not think it all the way through, but the later timing cover did not have a mechanical pump boss. So I had to add a small electric pump to replace the mechanical pump. So at this point, does it make sense going forward with a small electrical pump to drive the big electrical pump, or should I just ditch the sump unit and go completely to an in-tank pump like the later trucks had? In the end I think that would be more work because then we are getting into my non-stock sending unit, probably have to replace the tank with a later one, and so on. The path of least resistance is probably to go forward with the sump I guess.

Vapor lock is why, those canisters without a return has had issues with the low pressure fuel circuit vapor locking causing the EFI to run horribly. That is how the FiTech fuel pump module used to be without a return but now they all have a return cause without the return it caused issues.

[Pete Whitstone]

Vapor lock is why, those canisters without a return has had issues with the low pressure fuel circuit vapor locking causing the EFI to run horribly. That is how the FiTech fuel pump module used to be without a return but now they all have a return cause without the return it caused issues.

Interesting, I have not heard anything about this. Vapor lock is basically the gas boiling in the fuel line or the float bowl, right?

So what induces the heat? The placement of the fuel line near the hot engine parts, or the deadheading against the floats? I have to believe the former is a far greater factor than the latter, and the problem can be avoided with good insulation and component placement.

I sure hope so, anyway... there is no provision on the one I have for any type of return on the low pressure side.

[Littlebeefy]

Vapor lock is why, those canisters without a return has had issues with the low pressure fuel circuit vapor locking causing the EFI to run horribly. That is how the FiTech fuel pump module used to be without a return but now they all have a return cause without the return it caused issues.

Interesting, I have not heard anything about this. Vapor lock is basically the gas boiling in the fuel line or the float bowl, right?

So what induces the heat? The placement of the fuel line near the hot engine parts, or the deadheading against the floats? I have to believe the former is a far greater factor than the latter, and the problem can be avoided with good insulation and component placement.

I sure hope so, anyway... there is no provision on the one I have for any type of return on the low pressure side.

This is exactly why I said the return line requirement for the sump is up for debate. It’s true it’s not a “Return” line in the way that it would be on an OEM EFI, but the manufacturer clearly states that fuel (in some form) needs a path of to return to the tank. There are lots of opinions on the necessity, function and proper installation of the line on all the websites. In the end, I just went with an intank pump so I have no insight myself.

Whichever way you go you will likely need to engineer something specific for you. Whether it’s a mount for the sump, a bracket for the throttle, a modification to the hanger, etc. fuel seems to be the most DIY aspect of the Pro Flo.

For those of you intrepid mechanics who are considering the EFI conversion and are also worried about addressing fuel, a very popular and simple way of going about it is “fuel pump on a stick”. Essentially, you take a stock style hanger and affix a HP pump at the proper length to reach the bottom of the tank. Then you can add an inlet to the hanger and put it in a stock fuel tank. Can’t always be done and isn’t always simple but if the tank opening is wide enough to fit the pump through, the rest is mostly just hoses and clamps.

[Rusty_S85]

Vapor lock is why, those canisters without a return has had issues with the low pressure fuel circuit vapor locking causing the EFI to run horribly. That is how the FiTech fuel pump module used to be without a return but now they all have a return cause without the return it caused issues.

Interesting, I have not heard anything about this. Vapor lock is basically the gas boiling in the fuel line or the float bowl, right?

So what induces the heat? The placement of the fuel line near the hot engine parts, or the deadheading against the floats? I have to believe the former is a far greater factor than the latter, and the problem can be avoided with good insulation and component placement.

I sure hope so, anyway... there is no provision on the one I have for any type of return on the low pressure side.

On that system with the fuel pump module the way it works is as follows.

Mechanical fuel pump pumps fuel into the fuel pump module

Electric high pressure pump in fuel pump module feeds Fuel Injectors

The high pressure electric pump is sitting in the fuel and is cooled by the fuel. This cooling effect of the fuel on the pump is introducing heat to the fuel itself and because there is no pressure in the fuel pump module to raise the boiling point it will boil more easily and turn into a vapor than the 5 to 6 psi pressure in the mechanical fuel pressure line.

The return is to ensure the fuel in the module that has been heated up not just by the mechanical pump but by cooling the electric fuel pump as well is put back into the fuel tank to cool while fresh cooler fuel is brought in.

Its why we put the electric fuel pumps in the tank now cause the fuel cools the pump makes them not just run quieter but run cooler and last longer. Now we used to have return lines at the motor but now many late model cars are going for the returnless design where the fuel pump module in the fuel tank returns directly in the tank with only a single feed line. Many claim you cant do that because the fuel will boil but fuel pressurized at 60 psi would require your engine to over heat and seize up to generate enough heat to boil fuel at those pressures.

Now on the question of its debatable on the return for the command module assembly its not debatable, if it was they wouldnt have redesigned every one of them to have a return port when before they did not have a return port but a single in and out hook up.

[Pete Whitstone]

Now on the question of its debatable on the return for the command module assembly its not debatable, if it was they wouldnt have redesigned every one of them to have a return port when before they did not have a return port but a single in and out hook up.

OK, that's where I am getting tripped up. The Edelbrock documentation never refers to the return port as a gas return line. They refer to it as a "fuel sump vent line". Implying that it would carry vapors, not actual gasoline. The documentation reinforces that idea by stating "If the vehicle has a vent line, you can tee into this line".

It seems to me that if the "fuel sump vent line" is carrying liquid gasoline, and you tee it into the vent line, it's going to flow not only to the tank, but to the charcoal canister. Unless there's a check valve in the stock Ford system somewhere that I'm not aware of. If there is, it had better be close to the canister, because they don't specify WHERE in the vent line you should tee into.

They do stress that it has to be routed back to the tank, and not into open air, or pointed towards the ground, or routed to the intake manifold. All of which seems like it would work (not optimally, but would work) if the line was only carrying vapor.

The documentation seems contradictory and confusing, at this point.

 

[Rusty_S85]

Now on the question of its debatable on the return for the command module assembly its not debatable, if it was they wouldnt have redesigned every one of them to have a return port when before they did not have a return port but a single in and out hook up.

OK, that's where I am getting tripped up. The Edelbrock documentation never refers to the return port as a gas return line. They refer to it as a "fuel sump vent line". Implying that it would carry vapors, not actual gasoline. The documentation reinforces that idea by stating "If the vehicle has a vent line, you can tee into this line".

It seems to me that if the "fuel sump vent line" is carrying liquid gasoline, and you tee it into the vent line, it's going to flow not only to the tank, but to the charcoal canister. Unless there's a check valve in the stock Ford system somewhere that I'm not aware of. If there is, it had better be close to the canister, because they don't specify WHERE in the vent line you should tee into.

They do stress that it has to be routed back to the tank, and not into open air, or pointed towards the ground, or routed to the intake manifold. All of which seems like it would work (not optimally, but would work) if the line was only carrying vapor.

The documentation seems contradictory and confusing, at this point.

Hmmm sounds like they are doing different than the command module that is used with the FiTechs, those are actual returns if you take the top off it has no check valve to prevent liquid flow it is a straight up open hole that has to go back to the tank as on that setup the pump regulates pressure and dumps fuel back into the command module with the mechanical pump still pumping fuel into it with the return line sending excess back to the tank to cool.

If Edelbrock is using it as a vapor line to vent the canister of vapors and it has an actual check valve to prevent fluid to pass through then what they are doing is similiar to the Command modules used with FiTechs its just they are allowing the fuel to expand into a vapor and vent out to prevent vapor lock where as the other is trying to prevent the fuel from even turning into a vapor by keeping the fuel cool by constantly cycling it.

Sounds like two different techniques to tackle the same problem. Im not familiar personally with the Edelbrock command module and assumed it was the same function as the ones I have had personally messed with before and have taken apart. Either way I would personally put the so called vent line to the fuel tank itself cause the fuel tank is vented to the charcoal canister, you could vent it to the vent line with a Tee by the tank, after all the vent valve in the top of the fuel tank has a check valve that closes in the case of a roll over to prevent fuel from just pouring out of the tank.

[Nickelplate]

I have been installing mine over the course of a few days. My truck is a 1986 Bronco with the EFI 5.0L. The fact that there was an existing fuel injection system presented some challenges. I'm going to write my experience so far for anyone else doing a similar swap.

Oil Pressure (for truck with gauges) - You can run a wire from your sending unit to the White/Red wire in connector C-325 (on the drivers-side fender apron).

Water Temp (for trucks with gauges) - You can run a wire from the stock sending unit to the Red/White wire in connector C-325. The Edelbrock comes with two NPT-threaded holes right next to the thermostat housing. The larger one is for your heater hose neck. The other one fits the stock Ford water temp sending unit perfectly.

Tach Signal - The bullnose trucks have that weird pulsed tach signal that won't work with more modern ECUs. Rocketman can convert your old tach to work with the 12v square wave signal that the Edelbrock system sends. You can find Rocketman's page here: https://www.rccinnovations.com/index.php?show=menu-tach-all . To avoid having to hack into your wiring harness, or running a custom wire, I think you can take the tach signal wire from the Edelbrock to one of the wires that originally came off of the old ford TFI. Here is a diagram of the TFI wiring. The center two wires go to connector C-321 (another one on the Drivers-side fender apron). I am not sure which one to use yet, but I will come back and post again when I figure that out.

ECU location - I used the stock ECU location. I got a new grommet from here: https://lmr.com/item/LRS-14603/1979-93-Mustang-PCM-Harness-Firewall-Grommet for a good seal on the old firewall hole. Then I removed the old EEC and bracket and mounted the Edelbrock computer to the old bracket and put it back. I ended up welding threaded studs to the bracket so that the ECU would slide on and off more easily. Then I just tightened it down with some Nylock nuts. Here is a picture of the ECU in its final location.

Throttle and AOD kickdown linkages - The following kit comes with everything you need in order to use your stock AOD kickdown linkage, and an aftermarket throttle cable (I don't know which one I will use yet). https://www.edelbrock.com/throttle-and-trans-kickdown-for-4150-style-pro-flo-3-throttle-body-8041.html As for using cruise control, you should be able to shorten your stock cruise cable and use a Lokar cut-to-fit throttle cable end. https://www.speedwaymotors.com/Lokar-S-1034-Carb-End-Assembly-for-Lokar-Throttle-Cables-,96879.html And there is a "piggyback" for throttle and cruise control that Lokar makes. I cannot find the part number for that piece, but it is pictured in this article. https://autocentricmedia.com/news/lokar-introduces-throttle-and-kickdown-cable-mounting-brackets-for-edelbrock-pro-flo-4-efi/

Fuel system - The edelbrock system uses -6an connectors for the fuel system and does not use a fuel return line like the Bronco originally had. So in order to adapt the two and not have to make many changes to my fuel system, I opted to go for this regulator. https://www.summitracing.com/parts/edl-1728 . The stock front fuel pump on the Bronco uses the quick disconnect kind of end and a nylon fuel line. You can actually remove the quick disconnect end and get one of these 10mm to -6an adapters to screw into the front instead. https://www.polyperformance.com/wlb-128-3039-obi Then you can run all the supply lines as -6an. Use this part https://www.summitracing.com/parts/ICB-F060R312BA to adapt your stock Ford return line to the Edelbrock fuel pressure regulator, and that completes the fuel lines.

I have not hooked up the fuel pump wiring yet, but I will return with more info after I figure out the best way to get it all connected and wired neatly.

I will edit this port for any corrections if possible, and will post more in this thread as I find out more. Hope this was helpful!

[dsstephens]

I have been installing mine over the course of a few days. My truck is a 1986 Bronco with the EFI 5.0L. The fact that there was an existing fuel injection system presented some challenges. I'm going to write my experience so far for anyone else doing a similar swap.

Oil Pressure (for truck with gauges) - You can run a wire from your sending unit to the White/Red wire in connector C-325 (on the drivers-side fender apron).

Water Temp (for trucks with gauges) - You can run a wire from the stock sending unit to the Red/White wire in connector C-325. The Edelbrock comes with two NPT-threaded holes right next to the thermostat housing. The larger one is for your heater hose neck. The other one fits the stock Ford water temp sending unit perfectly.

Tach Signal - The bullnose trucks have that weird pulsed tach signal that won't work with more modern ECUs. Rocketman can convert your old tach to work with the 12v square wave signal that the Edelbrock system sends. You can find Rocketman's page here: https://www.rccinnovations.com/index.php?show=menu-tach-all . To avoid having to hack into your wiring harness, or running a custom wire, I think you can take the tach signal wire from the Edelbrock to one of the wires that originally came off of the old ford TFI. Here is a diagram of the TFI wiring. The center two wires go to connector C-321 (another one on the Drivers-side fender apron). I am not sure which one to use yet, but I will come back and post again when I figure that out.

ECU location - I used the stock ECU location. I got a new grommet from here: https://lmr.com/item/LRS-14603/1979-93-Mustang-PCM-Harness-Firewall-Grommet for a good seal on the old firewall hole. Then I removed the old EEC and bracket and mounted the Edelbrock computer to the old bracket and put it back. I ended up welding threaded studs to the bracket so that the ECU would slide on and off more easily. Then I just tightened it down with some Nylock nuts. Here is a picture of the ECU in its final location.

Throttle and AOD kickdown linkages - The following kit comes with everything you need in order to use your stock AOD kickdown linkage, and an aftermarket throttle cable (I don't know which one I will use yet). https://www.edelbrock.com/throttle-and-trans-kickdown-for-4150-style-pro-flo-3-throttle-body-8041.html As for using cruise control, you should be able to shorten your stock cruise cable and use a Lokar cut-to-fit throttle cable end. https://www.speedwaymotors.com/Lokar-S-1034-Carb-End-Assembly-for-Lokar-Throttle-Cables-,96879.html And there is a "piggyback" for throttle and cruise control that Lokar makes. I cannot find the part number for that piece, but it is pictured in this article. https://autocentricmedia.com/news/lokar-introduces-throttle-and-kickdown-cable-mounting-brackets-for-edelbrock-pro-flo-4-efi/

Fuel system - The edelbrock system uses -6an connectors for the fuel system and does not use a fuel return line like the Bronco originally had. So in order to adapt the two and not have to make many changes to my fuel system, I opted to go for this regulator. https://www.summitracing.com/parts/edl-1728 . The stock front fuel pump on the Bronco uses the quick disconnect kind of end and a nylon fuel line. You can actually remove the quick disconnect end and get one of these 10mm to -6an adapters to screw into the front instead. https://www.polyperformance.com/wlb-128-3039-obi Then you can run all the supply lines as -6an. Use this part https://www.summitracing.com/parts/ICB-F060R312BA to adapt your stock Ford return line to the Edelbrock fuel pressure regulator, and that completes the fuel lines.

I have not hooked up the fuel pump wiring yet, but I will return with more info after I figure out the best way to get it all connected and wired neatly.

I will edit this port for any corrections if possible, and will post more in this thread as I find out more. Hope this was helpful!

Thread revival...Long time lurker and infrequent poster here...mainly because our (project with my son) bronco has been laid up for years with a myriad of electrical problems and no priority to fix it. Fast forward to now, we've given up on getting the wiring and the original (but modified to fiveology racing sequential/maf style efi) stuff working and took the dive into the pro flo 4.

I *think* I've got everything (which means I do not) and we've started removing all the older - but still newer kit - like the edelbrock performer truck intake, bbk throttle body and a bucketload of problems that I'd sink in the middle of lake hartwell if it wasn't illegal.

No idea what many of the electrical thingamabobs are under the hood, but removing the old harness to the eec and the eec gave me great joy. I'm sure that will be short lived when I go trying to figure out why it won't start, but for now it feels like a win.

We've owned this truck for 6 years...and ran like a beast for 1 of them. It's ready to get moving again and this (and many other) threads on this system have inspired some confidence that this system was a good choice!

@nickelback any further insights on the return line for the fuel and the fuel pump wiring?