Part Ten: Fuel Supply

Project Obsessed has come quite a long ways since we picked it up last year and while we’ve tried to keep it looking as original as we could, that’s far from true when it comes to what’s under the hood. The whole idea behind this project was to take a 1994-1997 Ford F350 that so many of us have fond memories of from twenty years ago and turn it into something that could keep up with today’s late model trucks. Of course, we had to upgrade the suspension so it would ride better, and we had to beef up the steering, but obviously we really needed to focus on the performance side of things. When these 7.3L Power Strokes were new, they were non-intercooled and could put down around 180-200hp. With a 2020 Power Stroke capable of twice that in stock form, a 7.3L will need quite a bit of attention to make 400+ horsepower. Don’t worry though, it’s capable of doing it and this F350 is getting an excellent combination of parts to get it there.

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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 this duel pump kit from Strictly Diesel is your best option.
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The heart of Strictly Diesel’s electric fuel conversion kit is the pumps, and with a couple different options available you can find the setup perfect for your needs. With plans of 450+ horsepower and lots of miles daily driving and towing, we opted for the dual pump kit that uses two factory Super Duty Bosch pumps. This setup works great for both performance and longevity.

To start things off it received a Banks intercooler kit and Monster exhaust, along with S&B Filters cold air intake and custom tuning from A&A Design. With just those basic mods power was bumped up to 306hp at the wheels so then added some 205cc injectors from Full Force that pushed it right to 399hp. That’s the kind of power we were hoping to make at the end of the project, so mission accomplished, right? Sort of. While it could produce a dyno number to compete with a new Ford, it wouldn’t sustain it for long with exhaust gas temps and smoke output getting high. With a couple data logs on some wide open throttle runs we pinpointed a couple issues. First off, the fuel pressure was dropping from 55-psi to the low 20’s, injection pressure wouldn’t maintain the 2800-psi that was being commanded and lastly a 1700-degree pyrometer reading means melted pistons could be on the horizon.

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Under the hood, not only is the mechanical fuel pump (buried down in the valley) not enough to support our 205cc injectors, they’re 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.
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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.

So, first things first, we needed to tackle the fuel pressure problems. The 1994-1997 model years used a mechanical fuel pump located down in the valley of the motor. This pump us actuated by a small rod that rides on a lobe of the camshaft. While it’s simple technology and it did work, when it comes to moving the kind of volume our new injectors need to stay happy, it just isn’t big enough. Besides, that mechanical factory pump is notorious for premature failure and leaks, 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 application, 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.

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Another upgrade we opted for while torn this far into the fuel system was replacing the factory banjo bolts in the front and rear ports of the cylinder heads. You can see how much larger the fuel ports are within the banjos from Strictly Diesel, which allows for better fuel flow through the head. Eliminating another restriction before and after the injectors.
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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.

Even with an old platform like this, there are still a few 7.3L Power Stroke specialty shops out there, Strictly Diesel of Phoenix, AZ being one of them. Dennis Schroeder, co-owner at Strictly has been doing performance 7.3L and 6.0L fuel systems for over nineteen  years now and has definitely learned a thing or two through the years to make sure they produce the highest quality kit on the market. 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.

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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, so it’ll be overkill for our 450hp plans. Just the way we like it.
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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 our 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.

The beauty behind this kit is it’s use of factory 99-03 7.3L Super Duty Bosch fuel pumps, so you maintain near OE reliability, along with quiet operation and excellent performance. The factory Bosch pump has proven its ability to run 100,000+ miles without fail, so running two pumps in parallel with each other will double fuel volume to supply our larger injectors without giving up reliability. An added bonus to the dual pump kit in this truck, if by chance one pump were to fail, the truck will continue to run on the other pump instead of leaving you stranded. 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.

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The new electric fuel conversion and filtration kit assembled easy and mounted right up on the frame directly behind our transfer case. The bracket allows install 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.
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To properly feed the new dual fuel pumps, the factory pickup inside the tank just wouldn’t cut it so the tank was dropped for the installation of Strictly Diesels 5/8” pick-up tube kit. The new pickup eliminates restriction pre-pumps, so they’ll live a long and happy life without having to pull fuel too hard to maintain pressure to the engine.

These trucks were equipped with dual tanks, but since the factory selector valve will be a major restriction in the system, it will be bypassed completely with the installation of a high flow 5/8” draw straw in our front tank to feed the new dual pumps with. This meant we would 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. However, to extend the overall range of this truck while towing, we opted to install a 44-gallon Trekker fuel tank from Titan in the bed. The Trekker tank system offers an easy to install fuel transfer system with an in-cab controller to monitor tank level and move diesel 5-gallons at a time, so you don’t have to worry about forgetting the pump is on and overfilling the main tank below.

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To make the return to tank plumbing as easy as possible, Strictly 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.
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With the complete fuel system installed (along with a host of other parts we’ll talk about in an upcoming issue) you 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.

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. It should be stated that this complete tank to engine fuel system install isn’t for the faint of heart, it can be rather labor intensive, but we’d dare say it’s a necessary upgrade on  any 94-97 truck looking to support anything over factory injectors. Strictly Diesels kit fit perfectly and comes supplied with excellent step by step instructions, it’s just a time consuming job when it comes to dropping the fuel tank, removing the turbocharger and installing all the new fuel lines, fittings, and hoses.

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Since the factory fuel selector valve to switch from your front tank to the rear tank is a major restriction in the fuel supply, it was bypassed completely. This meant we lost the use of our rear tank, so we opted to install Titan’s new 44-gallon in-bed Trekker tank which now feeds or front main tank.
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Titan pre-plumbs the tank with a built in filter and electric transfer pump that will wire in easily to an in-cab controller. This tank will now transfer fuel into our main tank, extending our range since the front tank will only hold 18-gallons on its own.
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The supplied in-cab controller with our Trekker tank kit is super easy to use and will not only display the current fuel level within the tank, it can be turned on to transfer 5-gallons and automatically shut-off. Eliminating concerns of accidentally leaving the pump running and over filling our lower tank.

While the truck was down for the fuel system install, we also made a bunch of other upgrades to the truck to eliminate some labor in the future but you’ll have to wait for a follow up issue to get those details. We can tell you, with our fuel pressure holding strong at the pre-set 65-psi the truck runs exceptionally well. Of course, the other parts we added are making some of that difference, but we know for certain the injectors are happier getting the fuel volume at the required pressure will keep them running happily for thousands of miles to come.

SOURCES

Strictly Diesel
www.strictlydiesel.com

Titan Fuel Tanks
www.titanfueltanks.com

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