OBS Resurrection Fuel System (Part 5)

OBS Resurrection Fuel System (Part 5)

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Restoring an OBS truck can sometimes seam like a daunting task, but upgrading for more horsepower is always an exciting step in the build process. This truck has already seen some interior and exterior upgrades along with steering changes and even an RSK front suspension kit. When these 7.3L Power Strokes were new, they were non-intercooled and could put down around 180-200hp. This particular truck is planned to go much past that, with the goal of 450-horsepower. With 205cc injectors planned and a turbo to match it, a 1994-1997 7.3L could produce a dyno number to compete with a new Power Stroke, but it couldn’t sustain it for long. EGT’s would be through the roof with no intercooler and the factory mechanical fuel pump will never keep up.  A couple quick data logs of wide open throttle runs proved that in a hurry. Fuel pressure was dropping from 55-psi to the low 20’s and 1700-degrees on pyrometer is not good news and we still have a lot of fuel to add.


So, first things first, the fuel pressure problems. The 1994-1997 model years used a mechanical fuel pump located down in the valley of the motor. This pump is actuated by a small rod that rides on a lobe of the camshaft. While it’s simple technology and works, when it comes to moving the kind of volume bigger injectors need, it won’t move enough. The factory pump is extremely common for premature failure and leaks as well, so replacing it with a better performing and more reliable electric fuel pump can kill two birds with one stone. While we’re looking at increasing overall flow, there are quite a few other places in the factory fuel system that will need attention. For this truck, we opted to replace the entire fuel system from tank to heads to ensure we’d have enough flow and pressure to keep the engine happy for a long time.


Strictly Diesel of Phoenix, AZ has been doing performance 7.3L and 6.0L fuel systems for twenty years and their Driven Diesel fuel kits for the 1994-1997 Power Stroke come in many variations depending on each truck’s requirements and the owner’s preference. With hopes of making 450hp, they suggested their dual Bosch electric pump kit, fuel bowl delete regulated return, high flow banjo bolts and 5/8” pick-up tube.


The beauty behind this kit is the use of factory 99-03 7.3L Super Duty Bosch fuel pumps, so you maintain OE reliability with excellent performance to go with it. The factory Bosch has proven its ability to run 100,000+ miles without fail, so running two pumps in parallel can double fuel volume without giving up reliability. As an added bonus to the dual pump kit in this truck, is under daily driving and towing demands, if by chance one pump were to fail, the other pump can continue to supply fuel to the engine. The entire pump and filter assembly mounts to supplied stainless steel brackets you’ll locate to the inside driver’s frame rail where it’s tucked up safely out of the way from road debris.


These trucks were equipped with dual tanks, but the factory selector valve will be a major restriction in the system, so it will be bypassed with a high flow 5/8” draw straw in our front tank. This means we lose the use of our rear tank all together unless we built a transfer pump system to get fuel from the rear tank to the front tank or install a 38-gall tank from a Bronco.


Up on the engine we need to remove the factory fuel filter bowl (also prone to leaks), mechanical fuel pump and all associated fuel lines. The Driven Diesel Regulated Return kit includes larger fuel lines for improved fuel flow to the injectors and a high quality fuel pressure regulator to effectively manage fuel system pressure under the demands of high horsepower and towing. Eliminating the fuel bowl also cleans up the engine bay a bit and can make other repairs easier. Converting over to an electric fuel system with regulated return can have multiple benefits on an OBS Ford like quicker starts and a smoother idle. This complete tank to engine fuel system install can be rather labor intensive, but we’d dare say it’s a necessary upgrade on any 1994-1997 truck looking to support anything over factory injectors.


We can tell you, with our fuel pressure holding strong at the pre-set 65-psi the truck runs exceptionally well. Its nice having the peace of mind  that the new injectors will be happier getting the fuel volume at the required pressure when the time comes.


01 – When it comes to making power in the older 94-97 7.3L, the fuel system will be your biggest hold back. The factory mechanical pump can only move so much fuel, and with so many restrictions in the fuel system, maintaining proper fuel pressure is key to supporting 400+ horsepower. An electric fuel system conversion like the dual pump kit from Driven Diesel is an excellent option.



02 – The heart of Driven Diesels electric fuel conversion kit is the pumps and bracketry to mount it all. With a couple different options available depending on your power goals, Driven has multiple pump options. With plans of 450+ horsepower and lots of miles daily driving and towing, this dual stock pump kit seemed most logical. This system uses two factory Super Duty Bosch pumps, making it great for longevity, performance, and easy maintenance.



03 – Under the hood, not only is the mechanical fuel pump (buried down in the valley) not enough to support our 205cc injectors, they are prone to leaking and premature failure. The factory fuel bowl is also known for leaking so eliminating all of it from the system will resolve all those issues.



04 – With the fuel bowl removed, you have your first good look at the factory mechanical fuel pump. This pump operates off a piston that rides on a lobe of the camshaft, so once removed, the hole in the top of the engine block must be plugged off.



05 – The electric fuel system conversion will eliminate all restrictions within the factory fuel system including the factory fuel lines feeding the heads, the factory brass fittings, banjo bolts, and return lines. It also upgrades the fuel supply lines from the tank.


06 – The fuel pump and fuel filter bowl are out never to find their way back under the hood. It’s worth mentioning here, if your factory fuel bowl is still in good condition, they can bring a fair price on the classified market, so don’t just toss it in the garbage.



07 – Be prepared for this. Removal of the factory pump may not go as easy as you’d think, getting the plunger to pull up and out of the block can be a challenge. If you’re lucky it will wiggle right out, but if you’re like us, it’ll snap off, leaving you hopeing it doesn’t fall into the oil pan.



08 – With the use of a small magnet we pulled the center steel plunger up enough we could grab it with vice grips and wiggle it the rest of the way out. Easy peasy. No need to sweat it.



09 – Another upgrade worth looking into since you’re torn this far into the fuel system is upgraded fuel banjo bolts. These are found at the front and rear ports of the cylinder heads. You can see how much larger the fuel ports are within the banjos from Driven Diesel.



10 – The banjos are simple to replace once the accessory brackets are removed from the front of the engine. Just make sure these get torqued properly to place the right squish on the supplied copper sealing washer and ensure they won’t back out and leak.



11 – With the banjo bolts replaced it was time to move on to the installation of the fuel bowl delete and regulated fuel return parts on the engine. The new system uses all new fuel lines and fittings from tank to heads, improving fuel flow everywhere within the system. This combination of parts could supply fuel for over 600-horsepower.



12 – The new fuel distribution fuel block included in the regulated return system is now where fuel supply from the tank will be fed and distributed to the cylinder heads. This block makes plumbing fuel lines super simple and eliminates the need for the fuel filter bowl in the valley. Of course, fuel filtration is required, which is taken care of on the electric fuel pump brackets down along the frame.



13 – The new electric fuel conversion and filtration kit assembled easy and mounts right up on the frame directly behind the transfer case. The bracket allows installation of the dual Bosch pumps and a pre and post pump filter. The supplied Baldwin filters will not only help any water from the fuel but filter out any debris and particles within the fuel better than the factory filter can.



14 – To properly feed the new dual fuel pumps, the tank was dropped for the installation of Driven Diesels 5/8” pick-up tube kit. The new pickup eliminates restrictions  before the pumps. This does mean we’ll be eliminating our tank selector switch, so we no longer have use of the second fuel tank. If you need both tanks, or big fuel capacity there are plenty of options, like a 48-gallong Bronco tank, or a transfer pump to move fuel from one to the other.



15 – To make the return to tank plumbing as easy as possible, Driven Diesel supplies this super trick billet adapter fitting that allows you to attach the new -AN fuel return line to the factory quick connect hard line on the frame behind the driver front tire. This allows fuel to return right back to the tank in the factory fuel line, with no concerns about leaks.



16 – With the complete fuel system installed can see just how neat and tidy the engine bay is now. Gutting that mechanical fuel pump and fuel bowl leaves so much space to work around the valley of the engine. And the new fuel distribution block and regulator on the fuel return side look nice all plumbed.