Gasoline EFI vehicles can be either return, electronic returnless, or mechanical returnless type fuel systems.

Return type: A supply line and a return line exists. Fuel is fed to the motor by the return line, and unused fuel is returned back to the fuel tank with the return line.

Electronic Returnless type: Only a supply line exists. The fuel pumps are modulated by the vehicle's computer to supply fuel to the motor based on fuel demands

Mechanical Returnless type: Only a supply line exists. The fuel pumps generally run full time, but the system pressure is maintained by a mechanical regulator located in or near the fuel tank.

Back to top

It is best to ask a motorsports professional, but if you're visiting our site, you might be interested in these models' OEM configurations:

2005+ Chrysler/Dodge LX/LC--mechanical returnless
1986-1998 Ford Mustang--return
1999-2010 Ford Mustang (all models)--electronic returnless
1999-2004 Ford Lightning--return
2011 Mustang GT--mechanical returnless
2010 Camaro--electronic returnless

Back to top

You should consider upgrading your fuel system if you've performed significant engine/power adder upgrades that may exceed the capacity of the original fuel system. To make power you need both air AND fuel!

Back to top

This generally depends on the nature of upgrades in the entire vehicle. While all three fuel system types are capable of supplying fuel for significant power, return type is universally accepted as the most flexible and easy to tune for max power, driveability, and consistency.

If you are making relatively small upgrades to your engine (i.e. supercharger with low boost) then it usually makes more sense to maintain the fuel system type and upgrade the capacity within the constraints of your OEM fuel system type.

High power builds (forged motor + big boost and/or nitrous) should be converted to a return type conversion for maximum performance, enjoyment, and protection of your investment.

Back to top

Both pump types are capable of very large fuel deliveries, but external pumps require significant fuel line plumbing under the vehicle, which leads to higher possibility of leaks and/or damaged lines or components. Conversely, an internal pump setup places the prefilters and the pumps inside the tank, leaving only fuel lines and a single filter outside the tank. Generally speaking, external pumps are more reserved for race only applications, since race cars have requisite fire suppression systems and operate at a track environment, where fire supression personel and equipment is readily available. Additionally, internal pumps are more quiet than external pumps.

Back to top

Most fuel pumps have a brushed DC motor. The reliability of these electric motors is subject to the wear of the brushes and commutator, which is greatly affected by the current that must be passed through these components. (more current = more arcing = more wear = less reliability) A single pump setup requires the entire electrical load of the fuel system be placed on one commutator, which is why large pump motor manufacturers require a controller to reduce the pump speed when less fuel is required. Conversely, in a multi OEM pump configuration, the current is distributed across two or three pumps. Additionally, OEM pumps have millions of hours of development and refinement behind them and are designed to run full time over their entire life. Effectively, a multi OEM pump setup is the most reliable high performance fuel pump configuration on the market.

Back to top

Not necessarily. A standard inertia chassis dynomometer does not create the same load condition that a motor sees off the dyno. A vehicle usually requires 5-10% more fuel on the track (or street) compared to a inertia chassis dynomometer under the same weather conditions. Adverse weather conditions can further affect fuel requirements.

Back to top

What fitting types are used on fuel system hose connections?

AN: Army/Navy, but many in substitute 37° JIC (omits the controlled root radius and class 3 tolerance) Seal is achieved with a 37° taper and seat. No thread sealing is required. Used primarily for connecting hose ends since the nut swivels around the fitting. (instead of hose having to spin)

ORB: O-ring boss. Used to interface female fuel system components to AN connectors, such as fuel rail ends. O-ring accomplishes seal, so no thread sealant is required.

NPT: (pipe thread) A tapered thread, often used as a low cost substitute for ORB, also requires use of a thread sealant to seal spiral leak inherent to NPT design. Always use a teflon based liquid thread sealant on fuel system components with this interface...do NOT use teflon tape!

Back to top

Yes! Characteristics of ANY new fuel system component needs to be figured in the overall tune of the vehicle.

Back to top

E-85 is relatively challenging fuel to properly implement on a modified, high performance vehicle due to it's low specific energy and corrosive nature.

The low specific energy mean that you need MORE fuel to produce the same power with gasoline. The corrosive nature has been found to not be a great concern on high performance automobiles at this point; however, it is important to ensure that your injectors and filters are adequate for E-85 and the entire fuel system undergoes a thorough inspection every 3-6 months.

Back to top

This is the pressure differential between the inlet of the injector and the outlet of the injector. An injector relies on this pressure difference to deliver fuel. The fuel system's job is to provide proper ΔP so that the injector can operate. Different fuel system types have different methods of controlling ΔP and therefore have different behaviors of maintaining ΔP.

Back to top

For detailed information, check out Wikipedia's page on this subject. However, to entertain the performance enthusiast, this is your engine's fuel requirement to make a given amount of power.

Back to top

A fuel pressure regulator's job is to create backpressure on the fuel system. Without a fuel pressure regulator, the system would free flow back to the fuel tank.

Back to top

Boost reference (or manifold reference) is when a regulator's spring chamber is connected to the intake manifold (pressure side) of a vehicle. The intake manifold's pressure is important because it is the injector's outlet pressure. The pressure (or vacuum) in the manifold "assists" the regulator's spring to maintain a constant ΔP in any vacuum or boost condition.

Back to top

An aftermarket regulator may be advantageous over an OEM regulator due to:

-adjustability
-boost reference
-orifice size
-flatter regulation slope

Back to top

Call us! We'll be glad to help you choose a proper fuel pressure regulator for your vehicle.

Back to top

This is not a black and white question. The "correct" answer is: "within the ratings of the injector AND the fuel pump."

The trick is that fuel pumps are rated over a wide range and injectors, while rated at a specific ΔP, are able to work effectively over a wide range as well. A nominal answer would be 40 psi, and this is what we recommend if you're building your fuel system from scratch.

If you set a high fuel pressure, you are effectively requiring the pumps to operate under more load. Therefore, the pumps transport less fuel volume while requiring more electrical current, so their life expectancy is reduced. However, your fuel injectors will "act" larger than normal, since more fuel can be forced through their orifice when they open.

If you set a low fuel pressure, you have reversed the above condition. The pumps work with less load, so they pump more volume and the injectors "act" smaller.

Additionally, fuel pressure requirements are also highly depenendent on whether you're boost referencing your fuel system or not.

Which is right for you? Unfortunately, this question isn't something that can be answered with a simple FAQ section. It depends on your engine, budget, expections, and goals. Give us a call and we'll be glad to assist.

Back to top

1. Disconnect the boost reference line and plug the open manifold vacuum line. Leave the regulator boost port exposed to atmosphere.

2. Turn on the car, allow idle to stabilize, and adjust the regulator until the gauge reads the desired fuel pressure. (this is called "base fuel pressure")

3. Connect the boost reference line to the regulator's boost reference port and observe the fuel pressure to drop equivalent of your engine's vacuum. Note that fuel pressure is measured in psi, and vacuum is typically measured in inches of Mercury [in Hg] An easy "rule of thumb" conversion is to cut the in Hg is half to get psi.

i.e.. 22 in Hg = ~11 psi (it is really 10.80539 psi if you want to get "carried" away)

Back to top

Orifice size and spring rate. Build quality, operating loads and stress, material choices, and flow characteristics can affect wear and stability of a regulator over time.

Back to top

Connectivity to larger fuel lines and to add provisions for adding a regulator. In some rare cases, it is REQUIRED to run higher fuel pressures since our rails have stiffer tabs. Additionally, many people consider it a cosmetic upgrade. (big power means you need big fuel)

(80 psi of fuel pressure generates about 70 lbs of upward force on EACH fuel rail)

Back to top

Our fuel rails are the ONLY rails on the market that are designed specifically for each application from scratch. All other manufacturers rails use a generic cross section that is adapted to each application. Our rails are more expensive, but offer the best fit and finish in the business.

Back to top

-8 ORB (o-ring) on the ends, and two 1/8 NPT (pipe thread) ports on the top of one side to accomodate either fuel supply for nitrous or a fuel pressure gauge (or remote for cockpit mounted fuel pressure gauge)

Back to top

Yes, if the factory fuel rails had a sensor, our rails include provisions for the sensor in the same position and orientation as the OEM intended.

Additionally, if you wish to delete the sensor, (for a return type system) we also have block off kits in stock

Back to top

Yes, you can use our GT500 rail spacers to accommodate long injectors IF your supercharger inlet configuration allows clearance. Our GT500 fuel rails are the same height as the OEM rails; however, our mounting tabs are thicker.

Contact us or the supercharger manufacturer to inquire about fitment. We work with most of the supercharger manufacturers for compatibility information.

Back to top

Yes, with the OEM intake manifold and a turbo/centrifugal blower, our rails can be used with tall injectors; however, the end user is responsible for providing spacers (washers) to move the rails up by about 10mm.

For more detailed information contact us at 919-550-0700

Back to top

There are simply too many variables to draw the line at a specific power level depending on the application. A triple pump hat from Fore Precision provides the same performance as a "2000hp" external pump.

Back to top

If you are running an electronic returnless system, we recommend Walbro F100000128 (GT40 supercar pumps) and if you are running a mechanical returnless or a return type system, then we recommend Walbro GSS340 or GSS342.

Back to top

Again, this is hard to say because there are several variables that can tip the scale. However, a general rule is that two pumps can handle anything you can do with pump gas.

Back to top

We generate a suction with an integral venturi pump. It uses a high velocity jet to create a low pressure region, which draws fuel from the non-pump side of the fuel tank.

Back to top

No. Every Fore Precision fuel hat retains complete use of the OEM fuel tank functions. Modern vehicles that we accomodate with our fuel hat lineup do not need larger tank vents to operate correctly.

Back to top

Yes, this is possible, contrary to popular internet speculation. There is no problem using a GT40 (Walbro F100000128) supercar pump in a return configuration. However, we reccomend using the Walbro GSS 340/341/342 as appropriate in a return configuration since they are cheaper and better performance than the GT supercar pump.

While GSS pumps may operate in a electronic returnless configuration, we advise against it since voltage tables are not well deveoped and general market experience is low. In an electronic returnless configuration, the GT40 supercar pumps are recommended first.

Back to top

Certainly. We do recommend one of our anodized fuel hats for E-85 use.

Back to top

Yes. This is the most commonly overlooked requirement for upgrading a fuel system. Not only does this cost the pumps significant performance, but it is quite common to melt down OEM wiring if a new pump system is installed.

Back to top

Run your fuel pumps at normal vehicle voltage. This is where these pumps are designed to operate best. At higher voltage, efficiency drops significantly and perfomance becomes inconsistent, and the pumps become unreliable.

At 40 psi, running a pump at 13 volts vs 17 volts requires 65-70% more power and delivers only 25-30% more volume. If any type of transformer device is used to step up voltage, overall efficiency is further reduced.

Back to top

It depends on which hat you purchased. You may check on the particular hat's product page on this website, or call us at (919) 550-0700 for detailed information.

Back to top

No. These pumps may be run full speed all the time. However, some customers choose to run two pumps full time and activate the third pump only when needed. (i.e. with a pressure switch, or activate with nitrous arming)

Back to top

A filter's "micron rating" is the filter's screen size. For example, a 100 micron filter will block all particles larger than 100 microns and particles smaller than 100 microns may pass through the filter. A more fine filter (smaller micron rating) has more restriction; however they are prone to becoming clogged very quickly, leading to even more restriction after some use.

Your fuel system should have two fuel filter stages. The first filter stage is a course filter designed to protect the pump. You should not use a fine filter before the pump since it will reduce inlet head, which can affect pump performance. All Fore Precision fuel hats come with 40 micron filters to protect the pumps. Most external pumps require a 100 micron filter before the pumps.

Next, a fine filter should be installed before the injectors (and after the pump) to protect the injectors. Most fuel injector manufacturers require 10 micron filtration before the injectors.

Back to top

If you are using a Fore Precision fuel hat, it comes with 40 micron fiters for the pumps, that are installed inside the fuel tank. (on the ends of the pumps)

Additionally, you will need ONE 10 micron external filter to protect the injectors.

Back to top

Most of the time, fuel lines size requirements are overstated. For all of our fuel hats, a -8 line for feed and return is adequate.

Back to top

ALL aftermarket fuel lines emit some smell. Teflon lined fuel lines are usually best, but end fitting selection is very limited and very expensive. Our customers have had the best results with Aeroquip lines. Our personal favorite is Aeroquip Startlite hose, since it is sanctioned by most racing organizations, lightweight, non abrasive, and easy to install.

Back to top

Positive Pressure Relief Valve. It is a dual function device. It contains a check valve and a relief valve. The PPRV's purpose is to hold fuel in the fuel lines after engine shutdown. The relief function is to allow for expansion of the fuel in the lines/rails when the fuel stops moving and is heated by the motor.

There are several different types of PPRVs installed in Ford automobiles. The models we have tested "blow off" pressure around 65-70 psi. The problem with attempting to retain a PPRV on a vehicle with a high capacity fuel system is the loss across the PPRV, since they are designed for a relatively low flow rates.

We have measured the loss from ONE pump at 40 psi to be about 2psi, which is fine. However, when we added the second pump, the loss was 14 psi, which is unacceptable. This loss not only hinders fuel system performance, but makes tuning the fuel system very difficult and ultimately affects driveability.

Back to top

Fuel Pump Driver Module. This is a PWM DC motor controller that handles the fuel pumps. It is very similar in design to an electronic speed controls used for radio controlled cars. (for brushed motors)

These modules are used by the OEM to control ONE high performance pump, or a pair of low performance pumps. ('03-'04 Mustang Cobra) Some higher performance cars have two FPDMs from the factory, since they have two pumps.

If you add a second high performance pump, or replace two low performance pumps with a pair of high performance pumps, an upgrade to the FPDM is normally required. There are certain low power cases that don't require an FPDM upgrade, but call to discuss.

There are three methods to upgrading the FPDM:

1. Stage 1 or 2 upgrade, from Zone 5 Performance.
2. Modify the OEM wiring harness to accept two or three FPDMs
3. MDM (Mega Driver Module) from Zone 5 Performance

Back to top

Fuel Rail Pressure Sensor. It is a dual input sensor with a diaphragm in between the inputs. One input is the manifold pressure, and the other input is fuel pressure. The FRPS sends the difference (or ΔP) between these two inputs, which is generalized as the "fuel pressure" when viewing datalogs. This differs from a standard fuel pressure gauge that displays ONLY fuel pressure without regard to manifold pressure. (or vacuum)

A "blown" FRPS indicates that the diaphragm between the inputs has ruptured, typically from pressure spikes in the fuel system due to tuning, fuel system configuration, and driver inputs.

Back to top

Duty cycle is an indicator of how hard the FPDM is working. (not necessarily the pumps) It is normally reported as a decimal value between 0 and 1, where 1 indicates 100%. The FPDM is a PWM (pulse width modulated) controller, so it "switches" on and off at a high frequency. The duty cycle of "1" (or 100%) means the FPDM is continuously ON and not switching; therefore, the FPDM is working at 100%.

Back to top

We recommend the Ford GT40 supercar pumps (Walbro #100000128) since their voltage tables are well developed and many shops/tuners have experience with these pumps. While the Walbro GSS340/1/2 pumps are indeed capable of operating in an electronic returnless configuration, it is generally not worth the trouble. Few shops have found success in making the GSS series pumps work in an electronic returnless configuration.

Back to top

An MDM is an aftermarket pump controller that accepts the pump output from the FPDM, requires an additional power source that can drive a high current pump configuration. Visit Zone 5 Performance for more details.

Back to top

This is better addressed on a case by case basis. Generally speaking, a return type fuel system has more capacity and is easier to tune, but this does not necessarily mean that it is the best approach. Give us a call for more detailed information about your build.

Back to top

Just like 6.7, this is best addressed on a case by case basis. If the vehicle's build goals are mild or modest, then keeping the electronic returnless type system may be most cost effective, especially if the tuner is experienced in similar type builds. Give us a call more for more information, and we'll be glad to help you explore your options.

Back to top

Fuel Pump Control Module. It serves the same function as the FPDM, but the context of FPCM normally relates to GM vehicles.

Back to top