Fuel Supply Component Description. Cadillac Eldorado 1999

For 1990-2009 cars only

Makes 🢒 Cadillac 🢒 1999 🢒 Eldorado 🢒 Engine 🢒 Engine Controls - 4.0L and 4.6L 🢒 Fuel Supply Component Description

Caution: This vehicle is equipped with Supplemental Inflatable Restraint (SIR). Refer to the Cautions in the On-Vehicle Service and the SIR Component and Wiring Location view in the Supplemental Inflatable (SIR) System before any performing service on or around SIR components or wiring. Failure to follow the Cautions could result in possible air bag deployment, personal injury, or otherwise unneeded SIR system repairs.

Notice: Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.

On-Board Refueling Vapor Recovery System (ORVR)


(1)	Fuel Tank Fill Pipe Assembly
(2)	EVAP Emissions RR Hose Assembly
(3)	Fuel Tank Fill Pipe Hose Connection
(4)	Fuel Tank Assembly

1999 Eldorado and Deville vehicles built after March 1, 1999 will have fuel system components identified with RPO's NAC/RB1. These vehicles will feature the On-Board Refueling Vapor Recovery System (ORVR).

The On-Board Refueling Vapor Recovery System (ORVR) is an on-board vehicle system to recover fuel vapors during the vehicle re-fueling operation. The flow of liquid fuel down the filler neck provides a liquid seal which prevents vapor from leaving the fuel system by transporting vapor to the EVAP canister for use by the engine. The purpose of (ORVR) is to prevent re-fueling vapor from exiting the fuel tank filler neck.


(1)	EVAP Canister
(2)	EVAP Pipes
(3)	Fuel Filler Pipe
(4)	Check Valve
(5)	Modular Fuel Sender Assembly
(6)	Fill Limiter Vent Valve
(7)	Pressure Relief Valve

The ORVR components include:

•

Fuel Tank

•	Fuel Tank Filler Pipe

•	EVAP Canister

•	Vapor Lines

•	Check Valve

•	Modular Fuel Sender (fuel tank pressure sensor located on modular fuel sender cover)

•	Fuel Limiter Vent Valve (FLVV)

•	Pressure Relief Valve

•	Vapor Recirculation Line

•	Variable Orifice Valve

Listed below are the ORVR system components with a brief description of their operation:

•	Fuel Tank - contains the modular fuel sender, fuel limiter vent valve, and a roll over valve integral to the modular fuel sender.

•	Fuel Filler Pipe - the pipe which carries fuel from the fuel nozzle to the fuel tank.

•	EVAP Canister - the EVAP canister receives refueling vapor from the fuel system, stores the vapor and releases the vapor to the engine upon demand.

•	Vapor Lines - transports fuel vapor from the tank assembly to the EVAP canister.

•	Check Valve - the check valve limits fuel "spit-back" from the fuel tank during the refueling operation by allowing fuel flow only into the fuel tank. This check valve is integral to the fuel tank filler inlet.

•	Modular Fuel Sender Assembly - this assembly pumps fuel to the engine from the fuel tank.

•	Fill Limiter Vent Valve (FLVV) - this valve acts as a shut-off valve located in the fuel tank and has the following functions:

-	Controls the fuel tank fill level by closing the primary vent from the fuel tank.

-	Prevents fuel from exiting the fuel tank via the vapor line to the canister.

-	Provides fuel-spillage protection in the event of a vehicle rollover by closing the vapor path from the tank to the EVAP canister.

•	Pressure/Vacuum Relief Valves - the pressure/vacuum relief valves provide venting of excessive fuel tank pressure and vacuum. The pressure relief valve is located on the top center of the tank. The vacuum relieve valve is integral to the fuel cap located at the top of the fill pipe.

•	Vapor Recirculation Line - The vapor recirculation line is used to transport vapor from the fuel tank to the top of the fill pipe during the refueling to reduce vapor loading to the Enhanced EVAP canister.

•	Variable Orifice Valve - The variable orifice valve regulates venting to the canister when the FLVV is in its shut-off condition.

Fuel Tank


(1)	Modular Fuel Sender -- Fuel Level Sender
(2)	Fuel Tank Strap Bolt
(3)	Fuel Tank Straps
(4)	Fuel Tank

The fuel storage tank is made of high density polyethylene and is located in front of the rear wheels. It is held in place by two metal straps and bolts attached to the under body of the vehicle. The tank shape includes a sump to maintain a constant supply of fuel around the fuel pump strainer during low fuel conditions or aggressive maneuvers. The tank also contains a fuel vapor vent valve with roll-over protection.

The modular fuel sender is located inside the fuel tank.

Fuel Tank Filler Pipe

To help prevent refueling with leaded fuel, the fuel filler pipe has a built-in restrictor and deflector. The opening in the restrictor will accept only the smaller unleaded gasoline fuel nozzle which must be fully inserted to bypass the deflector. The filler pipe is attached to the tank by a section of hose and two hose clamps. The tank is vented during filling by an internal vent tube inside the filler pipe.

Fuel Filler Cap


(1)	Fuel Filler Cap
(2)	Fuel Tank Filler Pipe
(3)	Fuel Filler Door
(4)	Fuel Filler Cap Tether

The fuel tank filler pipe is equipped with a turn to vent screw on type cap which incorporates a ratchet action to prevent over-tightening. The filler cap is located inside the fuel filler door.

The turn to vent feature allows fuel tank pressure relief prior to removal. Instructions for proper use are imprinted on the cap cover. A vacuum safety relief valve is incorporated into this cap.

The cap has a tether attached to the fuel filler door.

Notice: Use a fuel tank filler pipe cap with the same features as the original when a replacement is necessary. Failure to use the correct fuel tank filler pipe cap can result in a serious malfunction of the fuel system.

Modular Fuel Sender - Fuel Level Sensor


(1)	Fuel Tank Pressure Sensor
(2)	Fuel Pipes
(3)	Fuel Pump
(4)	External Fuel Sender Strainer
(5)	Fuel Level Sensor Assembly
(6)	Fuel Sender Cover

The modular fuel sender assembly mounts to a non - threaded locking ring (cam lock ring). The modular fuel sender contains a spring loaded reservoir that has a exterior inlet strainer, electric fuel pump, and pump strainer that maintains contact with the fuel tank bottom. This design provides:

•	Optimum fuel level in the integral fuel reservoir during all fuel tank levels and driving conditions.

•	Improved tank fuel level measuring accuracy.

•	Improved coarse straining and added pump inlet filtering.

•	More extensive internal fuel pump isolation for noiseless operation.

The modular fuel sender assembly consists of the following major components: A fuel sender cover assembly, a fuel sender, fuel pipes (above cover), a fuel sender support assembly, a fuel pump, a fuel pump strainer, a fuel pump reservoir, a fuel sender strainer, and a fuel level sensor assembly.

Modular Fuel Sender - Fuel Flow


(1)	Fuel Feed
(2)	Fuel Return
(3)	Convoluted Fuel Tube (Flex Pipe)
(4)	Secondary Umbrella Valve
(5)	External Fuel Pump Strainer
(6)	Fuel Flow from External Strainer
(7)	Fuel Pump Strainer
(8)	Fuel Pump

The modular fuel sender assembly maintains optimum fuel level in the reservoir (bucket). Fuel entering the reservoir (bucket) is drawn in by:

•	The first stage of the fuel pump through the external strainer.

And/Or

•	The secondary umbrella valve,

•	The return fuel pipe, whenever the level of fuel is below the top of the reservoir.

The fuel pump used in this system is part of the fuel sender assembly. The fuel pump lower connector assembly prevents the transmission of vibration and noise generated by the pump to the fuel tank.

Fuel enters the lower inlet port (secondary umbrella valve located inside of lower inlet port) of the electric fuel pump after being filtered by the external fuel strainer, and the fuel pump strainer. The initial function of the pump is to fill the reservoir.

The second stage separates vapor from the fuel in the pump. This vapor separation maximizes hot fuel handling and permits the vapor to return to the fuel tank at lower pressure and temperature. By creating positive fuel pressure, the pump then discharges the liquid fuel into the third stage of the pump. The pump outlet allows the fuel volume to flow through a check valve into the fuel pump flex pipe. The check valve seat is molded inside the connector body. The check valve body and retainer are assembled into the connector body. The check valve restricts fuel back flow.

After the fuel pump flex pipe, the fuel exits the assembly through the fuel feed output fitting on the molded cover. The cover also contains a fuel return provision which connects to one of three hollow support pipes.

The quick-connect end fittings allow fuel feed and fuel return. Electrical power to the fuel pump enters the unit by way of a connector which is attached to the cover. An internal wire harness and connector assembly connects to the fuel pump and level sensor. The modular design adds additional functions that improve accuracy and ensure constant, steady fuel supply under all conditions. All components and subassemblies of the modular sender attach to a common cover and access the fuel tank through a single opening.

Modular Fuel Sender Assembly Component Description

The modular fuel sender assembly is spring loaded to the bottom of the fuel tank. This bottom referencing permits continuous fuel pickup and accurate fuel level sensing. The reservoir assembly is the lower section of the modular unit which encases the fuel pump. A retainer attaches to the top of the reservoir. Fuel is captured and maintained in reservoir at a level sufficient to submerge pump.

Two quick-connect pipe end fittings are molded onto the cover of the modular unit for ease of unit removal from the fuel tank. These quick-connect end fittings allow fuel feed and fuel return.

Modular Fuel Sender Serviceable Components


(1)	Fuel Tank Pressure Sensor
(2)	External Fuel Sender Strainer
(3)	Fuel Level Sensor Assembly

The serviceable components on the modular fuel sender are the fuel sender strainer, the fuel level sensor assembly, and the fuel tank pressure sensor.

The strainer acts as a coarse filter to: filter contaminants, separate water from fuel, and to provide a wicking action that helps draw fuel into the fuel pump.

Fuel stoppage at the strainer indicates that the fuel tank contains an abnormal amount of sediment or water. Therefore, the fuel tank should be removed, cleaned, and the filter strainer replaced. Refer to Fuel System Cleaning .

Fuel Level Sender Assembly

The fuel level sender attaches to the outside of the reservoir and measures the amount of fuel in the tank. The fuel level sender consists of the following components: the rheostat, the float, and the float arm. The assembly converts changes in the fuel level to a variable electrical signal used to drive a gauge in the instrument cluster. An electrical harness attached to the fuel sender cover connects the rheostat to the vehicle's wiring harness.

Fuel Pump

The electric fuel pump is a fuel pump located inside the modular fuel sender. The electric fuel pump operation is controlled by the PCM through two fuel pump relays.

In-Line Fuel Filter


(1)	In-Line Fuel Filter
(2)	Fuel Tank

The in-line fuel filter is located to the left of the fuel tank. The in-line filter is used in the fuel feed pipe ahead of the fuel injection system. The filter element is made of paper, and is designed to trap particles in the fuel that may damage the injection system. Quick-connect type fittings are used at both ends of the filter.

Fuel Pump Relay

The fuel pump relay allows the fuel pump to be energized by the PCM. When the ignition is first turned On, the PCM energizes the fuel pump relay for two seconds. This allows the fuel pump to run for two seconds and build up fuel pressure for cranking. The PCM then waits for ignition reference pulses from the Ignition Control Module (ICM). Once the PCM sees references pulses, the PCM energizes the relay to run the fuel pump.

A faulty fuel pump relay may cause long cranking times and should set a DTC.

Fuel and EVAP Pipes


(1)	EVAP Pipe
(2)	Fuel Feed Pipe
(3)	Fuel Return Pipe
(4)	Fuel Return Pipe Retainer
(5)	Fuel Feed Pipe Retainer

The fuel feed, return, pipes carry fuel to and from the fuel rail as part of the fuel delivery system. The EVAP pipes carries fuel vapors for the EVAP components. Retaining clips hold the pipes together and provide a means for attaching the pipes to the vehicle. Quick-connect type fittings are used at the ends of the fuel feed and return and at the in-line fuel filter. They are described below. Sections of the pipes that are exposed to chafing, high temperature or vibration are protected with heat resistant rubber hose and/or coextruded conduit.

Nylon Fuel Pipes

Nylon fuel pipes are designed to perform the same function as the steel or rubber fuel pipes they replace. Nylon pipes are constructed to withstand maximum fuel system pressure, exposure to fuel additives, and changes in temperature. Both fuel feed and fuel return pipe size is 5/16 of an inch ID. The EVAP pipe from tank to canister size is 1/4 of an inch ID and from canister to engine is 5/16 of an inch OD. The vacuum signal pipe is 1/4 of an inch ID. Nylon fuel pipes are somewhat flexible and can be formed around gradual turns under the vehicle. However, if forced into sharp bends, nylon pipes will kink and restrict fuel flow. Also, once exposed to fuel, nylon pipes may become stiffer and more likely to kink if bent too far. Special care should be taken when working on a vehicle with nylon fuel pipes.

Caution: In order to Reduce the Risk of Fire and Personal Injury:

•	If nylon fuel pipes are nicked, scratched or damaged during installation, Do Not attempt to repair the sections of the nylon fuel pipes. Replace them.

•	When installing new fuel pipes, Do Not hammer directly on the fuel harness body clips as it may damage the nylon pipes resulting in a possible fuel leak.

•	Always cover nylon vapor pipes with a wet towel before using a torch near them. Also, never expose the vehicle to temperatures higher than 115°C (239°F) for more than one hour, or more than 90°C (194°F) for any extended period.

•

Before connecting fuel pipe fittings, always apply a few drops of clean engine oil to the male pipe ends. This will ensure proper reconnection and prevent a possible fuel leak. (During normal operation, the O-rings located in the female connector will swell and may prevent proper reconnection if not lubricated.)

Quick-Connect Fittings

Quick-connect type fittings provide a simplified means of installing and connecting fuel system components. There are metal collar and plastic types of quick-connect fittings used at different locations in the fuel system. Each type consists of a unique female socket and a compatible male connector. O-rings, located inside the female socket, provide the fuel seal. Integral locking tabs or fingers hold the fittings together. The quick-connect fittings used at the fuel filter and other connections at the rear of the vehicle have hand re-leasable locking tabs. The fittings used at the engine fuel pipes have locking tabs that require a special tool to release.