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Mazda RX7. Manual - part 37

FUEL EVAPORATION SYSTEM

Article Text

1983 Mazda RX7

For www.iluvmyrx7.com

Sunday, August 26, 2001 04:58PM

ARTICLE BEGINNING

1983 Fuel Evaporation Systems
MAZDA ROTARY ENGINE

RX7

DESCRIPTION

System prevents escape of fuel vapors into atmosphere.
Components consist of a non-vented fuel tank with integral vapor
separator, vapor valve, check and cut valve (located at fuel tank),
charcoal canister, air vent solenoid valve, purge valve and
connecting hoses.

OPERATION

When engine is not running, fuel vapors formed in fuel tank
pass through vapor valve. Those vapors that do not condense to liquid
fuel are routed through vent lines to charcoal canister where they
are adsorbed. When engine is running, filtered air is drawn into the
system through the air cleaner, mixed with gases and vapors that blow
by the rotor and are drawn through purge valve and into intake runner
to be burned. The purge valve operates as the PCV and check valve.

AIR VENT SYSTEM

An air vent solenoid on carburetor prevents carburetor bowl
evaporated fuel from collecting in the intake manifold after hot
engine shut off. With ignition off, the solenoid closes an air vent
in the carbon canister, trapping the evaporated fuel.

Fig. 1: Mazda RX7 Check and Cut Valve

FUEL EVAPORATION SYSTEM

Article Text (p. 2)

1983 Mazda RX7

For www.iluvmyrx7.com

Sunday, August 26, 2001 04:58PM

Fig. 2: Mazda RX7 Air Vent and Fuel Evaporation System

CHECK & CUT VALVE

This valve has 3 functions: When fuel tank pressure becomes
too high, valve releases pressure to atmosphere. When vacuum becomes
too high, valve allows air into tank to prevent tank from collapsing.
If vehicle is overturned, valve prevents fuel leakage by sealing the
line with a check ball.

TESTING

EVAPORATIVE LINE CHECK

1) Disconnect evaporative hose from canister. Connect
detached hose to a "U" tube type pressure gauge filled with water.
2) Gradually apply low air pressure into "U" tube so that
difference of water level reaches 14" (356 mm).
3) Bind inlet of "U" tube and leave bound for 5 minutes. If
water level drops no more than 1" (25 mm) after 5 minutes,
evaporative line is in good condition.

CHECK & CUT VALVE

1) Remove check and cut valve from lines. Connect a pressure
gauge with "T" on nipple leading to fuel tank. Hold finger over
opposite nipple.
2) Blow through open end of "T" fitting. When pressure gauge
reads .78-1.0 psi (.06-.07 kg/cm

), valve should open.

3) Remove "T" fitting and gauge from fuel tank nipple and
connect to nipple at bottom of valve (atmosphere vent). Valve should
be located horizontally.
4) Repeat test. Valve should open when pressure gauge reads
.14-.71 psi (.01-.05 kg/cm

). If valve does not operate as

described, replace check and cut valve.

FUEL EVAPORATION SYSTEM

Article Text (p. 3)

1983 Mazda RX7

For www.iluvmyrx7.com

Sunday, August 26, 2001 04:58PM

AIR VENT SOLENOID VALVE

Check air vent hose for cracks or damage. Disconnect air
vent hose from ventilation pipe. Slowly blow through hose. Air should
pass through solenoid. Turn ignition "ON" and blow through hose
again. Air should not pass through valve. If valve does not operate
as described, replace valve.

MAINTENANCE

Check system function every 15,000 miles. Check and Cut
Valve should be tested every 25,000 miles. Replace parts as necessary.

END OF ARTICLE

FUEL PUMP - ELECTRIC

Article Text

1983 Mazda RX7

For www.iluvmyrx7.com

Sunday, August 26, 2001 05:54PM

ARTICLE BEGINNING

1983 Electric Fuel Pump
MAZDA

RX7, Pickup

DESCRIPTION & OPERATION

Electric fuel pump is mounted near fuel tank on frame member.
Power is supplied when ignition switch is in the "RUN" position. This
circuit is protected by a 15-amp fuse (20-amp on RX7) at fuse panel.
In-line fuel filter must be changed within recommended mileage
interval before performing tests. If in doubt, install new filter.

TESTING

PRESSURE TEST

1) Remove air cleaner assembly and disconnect fuel line at
carburetor. Connect pressure gauge with restrictor and a flexible
hose. See Fig. 1. Turn ignition on and briefly vent the system into
container by opening hose restrictor.
2) Pressure should stabilize at 2.8-3.6 psi (.19-.25
kg/cm

). If not within specifications, and lines and filter are in

satisfactory condition, replace pump.

Fig. 1: Fuel Pump Pressure and Volume Test

VOLUME TEST

With fuel pressure within limits, open restrictor for one
minute and measure fuel expelled. If not within specifications, check
for restrictions in tank, line or filter. Replace pump if required.

FUEL PUMP VOLUME

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Volume
Application Qt./Min. (cc/Min.)

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