Fuel Delivery System

Fuel Tank And Fuel Pump Module View.:

WARNINGS:
^ To help avoid personal injury when a vehicle is on a hoist, provide additional support for the vehicle on the opposite end from which components are being removed. This will reduce the possibility of the vehicle falling off the host. Make sure hoist does not contact fuel or brake lines.

^ To reduce the risk of fire and personal injury, it is necessary to relieve the fuel system pressure before servicing fuel system components (refer to fuel system pressure relief).

^ Do not allow smoking or the use of open flames in the area where work on the fuel system is taking place. Anytime the fuel system is being worked on, disconnect the negative battery cable, except for those tests where battery voltage is required.

FUEL SYSTEM
All new Saturn vehicles are certified by the United States Environmental Protection Agency (EPA) as conforming to the requirements of the regulations for the control of air pollution from new motor vehicles. This certification is contingent on certain adjustments being set to factory standards. In most cases, these adjustment points either have been permanently sealed and/or made inaccessible to prevent indiscriminate or routine adjustments in the field. For this reason, the factory procedure for temporarily removing plugs, caps, etc., for purposes of servicing the product must be strictly followed and, wherever practical, returned to the original intent of this design.

The Saturn fuel system is comprised of a polyethlene fuel storage tank. This tank is equipped with a submersible electric fuel pump, reservoir, and fuel level sending unit module attached at the top of the fuel tank. This module is held in place with a cam-lock ring and sealed with a rubber 0-ring seal. Fuel is drained from the tank by removing the filler tube at tank.

Fuel enters the fuel storage tank through a lead-tin plated steel filler neck attached to the tank with a short section of rubber hose. This system is sealed from the environment with a fuel filler cap.

Fuel is delivered from the pump to the engine and from the engine back to the tank by way of nylon fuel lines. Before entering the engine, fuel passes through an in-line fuel filter.

Fuel vapor generated within the fuel storage tank is stored in a charcoal EVAP vapor canister where it is later purged and consumed by the engine.

FUEL PUMP MODULE AND GAUGE SENDING UNIT
The pump module has three places to attach hoses. One line is for the fuel feed line. The second line is connected to the EVAP vapor canister, to keep fuel vapor from getting into the air. The third line is used as a fuel return line to the tank.

The fuel gauge sending unit is attached to the side of the fuel pump module. It is held in place with a snap lock.

When a fuel gauge sending unit is removed, always make sure to replace the pump module to fuel tank 0-ring seal and any power or ground leads that were removed or damaged.

FUEL LINES
Fuel lines cannot be spliced. If they are damaged, they must be replaced with the same type of line.

1995 vehicles have a stone deflection shield integral with the fuel line clip. The fuel line clip retaining nut must be protected from damage caused by stones and other foreign debris.

FUEL FILTERS
Fuel filters fall into two categories: in-line filters and sending unit filter socks.

In-Line Filters - The in-line filter can be found in the fuel feed line under the vehicle and mounted on the driver's side of engine compartment frame rail.

In-Tank Fuel Filters - A woven plastic filter is located on the lower end of the fuel pickup tube in the fuel tank. This filter prevents dirt from entering the fuel line and also stops water, unless the filter becomes completely submerged in water. This filter is self-cleaning and normally requires no maintenance. Fuel stopage at this point indicated that the fuel tank contains an abnormal amount of sediment or water; the tank should therefore be thoroughly cleaned.

ELECTRIC FUEL PUMP
The electric fuel pump used on Saturn vehicles is in the fuel tank and is serviceable.

If the fuel system is suspected of delivering an in improper amount of fuel, it should be inspected and tested in the vehicle.

FUEL PUMP RELAY
To control fuel pump operation, a fuel pump relay is used. When the ignition switch is turned to the RUN position, the fuel pump relay activates the electric fuel pump for 1.5 to 2.0 seconds to prime the injector. If the PCM does not receive reference pulses from the crank position sensor and ignition module after this time, the PCM signals the relay to turn off the fuel pump. The relay will once again activate the fuel pump when the PCM receives reference pulses.

CONTROL OF FUEL VAPORS

Evaporative Emissions Hose Routing:

The evaporative emission control system (BECS) limits fuel vapor escape into the atmosphere. The system transfers fuel vapor from a sealed fuel tank, through a single vapor pipe, to an activated carbon (charcoal) storage device (EVAP vapor canister) that stores the vapors when the vehicle is not operating. When the engine is running with coolant temperature above 70°C (158°F), the vehicle speed above -one mile per hour, and more than four per cent TPS, fuel vapor is purged from the carbon element by intake air flow and consumed in the normal combustion process.

Fuel vapors from the fuel tank are purged and flow into the EVAP vapor canister tube labeled fuel tank and are absorbed by the carbon. The EVAP canister is purged when the engine is running above idle speed. A timed vacuum source is applied to the EVAP vapor canister tube labeled EVAP canister purge to draw fresh air through the air inlet, at the top of the EVAP canister. This air flows through a tube to the bottom of the EVAP canister and forces the vapors out of the EVAP canister purge line.