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View Full Version : No-Crank:No-Start:Fuel System Diagnosis



88Accord-DX
03-31-2005, 11:29 PM
If the starter fails to crank the engine, the problem may range from a faulty starter motor to broken components inside the engine. If no sounds come from the starter motor when it is activated, first disable the ignition system. Then attempt to rotate the crankshaft pulley by hand in the normal direction of rotation. If the crankshaft can be rotated freely through 2 complete revolutions, the starter is probably defective.
If your unable to rotate the crankshaft by hand, the engine my be hydrostatically locked or have broken internal componants. To check for hydrostatic lock, remove all the spark plugs and attempt to rotate the crankshaft again. If oil or coolant squirts from the spark plug holes, this indicates a bad head gasket, warped cylinder head or block, or a cracked cylinder head or block.
If the crankshaft cannot be rotated with all the spark plugs removed, or at least through one complete revolution, the engine may be seized or have broken internal parts. Pull the dipstick and check crankcase oil level. If oil does not register on the dipstick, it is likely that the pistons are seized in their bores or the connecting rods are seized to the crankshaft. If the oil level is sufficient, a broken component may have lodged between moving parts inside the cylinder block, preventing the parts from rotating.
Many overhead camshaft (OHC) engines are non-freewheeling or "interface" engines. On these engines, a no-crank condition may be caused by piston-to-valve contact. This is common occurance when a timing belt slips or breaks, but it may also occur on engines fitted with a timimg chain & spockets. On many belt-driven OHC engines it is possible to easily loosen or remove part of the timing belt cover. Do this, if possible, and check for obvious signs of belt failure.
If the starter cranks the engine but it will not start (or takes a long time to start), confirm that the valve train is operating properly before attempting to crank again. If the timing belt or chain is broken or has jumped, additional cranking may cause severe damage.
A no-start or hard starting can be caused by a faulty ignition, fuel, or emissions control system. It can be caused by a broken or slipped valve train components, especially on free-wheeling engines. A broken timing device may cause some cylinders to have good compression while others have none. A slipped timing device may result in all cylinders having low compression. To determine if the belt or chain is functioning properly, rotate the crankshaft by hand while observing the distributor rotor or camshaft. If these components fail to rotate with crankshaft, the timing belt is broken. If they do rotate with the crankshaft, confirm proper indexing of the rotor or camshaft to determine if the belt or chain has slipped. Rotate the crankshaft until the piston in cylinder #1 is at TDC on the compression stroke. Then check distributor rotor or camshaft position to make sure it is correct.
If the engine mechanical system is okay, check the ignition system, First, reconnect or install any components used to disable the system previously. Then disconnect one of the spark plug wires and install a spark testing tool. (anything to jump arc) Crank the engine and verify that a strong spark occurs. If no spark occurs, begin ignition diagnosis.
Check the fuel system next. On carbureted engines, remove the air cleaner and inspect the carb. venturi area while operating the throttle linkage. When the throttle is opened quickly, a stream(s) of liquid gasoline should spray from the accelerator pump nozzle(s) into the venturi area. If this does not occur, the accelerator pump circuit is faulty or the carburtor bowl is not retreiving fuel. Proceed with the fuel system diagnosis.
Fuel injected engines usually receive high-pressure fuel from an electric pump. To verify that the fuel pump is operating and fuel is reaching the engine, locate the fuel line that supplies fuel to the throttle body or fuel injector rail. Carefully disconnect the fuel line (place shop rag on it) and install an in-line fuel guage. Crank the engine to verify that the guage registers adequate pressure. If the guage does not register any pressure or is very low, proceed with fuel system diagnosis. If fuel pressure is adequate, begin diagnosis of the fuel injection control system.

88Accord-DX
06-11-2005, 08:44 AM
A.S.E. information posted in this thread in case you find it in a search.

frankie89
06-11-2005, 04:17 PM
good info i saved it to my comp.....