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Failures in the L-Jetronics fuel injection system can be categorized into five major
categories. The components associated with the potential failures are identified
and measurements are provided which will allow the verification of each
component’s operating condition. Please refer to the system diagrams provided
in section 7.0 to assist in isolating the problem area.
FAILURE CATEGORIES
• Engine does not start • Acceleration not smooth
• Engine misses • Rough idle
• Engine starts and dies
ENGINE DOES NOT START
Possible Problem Procedure
1. Check the fuel pressure by connecting a pressure
gauge with an adapter to the tee found on the driver’s
side of the fuel rail.
2. Disconnect the vacuum hose between the air
distributor and pressure regulator.
3. Turn ignition switch to the on position and open the
air flow sensor valve slightly to start the fuel pump.
4. Fuel pressure should read 35 +/- 1.4 psi with vacuum
hose disconnected. If reading is not correct, proceed
with step 5.
5. Turn the ignition switch to the start position and listen
for the fuel pump. If pump can be heard, then check for
blockage in the fuel filter and fuel line. If pump does not
operate or cannot hear the pump, then verify fuel filter is
good and proceed with step 6.
6. Unscrew the dual relay set and measure for 12 volts
at pin 88d while cranking the engine. If voltage is not
present, proceed with step 7. If voltage is present, then
verify the continuity between pin 88d and the fuel pump,
or verify voltage is present at the fuel pump.
7. Verify that 12 volts is present on the double relay at
relay terminals 88y at all times and at 86a while
cranking the engine. If voltage is not present at 86a
while cranking the engine, then go to stop 9.
8. If voltage is not present at 88y, then check for
continuity between regulator, one side of the fuses (S23,
S24) in the rear relay panel and then to pin 88y on the
dual relay. If voltage is present at 88y, go to step 9.
Fuel Pressure or
Fuel Pump
9. Verify continuity between pin 50 of the ignition switch
and pin 88a of the dual relay. If continuity is good, then
the ignition switch may be bad.