Efi fuel requirements for early Bronco

Bought an early Bronco (72) for the wife as a project and very happy to have it on the road.  

The joys of a carb and old manual transmission are not lost on me. My wife, however.....    let's just say that I am beyond happy that she agreed to a project vehicle and I want her to enjoy it as much as possible.  

So to that end I am looking for an auto tranny (c4, maybe c6) and the linkages and whatnot I'd need to run it. 

But this thread is about the fuel system.  I am looking at a Holley sniper or fitech tbi kit.  I need more fuel and fuel pressure for them and was considering the fuel system that they sell. Fitech, at least, sells a fuel command center that mounts under the hood and uses stock tanks, lines and pump.  You add a vent back to the tank. No prob. 

But I was wondering if anyone could advise on an idea I had after reading mikeydriftsjunk's post about corvette c5 fuel filters having a regulator and a return outlet built-in.  

Noting that the bronco has two tanks that come together at a manual valve, could I mount an external high pressure pump after the valve that feeds the c5 filter and run the return to main tank?? And run the outlet of the filter to the engine???

Generally, electric fuel pumps are happier pushing fuel vice pulling it. Coming from two tanks, I’d be concerned about burning up pumps. Can you run a single tank in between the rear frame rails a la K5 Blazer? It would simplify everything, and you could run an in-tank pump.

Generally i have heard absolute horror stories about the fitech fuel command center and very good things of their actual system.

check to see if tanks inc makes an efi tank that bolts in, they do for lots of popular classics.  

I chose the Holley sniper with a tanks inc. new fuel tank with internal electric pump.  I heard mixed reviews on the fitech kit,  and lots of bad feedback on their fuel command center.  Then I called their sales/support line to get some more details on the various kits and just didn’t get a good vibe from the support team.  I’ve ran other Holley fuel injection systems in the past and always had good luck with their support,  so in the end that’s the direction I felt most comfortable with.  It isn’t  installed yet,  but I hope to have it in sometime next month.

Cheap high flow external pump.

Last external i installed (that wasn't used or converted from an internal..long story) was a lower-rated one of these. Then i found the higher rated one above. D'oh! 

Anyway, i'd just install it after your switching valve and just make sure it's mounted lowish on the frame. As far as your regulator/filter, i would actually just tee that back into the inlet side. Your supply line would also be your 'return' line. This sounds funny but people used to actually do this when they would install 'booster pumps' to up the pressure of systems with in-tank pumps that had regulators built in. They would just hook the return back to the inlet side! 

I wouldn't worry too much about using the electric pump to suck fuel out of the tanks and through the lines. It may hinder its output minorly compared to sucking straight from a submerged pump-mounted strainer, but i can guarantee it wouldn't be of consequence to a stockish 70s engine where the pump above would have miles of excess capacity. As long as the point that the fuel comes out of the tank is higher than the inlet to the fuel pump, gravity dictates there will always be liquid fuel at the inlet of the fuel pump (similar concept to the S-shaped pipe under a sink or in a toilet). Even if the fuel wanted go drain away from the pump inlet, the pump outlet has a spring-loaded check valve that will prevent it just like putting your thumb over a straw and picking it up out of a drink. If nothing is allowed in to displace it, nothing will flow backwards from the pump inlet. 

Don't tee the return to the pump inlet, that's a bad idea for a lot of reasons.

If you do have a switching valve, EFI is going to be tricky exactly because of the fuel return.  Probably the best course of action would be the mechanical pump on the engine feeding a small secondary tank (what one of those fuel conversion boxes is). 

EFI vehicles with dual tanks actually switch the return line and which pump is feeding.  EFI pumps have check valves in them, so you don't need to switch the feed line, just which pump is energized.

Megasquirt and Mustang or F150 parts not of interest once you have the pump and return set up?

I used the FiTech kit on my '69 Cougar.  The Holley was not yet available.  I bought a new FI fuel tank with internal pump as the Fuel Command Center from FiTech appeared to have some issues and I didn't want to have the reservoir in the engine bay.  On your dual tank set-up, it may make the most sense if they've gotten the problems squared away.   Your existing mechanical pump suck fuel from whatever tank you select with the valve and supplies it to the FCC.  The in-sump pump in the FCC then builds pressure and flow for the fuel injection system.

I'm curious about these systems now that the prices are in the range of less than $1000. Looking forward to further discussion. 

For a fuel system, keeping it simple and doing it right is best.  The problem with the C5 filter/regulator is that it works for the C5 but might not work well with anything else.  The best way to get steady, predictable pressure is to keep the regulator as close to the injectors as possible.  The corvette regulator is simple packaging, but they designed it to provide X psi based on the C5 fuel lines, distance, diameter, etc.  You can probably get close enough with your system to use the C5 regulator, but in some cases it doesn't work and then you've spent money on something you can't use.

I might suggest calling Inline Tube or Classic Tube.  You can order pre-bent lines, and there is a good chance that a 72 Bronco had an optional return line on CA cars.  Even if they didn't you could order an extra supply line and run it right beside the supply.  That is a super-simple way to get all the plumbing you need to the engine bay.  Then you can get an inexpensive regulator for the firewall and choose whatever pump you want.

It is true that pumps like to push and not pull, but since liquids are not compressable (or expandable) it usually doesn't make much difference once you get fuel to the pump.  The only time I've had trouble with an external pump is when I mounted it too high, and even then it only was a problem if I ran the tank dry.  It wasn't good at moving vapor so it had a tough time overcoming gravity and sucking fuel up to it.

My main concern is not how to return the fuel; its where to return the fuel.  You could plumb the return into one tank but that has two frustrating side effects.  Let's say you return it to the front tank.  With both tanks full, if you pull from the rear tank, surplus fuel bypasses the regulator and gets pumped into the front tank while none is being removed.  I suppose there is a potential for overflow.  Also, if both tanks are low and you're working on your last gallon from the rear tank it's going to pump surplus to the front tank and you might have to "chase the fuel."

Is there a way to connect the tanks?  Just basically make it one big one instead of two little ones?  I never really looked in an early bronco.  I know some of the pickups had aftermarket single tanks that replaced the rear tank with a larger single.  Overall capacity was lower, but it bypassed all the switches and valves.

This brings me to a very difficult thing to say... What about a deadhead regulator with no return?  I never recommend those since its too easy to mismatch components and either go too small with supply and starve for fuel, or go too big with supply and it overheats the fuel and/or overcomes the regulator and floods.  Might be worth looking into though.

Yeah, I've got no experience with these vehicles *at all*, so grain of salt; could you basically have one drain into the other at all times using tubing?  No valve, just a tank running into a second tank, second tank runs to an inline pump, return line runs into the top of the tank closest / easiest to reach from the engine?  I thought there were some Ford trucks or vans that had a frame mounted pump that would be easy to use for the pressure side.  

Having done close to 30 EFI conversions from carbureted I have a lot of information to get. Will do so when place where I can get my thoughts together and put them down for you

Adding a return to an existing fuel tank is not particularly difficult if there's only one  - the current version of my Dart has a sump (made from a Wal-Mart bread pan!) welded to the tank for a pick up, with the return run in through the original sending unit pick up, but there are plenty of other ways using bulkhead fittings. The dual tanks mainly add one twist - you'd need to switch the return at the same time you switch feeds.

Look here   https://bcbroncos.com/

Is this a V8 or I6 powered?  If V8, grab the intake and EFI parts from a later EFI equipped engine.  Factory or aftermarket ECU (MegaSquirt is my preference, but to each their own).  No need to deal with TBI and it limitations.

If its an I6, that's a little more tricky, but a GM TBI unit from a big block engine would be a less expensive and easy to repair solution.  Control it with MegaSquirt and done.

For the fuel system, that is tricky.  Not impossible, but tricky.  I would actually make it a bit more simple though:  Put a surge/swirl tank in the engine bay, use stock fuel pump to fill tank, mount the EFI pump in the tank, plumb high pressure fuel to the EFI solution desired, return excess to swirl tank.  Leave stock fuel system alone (aside from new fuel lines and cleaning the tanks).

In reply to Stefan

If its an I6, that's a little more tricky, but a GM TBI unit from a big block engine would be a less expensive and easy to repair solution.  Control it with MegaSquirt and done.

IIRC the last few years of the F150 w/300/I6 were FI from the factory.

mike said:

 

In reply to Stefan

If its an I6, that's a little more tricky, but a GM TBI unit from a big block engine would be a less expensive and easy to repair solution.  Control it with MegaSquirt and done.

 

IIRC the last few years of the F150 w/300/I6 were FI from the factory.

Nice.  That would be a better solution, or at least a less expensive and easier to fabricate solution.

Why the suggestion of a TBI unit from a big block?  5.0 or 5.7 two barrel units from GM are not all that large from a CFM standpoint.  They're pretty common as well vs. the big block units.

The small block TBI's don't flow as well and the injectors sit in the way, so the flow is always restricted with either setup. 

If you're going to use a TBI (gag), might as well use one that will more than meet your needs, especially as you have control over the fuel via the EFI computer, so you can dial the fuel back a bit.

Great ideas.  It is a v8 (351w) and this is just an around town soccer mom mobile, so I'm not looking for hp, just ease of use. 

I will look into a Ford efi set up - do the 5.0 intakes bolt onto these 351w's?

any rough idea on cost to put it together??

For an around town job, use the swirl pot/surge tank discussed earlier.  E2000 pump will be plenty and cheap.

5.0 won't fit 351w. However, plenty of 351w injection engines exist.

Personally, id grab either the holley or msd self learning kits, drop it on the 4bbl manifold, and forget about it. 

In reply to Dusterbd13 :

Can you elaborate on the e2000 pump and a good way to make/buy the pot??

Surge tank almost exactly like what i use

E2000 pump

Pump is rail mounted downstream from outlet of the surge tank.

Helpful?

Don't tee the return to the pump inlet, that's a bad idea for a lot of reasons.

Elaborate?   

I would never do this if i were building a fuel system from the ground up, but in the 90s this was done when supercharging/turbocharging vehicles that ended up with probably 3-4 times the power of a 70-something stock 351. About the only issue i see with it is if you care about fuel heating, then yes your fuel will be hot from recirculating through the pump a lot. Then again, if you're getting pinging/detonation on a 7:1 CR stock 1970s motor, you probably have other problems. So.. what's the hangup?