Engine - Prolonged Crank Time After Hot Soak
BULLETIN NUMBER:SB96-02-L002
ISSUE DATE:
MAY 1996
GROUP:
FUEL
1994-95 TROOPER (UX) AND 1994-95.5 RODEO (UC) 6VD1 SOHC ENGINE
PROLONGED CRANKING TIME AFTER HOT SOAK
AFFECTED VEHICLES
1994-95 Trooper (UX) and 1994-95.5 Rodeo (UC) models equipped with 6VD1 SOHC engine.
SERVICE INFORMATION
On some affected vehicles, about a five second cranking time or more is needed to start the engine after the vehicle is exposed to a hot soak (i.e., the engine is shut off for 30 to 90 minutes after running at normal temperature). This prolonged engine cranking time may be caused by the fuel injector leak-down rate.
To eliminate this prolonged engine cranking time, create a hot soak condition, then check the fuel injector leak down rate using the procedure described in this Service Bulletin. If the leak down rate is not within specification, replace all six fuel injectors.
SERVICE PROCEDURE
IMPORTANT!
Before performing this procedure, remove all fuel pressure from the fuel injector rails, using the following steps:
^ Remove fuel pump relay from underhood relay box.
^ Start engine and allow to stall.
^ Crank engine for additional 30 seconds.
^ Turn ignition switch off
MEASUREMENT
Fuel Injector Leak Down Rate
^ Connect Fuel Pressure Gauge J-34730-1, or equivalent, to Schrader valve in fuel injector rail (Figure 1). Reinstall fuel pump relay.
NOTE
Check the appropriate Workshop Manual for the actual location of the Schrader value. To minimize fuel spillage, wrap a shop towel around the Schrader valve. Bleed the air from the fuel pressure gauge hose according to the manufacturer's directions.
^ Pressurize fuel system by turning ignition switch on for approximately five seconds, then off.
IMPORTANT!
Do not crank the engine in the above step.
^ Check fuel pressure reading on fuel pressure gauge after pump stops. Fuel pressure should be between 41-46 psi. If fuel pressure holds steady at 41 psi or more, proceed to next step. If fuel pressure is out of specifications, refer to appropriate Workshop Manual for further testing.
^ Bring engine up to operating temperature by driving vehicle at highway speeds for at least five minutes. Turn ignition switch off and park vehicle for 30 to 90 minutes.
^ Using stopwatch, record engine cranking time. Start watch when cranking begins; stop watch when engine idle begins. If engine began idling within a five second time period, residual pressure loss is OK. If engine took longer than five seconds, proceed with next step.
^ Turn ignition switch off.
^ Gradually block fuel return line by pinching flex hose.
^ Pressurize fuel rail by turning ignition switch on for approximately five seconds, then off.
IMPORTANT!
Do not crank the engine in the above step.
^ Gradually block fuel pressure line by pinching flex hose.
^ With fuel pressure gauge still connected to fuel rail, record fuel pressure reading. Wait 20 minutes, then read fuel pressure gauge. If fuel pressure does not drop more than 20 psi, injector leak down rate is not cause of excessive engine cranking. Refer to appropriate Workshop Manual to diagnose and correct problem. If fuel pressure drops more than 20 psi, proceed with next step.
^ Replace all six (6) fuel injectors in accordance with appropriate Workshop Manual.
NOTE
All technical readings (e.g., fuel pressure, injector leak down rate, etc.) must be recorded on the repair order to support this repair.
Before installing the fuel injectors, be sure to lubricate the O-rings with engine oil.
PARTS INFORMATION
Part Number Description Quantity
Required
8-17105-388-0 Injector & Clip 6
Assembly
(SOHC)
8-94364-577-0 Gasket; 1
Common
Chamber
8-94389-939-0 Gasket; 1
Throttle Body
FLAT RATE MANUAL INFORMATION
Use published Flat Rate Manual labor operation number 0202851).