Racetronix 1999+ LS1 Fbody High-Performance Fuel Pump System

The 1999 & up LS1 F-body cars have a pump that is inside a plastic fill-bucket. The fill-bucket is equipped with two inlets on the bottom.  The equalization checkvalve is used to fill the bucket when the level of fuel in the tank is greater than in the bucket. The equalization checkvalve does not allow fuel to exit the bucket. The venturi system's inlet is a combination checkvalve and powered suction system. The factory pump supplies pressurized fuel via a small tube which feeds a calibrated jet inside the venturi system. This jet of fuel shoots across the base of  the checkvalve inlet thereby creating a suction effect which draws more fuel from the bottom of the tank through the filter sock. This venturi system keeps the bucket full all the time even when the fuel tank is almost empty. A full bucket keeps the pump immersed in fuel regardless of the tank level so that when the tank is low on gas and you are doing some hard cornering or acceleration the pump does not run dry and start aerating (air bubbles) the fuel. This happens as the fuel sloshes from side to side in the tank leaving the center low on fuel.  This can cause detonation and possible engine damage. The 99+ F-LS1 cars with plastic tanks have no baffling in them so the bucket is very important. The bucket also allows the car to operate with lower fuel levels in the tank due to its scavenging effect. The fill-bucket improves motor crank-to-run time as the priming time is reduced under most conditions. The return line feeds the pressure regulator on the fuel module which diverts fuel back into the bucket so that the unused fuel also helps keep it full at all times. Keeping the pump constantly immersed in gas within the bucket can extend the pump's life by not allowing it to be exposed to open air. Open air within the tank contains moisture and in time will cause the pump to rust / seize up especially if left to sit for long periods of time without the tank topped-up (i.e. winter storage).

The Racetronix pump assembly is designed to fit in the factory pump location. The Racetronix pump is equipped with a factory type fuel tube not a rubber hose. This fuel tube is important as when the fuel module is placed back in the tank it must bend sharply which can cause standard rubber hose to kink. This fuel tube is much more resistant to the solvents in today’s gas and it will not crack, split, swell and collapse like a rubber hose. This is why G.M. uses them as OE equipment.

The Racetronix pump assembly is equipped with an outlet which supplies the factory venturi system which is required to keep the factory system functional! All other pump solutions to date do not have this feature which requires a hole be punched in the bottom of the fill-bucket thereby dangerously disabling its functionality.

The Racetronix fuel module is equipped with a one-piece soldered wiring harness made from mil spec. Teflon silver-plated wire. This is the same type of wire used at the factory as Teflon is the most resistant to deterioration when exposed to gas. This harness has a Walbro connector at one end and a GM F-LS1 connector at the other which plugs directly inside the factory connector. No crimping, splicing or wiring adapters are required. A truly plug & play wiring solution. Due to the age of some F-LS1 cars much of the in-tank connectors are black / corroded. The Racetronix harness replaces all these questionable components.

The Pumps

The Racetronix F-LS1 pump assembly is based on Walbro gerotor pump technology utilizing the most powerful armature and gear set currently available. Walbro has set the industry standard in high-performance in-tank pumps. Walbro pumps are QS9000 certified and are used as OE equipment in many production performance vehicles such as the C5 Corvette. Walbro's gerotor design is able to maintain high pressures while providing high volumes as well. This is done by squeezing the fuel out between two gears instead of pushing it like most factory vane pumps do. (i.e. factory F-LS1 pump). This positive displacement design makes high-performance Walbro pumps small, light weight, quiet, efficient and reliable. Tests in the field have proven the Racetronix F99+ system will support upwards of 600RWHP and 700RWTQ in some applications. This system in combination with Racetronix's upcoming PnP fuel rail-mounted return regulator system will extend the pump systems HP support and help stabilize fuel pressure at the motor.

The Wiring Harness

All fuel pumps are  voltage sensitive, the lower the voltage the lower the fuel volume. Gerotor pumps exhibit a significant increase in fuel volume with increased supply voltage. A Walbro pump's average fuel volume increases over 18% by increasing the supply voltage from 12 to 13.5 volts. The factory harness is marginal at best for supplying a factory pump with enough voltage to perform well. This is why the 'hot wire' modification is so popular. Replacing the factory pump with a high-performance pump can easily double the current demand under W.O.T. pressures.  The voltage drop in the factory harness increases proportionally to the current demands of the pump. Racetronix has documented tests where the voltage drop in a factory harness has caused over a 25% drop in fuel pump volume. The Racetronix harness uses heavy 10 gauge copper wire to reduce voltage-drop to very low levels. The factory gauge of wire used is three gauges thinner. The power feed comes off the back of the alternator where voltage is highest. It then runs through a Delphi weatherproof fuse holder and then to the back of the car. The Racetronix harness uses three-position male and female Delphi Weatherpack connectors which plug in-line with the factory harness at the back of the tank. No cutting or splicing is required. A Siemens weatherproof 40 amp rated mil-spec. relay is used. These relays have silver plated contacts and are the best money can buy so that you can be guaranteed to have trouble-free operation. The Racetronix harness has a redundant ground upgrade as it is necessary to improve the harness on the negative side of the pump's supply as well. All the harness connections are crimped using certified Delphi crimpers and are soldered as well. All the harnesses Racetronix has seen to date from the competition, are not soldered. Racetronix supplies a spare ATC fuse, black vinyl wire ties, silicon grease and mounting hardware with each kit. The optional battery to body ground upgrade kit is not included in this kit. This kit upgrades the under-rated ground wire running from the battery to chassis. It includes a crimped and soldered piece of high strand count 8 gauge copper wire and brass battery nuts with accessory taps.

The Racetronix harness comes equipped with an interface connector just after the relay. This connector in combination with a supplied connector set (rated 30 amps) allows for easy plug and play addition of a pump booster / voltage amplifier such as the MSD or KB unit. These voltage amplifiers / boosters will allow the Racetronix single in-tank pump system to support upwards of  700RWHP+ when run at 16 volts. This configuration offloads the excessive current draw placed on the factory wiring onto the heavy gauge Racetronix harness system.

This fuel pump system will be fully compatible with Racetronix's upcoming PnP rail-mounted fuel pressure regulator system. The combination of these two systems will support VERY high HP levels using factory lines while maintaining ultra stable fuel pressure. Long gone are the days of sumped tanks, heavy braided lines, expensive noisy and unreliable external pumps!

The pumps used in the F-LS1 kits are not standard issue Walbro pumps. They have been modified.