Engine Controls - Basic Engine Testing - 5.2l Cng Dodge Ram Wagon B1500

INTRODUCTION

The following diagnostic steps will help prevent overlooking a simple problem. This is also where to begin diagnosis for a no-start condition.

The first step in diagnosing any driveability problem is verifying the customer's complaint with a test drive under the conditions the problem reportedly occurred.

Before entering self-diagnostics, perform a careful and complete visual inspection. Most engine control problems result from mechanical breakdowns, poor electrical connections or damaged/misrouted vacuum hoses. Before condemning the computerized system, perform each test listed in this article.

Note. Perform all voltage tests with a Digital Volt-Ohmmeter (DVOM) with a minimum 10-megohm input impedance, unless stated otherwise in test procedure.

VISUAL INSPECTION

Visually inspect all electrical wiring, looking for chafed, stretched, cut or pinched wiring. Ensure electrical connectors fit tightly and are not corroded. Ensure vacuum hoses are properly routed and are not pinched or cut. Inspect air induction system for possible vacuum leaks.

Compression

Check engine mechanical condition with a compression gauge, vacuum gauge, or an engine analyzer. See engine analyzer manual for specific instructions.

COMPRESSION SPECIFICATIONS

FUEL PRESSURE RELEASE

Scheme 142

1. Ensure all fuel cylinder valves located at end of each fuel cylinder is in CLOSED position by rotating knob on fuel cylinder valve fully clockwise. There are 2 fuel cylinders located transversely behind rear axle and one fuel cylinder on inside of driver's side frame rail, in front of rear wheel. There may be an optional fuel cylinder located on inside of passenger's side frame rail, in front of rear wheel. Number of fuel cylinders may vary with vehicle application.
2. Note location of manual fuel shutoff valve, located on inside of passenger's side frame rail, just in front of passenger's side rear wheelwell. (Scheme 142)
3. Ensure manual fuel shutoff valve is in OPEN position with valve handle in-line (parallel) with the fuel line. If valve handle is at 90-degree angle to the fuel line, manual fuel shutoff valve is in CLOSED position.
4. If engine is operable, go to next step. If engine is inoperable, go to step 6).
5. Start engine and allow to idle until engine stalls. Attempt to start engine 3 more times. Ensure engine will not run. Go to step 9).
6. If engine is inoperable, move vehicle outside. Cycle ignition on and off several times to activate high pressure fuel shutoff solenoid. Ensure ignition is off.
7. Slowly loosen fuel line nut at fuel shutoff solenoid, located near center of driver's side fuel rail. (Scheme 143) Leave fuel line nut loose until all fuel pressure is released.
8. Once fuel pressure is released, tighten fuel line nut at fuel shutoff solenoid to 20 ft. lbs. (27 N.m). Go to next step.
9. On all applications, fuel pressure in fuel lines should now be released. Use care when disconnecting fuel lines, as some fuel pressure may still exist in fuel lines.

Scheme 143

Fuel Cylinder Pressure Release

1. On fuel cylinders NOT being serviced, ensure fuel cylinder valve located at end of each fuel cylinder is in CLOSED position by rotating knob on fuel cylinder valve fully clockwise.
2. Ensure fuel cylinder valve is in OPEN position on fuel cylinder being serviced by rotating knob on fuel cylinder valve fully counterclockwise. There are 2 fuel cylinders located transversely behind rear axle and one fuel cylinder on inside of driver's side frame rail, in front of rear wheel. There may be an optional fuel cylinder located on inside of passenger's side frame rail, in front of rear wheel. Number of fuel cylinders may vary with vehicle application.
3. If engine is operable, go to next step. If engine is inoperable, go to step 6).
4. Note location of manual fuel shutoff valve, located on inside of passenger's side frame rail, just in front of passenger's side rear wheelwell. (Scheme 142) Ensure manual fuel shutoff valve is in OPEN position with valve handle in-line (parallel) with the fuel line. If valve handle is at 90-degree angle to the fuel line, manual fuel shutoff valve is in CLOSED position.
5. Start engine and allow to idle until engine stalls. Attempt to start engine 3 more times. Ensure engine will not run. Go to step 7).
6. If engine is inoperable, move vehicle outside. Slowly loosen fuel line fitting at fuel cylinder valve on fuel cylinder being serviced to release fuel pressure. Leave fuel tube fitting loosen until fuel pressure is released. Go to next step.
7. On all applications, once all fuel pressure is released, fuel cylinder may be serviced. Rotate knob on fuel cylinder valve for fuel cylinder being serviced fully clockwise to CLOSED position.

FUEL PRESSURE

1. Ensure fuel cylinder(s) are at least 1/2 full before checking fuel pressure. Remove engine cover. Remove air cleaner assembly.
2. Connect (0-300 psi) fuel pressure gauge to fuel pressure test port, located at rear corner of driver's side fuel rail. (Scheme 143)
3. Start engine and note fuel pressure. Minimum operating fuel pressure is 90 psi (6.3 kg/cm 2 ), and maximum operating fuel pressure is 140 psi (9.8 kg/cm 2 ). Fuel pressure may be affected by following conditions: Regulated Fuel Cylinder Pressure Engine Temperature Outside Ambient Temperature Low Pressure Fuel Shutoff Solenoid Condition Fuel Injector Condition High Pressure Fuel Shutoff Solenoid Condition High Pressure Fuel Shutoff Solenoid Relay Condition Engine Load Requirements
4. If fuel pressure exceeds 140 psi (9.8 kg/cm 2 ) with engine at normal operating temperature, replace fuel pressure regulator. See the «REMOVE/INSTALL/OVERHAUL - 5.2L (CNG)»(/dodge/ram-wagon-b1500/1996-1997/remont/removal-installation/#how-to-overhaul-installation-52l-cng-the-engine-controls-removal) article.
5. If fuel pressure is less than 90 psi (6.3 kg/cm 2 ), ensure fuel cylinders contain adequate amount of fuel. Ensure manual fuel shutoff valve is in OPEN position with valve handle in-line (parallel) with the fuel line. If valve handle is at 90-degree angle to the fuel line, manual fuel shutoff valve is in CLOSED position.
6. Manual fuel shutoff valve is located on inside of passenger's side frame rail, just in front of passenger's side rear wheelwell. (Scheme 142)
7. On all models, if manual fuel shutoff valve is in OPEN position, ensure all fuel cylinder valve(s) on fuel cylinder(s) are open by rotating fuel cylinder valve knob fully counterclockwise. Fuel cylinder valve is located at end of each fuel cylinder.
8. There are 2 fuel cylinders located transversely behind rear axle, with one fuel cylinder on inside of driver's side frame rail, in front of rear wheel. There may be an optional fuel cylinder located on inside of passenger's side frame rail, in front of rear wheel. Number of fuel cylinders may vary with vehicle application.
9. On all models, if all fuel cylinder valves are in fully OPEN position, inspect fuel lines for kinks and restrictions. If fuel lines are okay, go to next step.
10. Check and high pressure fuel shutoff solenoids. See «SYSTEM/COMPONENT TESTS - 5.2L (CNG)»(/dodge/ram-wagon-b1500/1996-1997/remont/testing-diagnostics/#engine-system-testing-engine-component-testing-52l-cng) article.
11. If and high pressure fuel shutoff solenoids are okay, it may be necessary to check the electronic control system and relays for and high pressure fuel shutoff solenoids, as solenoids are controlled by the PCM. See «TESTS W/CODES - 5.2L»(/dodge/ram-wagon-b1500/1996-1997/remont/testing-diagnostics/#engine-controls-tests-wcodes-52l) article.
12. If and high pressure fuel shutoff solenoids and operating circuits are operating correctly, check fuel injectors. See «SYSTEM/COMPONENT TESTS - 5.2L (CNG)»(/dodge/ram-wagon-b1500/1996-1997/remont/testing-diagnostics/#engine-system-testing-engine-component-testing-52l-cng) article.
13. Remove fuel pressure gauge. Inspect fuel system for leaks. See «FUEL SYSTEM LEAK TESTING»(/dodge/ram-wagon-b1500/1996-1997/remont/testing-diagnostics/#engine-controls-basic-engine-testing-52l-cng__fuel-system-leak-testing) under FUEL SYSTEM. Reinstall necessary equipment.

FUEL SYSTEM LEAK TESTING

Note. Each fuel cylinder must be removed and inspected every 3 years in accordance with American National Standard ANSI/AGA NGV2 (USA applications) or Canadian Standards Association (Canada applications). Inspection must be performed by an qualified individual. Retest marking must be placed on neck of fuel cylinder, or on tag attached to fuel cylinder. Fuel cylinder expires and must be replaced after being in service for 15 years from fuel cylinder manufacturing date, stamped on tag attached to fuel cylinder. A label should be installed on inside of fuel filler door and indicates fuel cylinder retest date and expiration date.

1. If a fuel system leak is suspected, fuel system may be inspected for leaks using a commercially available liquid leak detector. Ensure fuel system is under operating pressure when performing fuel system leak test.
2. Apply generous amount of leak detector fluid to suspected leak area. Monitor area for 3-5 minutes. If steady flow of bubbles exists, leak exists.
3. If fuel system leak exists, repair fuel system leak as necessary. For servicing of fuel lines and fittings, see «REMOVE/INSTALL/OVERHAUL - 5.2L (CNG)»(/dodge/ram-wagon-b1500/1996-1997/remont/removal-installation/#how-to-overhaul-installation-52l-cng-the-engine-controls-removal) article.

IGNITION CHECKS

Note. For ignition system spark testing and component testing, see appropriate NO TROUBLE CODE (NTC) TEST and NO START (NS) TEST in TESTS W/CODES - 5.2L article.

NO-START TESTING PROCEDURES

For additional information on no-start testing procedures, see NO START (NS) tests in TESTS W/CODES - 5.2L article.

IDLE SPEED & IGNITION TIMING

Ensure idle speed and ignition timing are set to specification. For adjustment procedures, see ADJUSTMENTS - 5.2L article.

SUMMARY

If no faults were found while performing BASIC DIAGNOSTIC PROCEDURES, go to the TESTS W/CODES - 5.2L article. If no Diagnostic Trouble Codes (DTCs) are found in self-diagnostics, go to the TESTS W/O CODES - 5.2L (CNG) article for diagnosis by symptom (i.e., ROUGH IDLE, NO-START, etc.) or intermittent diagnostic procedures.

See also:
• REMOVE/INSTALL/OVERHAUL - 5.2L (CNG)
• SYSTEM/COMPONENT TESTS - 5.2L (CNG)
• TESTS W/CODES - 5.2L
• ADJUSTMENTS - 5.2L
• TESTS W/O CODES - 5.2L (CNG)
• FUEL SYSTEM LEAK TESTING