Fuel, Air Induction, Exhaust Systems Flashcards
A - turning off fuel injectors at high RPM is the purpose of the rev limiter; to protect the engine from damage or limit vehicle speed.
B - turning off fuel injectors while the engine is running must be done at speeds above 45 mph.
A - correct.
B - incorrect.
A vehicle is being diagnosed for a P0134 DTC (oxygen sensor circuit, no activity detected bank 1, sensor 1).
A - the problem could be high fuel system pressure
B - the problem is more likely confined to the downstream oxygen sensor on the bank containing cylinder 1.
A - incorrect. High fuel pressure would affect all cylinders.
B - incorrect. Bank 1, sensor 1 is the upstream sensor on bank 1.
Which of the following is the least likely cause of a fuel tank leak? A - rust B - road damage C - retaining straps D - leaking tank seams
a - likely
b - likely
c - least likely
d - likely
A - special fuel injection hose must be used when replacing the fuel lines on a fuel injected vehicle.
B - the fuel supply hose is usually smaller than the fuel return hose.
A - correct
B - incorrect. The fuel supply hose is usually larger than the return hose.
A - a vehicle with a restricted fuel filter can still have fuel pressure within specifications.
B - if a restricted fuel filter is suspected, then a fuel pump volume test can be performed.
both correct
A restricted filter will affect the volume, not pressure.
A - fuel pressure readings above specifications could be caused by a stuck open fuel pressure regulator.
B - if fuel is present at the vacuum hose port of a fuel pressure regulator, then the regulator is stuck open.
A - incorrect. A stuck open fuel pressure regulator would cause low fuel pressure.
B - incorrect. Fuel in the vacuum hose of a fuel pressure regulator is due to a ruptured diaphragm.
Fuel pressure higher than specifications can be caused by a stuck closed fuel pressure regulator or a restriction in the return line on a return type fuel system.
A - performing a fuel pressure test confirms proper operation of the fuel injector.
B - it is possible to have an electrical problem with an injector, even though the fuel pressure drop is within specifications.
A - incorrect
B - correct
A - a vacuum leak can occur under the intake manifold and cause oil consumption.
B - propane is a good method for locating vacuum leaks.
both correct
A - fuel pressure regulator operation is being tested.
B - as vacuum is applied to the regulator, the fuel pressure should increase.
A - correct.
B - incorrect. As vacuum is applied to the regulator, fuel pressure should decrease.
A - the exhaust can be checked for restrictions using a vacuum gauge.
B - the back pressure in the exhaust should not exceed 1.5 psi at idle.
A - correct.
B - correct. Exhaust back pressure at idle should be < 1.5 psi and < 2.5 psi at 2000 rpm.
