Fuel Injection System
8.15
Symptom Possible Problem Corrective Action
Engine Surges / Runs Rough Fuel System Use clean, fresh fuel. Check for
water in the fuel system.
Verify operation of the fuel pump.
Use diagnostic software to check
fuel pump circuit.
Check fuel pump pressure.
Check for kinked fuel lines.
Erratic EMM operation. RFI from
coils could be causing problem.
Check for codes: 51, 52, and 53.
Check for codes: 81, 82, and 83.
Check CPS resistance.
Fuel Injectors Use diagnostic software to check
fuel injector circuits.
Use timing light to verify opera-
tion.
Verify that each injector is receiv-
ing 39--45VDC when engine is
running.
Verify that injectors are approxi-
mately the same temperature to
the touch. A “hot” injector is a
sign of a grounded internal EMM
connection.
Check each spark plug. Plug
should be a light brown. Coloring
should only be present on 1/2 of
the insulator .
As a test only, swap a known
good injector with the suspect in-
jector.
Verify that injectors are securely
fastened to the cylinders.
Verify that the fuel lines are cor-
rectly installed.
Verify that EMM is not in S.L.O.W.
mode.
Ignition System Verify that correct spark plugs are
installed.
Verify spark plug gap and that in-
sulators are not cracked or loose.
Verify that ALL connections are
clean and tight.
Check ignition coil primary and
secondary resistances.
Check CPS resistance.
Check all pins and wires.
Check for codes: 81, 82, and 83.
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