Nissan Z - ZX 1970-1988 Repair Guide

Evaporative Emissions System

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Check the evaporation control system every 12,000 miles (19,000 km). Check the fuel and vapor lines/hoses for proper connections, routing and condition; replace the damaged or deteriorated parts as necessary.

1970-74 MODELS



See Figure 1

Remove and check the operation of the check valve as follows:

  1. Disconnect the hoses from the valve and apply air pressure to the fuel tank side of the valve; the air should flow through the valve and exit the crankcase side of the valve. If the operation is not correct, replace the valve.
  2.  
  3. Apply air pressure to the crankcase side of the valve; air should not pass to either of the other two outlets.
  4.  



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Fig. Fig. 1: Evaporative emissions system check valve

  1. Apply air pressure to the carburetor side of the valve; the air should exit through the fuel tank and/or the crankcase side of the valve.
  2.  

1975-88 MODELS



See Figures 2 and 3

The flow guide is replaced with a carbon filled canister which stores fuel vapors until the engine is started; vapors are then drawn into the combustion chambers and burned.

To check the operation of the carbon canister purge control valve, proceed as follows:

  1. Disconnect the rubber hose between the canister control valve and the T-fitting at the T-fitting.
  2.  



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Fig. Fig. 2: Component list of canister purge valve



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Fig. Fig. 3: Replacing the canister filter

  1. Apply vacuum to the hose leading to the control valve. The vacuum should be maintained indefinitely.
  2.  

If the control valve leaks, remove the top cover of the valve and check for a dislocated or cracked diaphragm. If the diaphragm is damaged, a repair kit containing a new diaphragm, retainer and spring is available and should be installed.

The carbon canister has an air filter in the bottom of the canister. The filter element should be checked and replaced as indicated on the Maintenance Intervals chart. Replace the filter by removing the canister, pulling the filter out of the bottom of the canister and installing a new filter.

Sealant has been applied to the base of the canister and the canister tray on 1979 and later ZXs. To remove, pull the tray from the canister, while twisting the canister at the same time. Apply sealer to the canister tray before replacement. Note that the filter replacement is not a regularly scheduled emissions service on 1980 and later models. On these vehicles, the filter must be replaced only when it is clogged.

For further information on the Evaporative emissions system, refer to Emissions Controls .

 
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