Volkswagen New Beetle. Manual - part 34

VACUUM PUMP DIAGNOSIS 

FUEL INJECTION TROUBLE SHOOTING 

BASIC FUEL INJECTION TROUBLE SHOOTING CHART 

Thermostat stuck closed 

Remove and replace thermostat, see 

ENGINE COOLING 

Head gasket leaking 

Replace head gasket 

Oil Light on at Idle 

Low oil pump pressure 

Check oil pump operation, see 

ENGINES 

Oil cooler or line restricted 

Remove restriction and/or replace 

cooler 

Engine Won't Shut Off 

Injector pump fuel solenoid does not return 
fuel valve to OFF position 

Remove and check solenoid and 

replace if needed 

CONDITION & POSSIBLE CAUSE 

CORRECTION 

Excessive Noise 

Loose pump-to-drive assembly screws 

Tighten screws 

Loose tube on pump assembly 

Tighten tube 

Valves not functioning properly 

Replace valves 

Oil Leakage 

Loose end plug 

Tighten end plug 

Bad seal crimp 

Remove and re-crimp seal 

NOTE:

This is GENERAL information. This article is not intended to be specific to any 
unique situation or individual vehicle configuration. The purpose of this Trouble 
Shooting information is to provide a list of common causes to problem 
symptoms. For model-specific Trouble Shooting, refer to SUBJECT, 
DIAGNOSTIC, or TESTING articles available in the section(s) you are accessing. 

CONDITION & POSSIBLE 
CAUSE 

CORRECTION 

Engine Won't Start (Cranks Normally) 

Cold start valve inoperative 

Test valve and circuit 

Poor connection;vacuum or 
wiring 

Check vacuum and electrical connections 

Contaminated fuel 

Test fuel for water or alcohol 

Defective fuel pump relay or 
circuit 

Test relay and wiring 

Battery too low 

Charge and test battery 

 

1998 Chevrolet Pickup C1500 

GENERAL INFORMATION Trouble Shooting - Basic Procedures

  

Low fuel pressure 

Test pressure regulator and fuel pump, check for 

restricted lines and filters 

No distributor reference 
pulses 

Repair ignition system as necessary 

Open coolant temperature 
sensor circuit 

Test sensor and wiring 

Shorted W.O.T. switch in 
T.P.S. 

Disconnect W.O.T. switch, engine should start 

Defective ECM 

Replace ECM 

Fuel tank residual pressure 
valve leaks 

Test for fuel pressure drop after shut down 

Hard Starting 

Disconnected hot air tube to 
air cleaner 

Reconnect tube and test control valve 

Defective Idle Air Control 
(IAC) valve 

Test valve operation and circuit 

Shorted, open or misadjusted 
T.P.S. 

Test and adjust or replace T.P.S. 

EGR valve open 

Test EGR valve and control circuit 

Poor Oxygen sensor signal 

Test for shorted or circuit 

Incorrect mixture from PCV 
system 

Test PCV for flow, check sealing of oil filter cap 

Poor High Speed Operation 

Low fuel pump volume 

Faulty pump or restricted fuel lines or filters 

Poor MAP sensor signal 

Test MAP sensor, vacuum hose and wiring 

Poor Oxygen sensor signal 

Test for shorted or open sensor or circuit 

Open coolant temperature 
sensor circuit 

Test sensor and wiring 

Faulty ignition operation 

Check wires for cracks or poor con- nections, test 

secondary voltage with oscilloscope 

Contaminated fuel 

Test fuel for water or alcohol 

Intermittent ECM ground 

Test ECM ground connection for resistance 

Restricted air cleaner 

Replace air cleaner 

Restricted exhaust system 

Test for exhaust manifold back pressure 

Poor MAF sensor signal 

Check leakage between sensor and manifold 

Poor VSS signal 

If tester for ALCL hook-up is available check that 

VSS reading matches speedometer 

Ping or Knock on Acceleration 

Poor Knock sensor signal 

Test for shorted or open sensor or circuit 

Poor Baro sensor signal 

Test for shorted or open sensor or circuit 

Improper ignition timing 

See VEHICLE EMISSION CONTROL LABEL 

 

1998 Chevrolet Pickup C1500 

GENERAL INFORMATION Trouble Shooting - Basic Procedures

  

IGNITION SYSTEM TROUBLE SHOOTING 

(where applicable) 

Check for engine overheating 
problems 

Low coolant, loose belts or electric cooling fan 

inoperative 

NOTE:

For additional electronic fuel injection trouble shooting information, see the 
appropriate article in the ENGINE PERFORMANCE section (not all vehicles have 
Computer Engine Control articles). Information is provided there for diagnosing 
fuel system problems on vehicles with electronic fuel injection. 

NOTE:

This is GENERAL information. This article is not intended to be specific to any 
unique situation or individual vehicle configuration. The purpose of this Trouble 
Shooting information is to provide a list of common causes to problem 
symptoms. For model-specific Trouble Shooting, refer to SUBJECT, 
DIAGNOSTIC, or TESTING articles available in the section(s) you are accessing. 

 

1998 Chevrolet Pickup C1500 

GENERAL INFORMATION Trouble Shooting - Basic Procedures

  

Fig. 3: Ignition Secondary Trouble Shooting Chart

 

1998 Chevrolet Pickup C1500 

GENERAL INFORMATION Trouble Shooting - Basic Procedures