question for the EFI guys
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Elder User
Joined: Oct 2016
Posts: 712
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From: Mesa, AZ
question for the EFI guys
My truck has dual tanks, including an in cab tank, with the OEM tank switch.
EFI requires a lot more fuel pressure, so if anyone has swapped over to one of the EFI kits, how did you plumb fuel pumps and lines, and does the factory tank switch hold up to the higher pressures?
What about Return lines? how would that work on tanks that don't have those today?
Lastly, are vented caps needed? My rear tank will spew fuel on a hot day if I use a vented cap.
Just getting ideas now and thinking of some of the pitfalls.
EFI requires a lot more fuel pressure, so if anyone has swapped over to one of the EFI kits, how did you plumb fuel pumps and lines, and does the factory tank switch hold up to the higher pressures?
What about Return lines? how would that work on tanks that don't have those today?
Lastly, are vented caps needed? My rear tank will spew fuel on a hot day if I use a vented cap.
Just getting ideas now and thinking of some of the pitfalls.
Mountain Pass
Joined: Feb 2003
Posts: 229
Likes: 4
On my F250 with EFI I just have one tank. I mounted the pump on the framerail back near the tank and hooked to the factory pickup/sending unit. For a return, I bent up a small piece of 3/8 steel brake line, drilled a hole in the metal section of the filler neck, welded the brake line into the neck (off the truck, of course), and hooked return line to it. So returned fuel just runs back into tank. I’m pretty sure it’s a factory vented cap. Sorry, no experience with dual fuel tanks.
Cargo Master
Joined: Apr 2010
Posts: 2,600
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From: Billings, MT
I would put a 38 gallon tank in the back and just run one. Best way to make dual tanks work would be to go to a '92-'96 setup with check valves and such but it will be a big hassle. Bronco graveyard 38 gallon tank and Tanks Inc. In tank setup is what I would do and plan to on my supercab
Fleet Owner
Joined: Dec 2009
Posts: 20,678
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From: NorCal
I'm running the Edelbrock E-Street EFI Version 1 in my 2WD '70 longbed..... currently returnless and supplied by the in-cab tank. The ECU pulses the electric fuel pump to achieve the correct pressure. It'll be converted to a return system once I swap in a rear-mounted fuel tank.
An alternative is to install a fuel sump where there is an internal high pressure electric pump to provide the required 45-60 PSI. The sump reservoir is supplied by the OE mechanical pump.
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An alternative is to install a fuel sump where there is an internal high pressure electric pump to provide the required 45-60 PSI. The sump reservoir is supplied by the OE mechanical pump.
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Elder User
Joined: Oct 2016
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From: Mesa, AZ
I would put a 38 gallon tank in the back and just run one. Best way to make dual tanks work would be to go to a '92-'96 setup with check valves and such but it will be a big hassle. Bronco graveyard 38 gallon tank and Tanks Inc. In tank setup is what I would do and plan to on my supercab
That's a lot of weight behind the axle on a soft sprung half ton that already has a 100lb bumper with a 100lb spare tire hanging on it.
Lead Driver
Joined: Jul 2017
Posts: 9,600
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From: San Jose, CA
Even if the stock valve would handle the pressure (and it might I suppose) I would still swap it out for a modern motorized electric valve with six ports. It adds to the cost of the EFI swap, but simplifies things greatly, with the ability to route the return fuel to the tank that's being used.
This typically means dual fuel pumps if using in-tank pumps, but can be used as a single-pump distribution center if you plumb the pump after the valve.
The trick comes in mounting the valve as far back as possible so that the pump can remain nearer the rear of the truck than the front. Electric pumps prefer to push, rather than pull.
Many of the Bronco guys with dual tanks opt to run a single engine-feed pump with no switch valve. They simply use the main tank for the engine, then use the secondary/aux tank as a transfer tank. A second, low-pressure (cheap) pump on a switch just pumps the fuel out of the aux tank into the main when it runs low.
Been working like that for many years. So the options are still many, you just have to think them through and see which one looks the best for your truck.
Paul
This typically means dual fuel pumps if using in-tank pumps, but can be used as a single-pump distribution center if you plumb the pump after the valve.
The trick comes in mounting the valve as far back as possible so that the pump can remain nearer the rear of the truck than the front. Electric pumps prefer to push, rather than pull.
Many of the Bronco guys with dual tanks opt to run a single engine-feed pump with no switch valve. They simply use the main tank for the engine, then use the secondary/aux tank as a transfer tank. A second, low-pressure (cheap) pump on a switch just pumps the fuel out of the aux tank into the main when it runs low.
Been working like that for many years. So the options are still many, you just have to think them through and see which one looks the best for your truck.
Paul
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Tend to leak coolant at the passenger side crossover. It ends up taking a new intake manifold. I just got done replacing mine myself with help from this forum and YouTube. Big job, but got it done. Seems like it is just a matter of time before this happens according to others on this forum.
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Cargo Master
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As far as return lines, a common trick is to just add a new supply line, and use the old/existing supply line as the return.
I would (and hopefully will) try to grab the stuff from an '87 or newer F-series, and put an OEM EEC4 or even OBD2 4.9 EFI in my rig.
From what I know, the fuel cap will depend upon what engine control computer you use. OBD1 EEC4 would most likely not notice what cap is on your filler, but I think the OBD2 stuff does somehow monitor tank pressure - I guess through the evap system. Either way, you will need to run the evaporative emission system to keep the computer from logging error codes.
If you're using an aftermarket computer, I suspect that most of those don't offer any provisions for emission controls.
I think modern vehicles with returnless systems micromanage the fuel pump in order to hit pressure targets. With the old OBD1 stuff, it's either on, or it's malfunctioning...
I would (and hopefully will) try to grab the stuff from an '87 or newer F-series, and put an OEM EEC4 or even OBD2 4.9 EFI in my rig.
From what I know, the fuel cap will depend upon what engine control computer you use. OBD1 EEC4 would most likely not notice what cap is on your filler, but I think the OBD2 stuff does somehow monitor tank pressure - I guess through the evap system. Either way, you will need to run the evaporative emission system to keep the computer from logging error codes.
If you're using an aftermarket computer, I suspect that most of those don't offer any provisions for emission controls.
I think modern vehicles with returnless systems micromanage the fuel pump in order to hit pressure targets. With the old OBD1 stuff, it's either on, or it's malfunctioning...
Fleet Mechanic
Joined: Aug 2005
Posts: 1,462
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From: Hartford, AL
i use Fitech EFI with Fitech fuel command center. Stock pump feeds fuel normal to fuel command center at carb pressures, the 1 quart sump has a 60 psi pump submersed and feeds the Fitech. Excellent system and very happy with throttle response, performance, cold weather starts and just general drivability of EFI. Another benefit is cpu in enclosed in throttle body so no computer to mount elsewhere. For this setup you do need a vent line return to fuel tank and yes you need a vented cap. I just drilled a small hole in the disc on my cap. One caveat is I did modify the sump and removed the float and made my vent line the return line. I just plumbed it into the filler neck. You can get the entire system for about a grand.
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