How JustAnswer Works:
  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site.
    Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.
Ask Tim's Auto Repair Your Own Question
Tim's Auto Repair
Tim's Auto Repair, mechanic
Category: Chevy
Satisfied Customers: 15926
Experience:  Have owned a repair shop for 25 yrs.
Type Your Chevy Question Here...
Tim's Auto Repair is online now
A new question is answered every 9 seconds

1998 chevy: 10 ZR2 4.3 liter engine 4x4..wont start..fuel pump

Resolved Question:

I have a 1998 chevy s-10 ZR2 4.3 liter engine 4x4. It won't start, it turns over but won't catch, every once in awhile it does it and now finally it wont' start, it's not the fuel pump just replaced it in the summer and it still runs. This happened in the summer, my uncle replaced the fuel pump thinking it was the fuel pump and it wasn't then he replaced the spider fuel injectors on top the motor that seemed to fix the problem, till now. Also for about a year or so it surges from time to time kinda like how it runs if you have water in the gas. I was thinking maybe the rotor or the distributor cap.
Submitted: 7 years ago.
Category: Chevy
Expert:  Tim's Auto Repair replied 7 years ago.


the first thing you need to do is check the fuel pressure,these must have no less then 60psi at all times,even while the engine is cold and turning the engine....i would think that the pressure will be low,,these wont even start with as much as is very common to get a bad new do check the pressure....then you may want to move on to the tune plugs,wires,rotor,and cap.


please ACCEPT my answer so I can get credit for my work.i don't receive commission unless you do ..I'm not always going to be giving you good news,so please don't let this stand in the way of you accepting my does not cost you more money.we will still be able to communicate.. Bonuses and positive feedback are appreciated!if you are not satisfied with my answer,please do not leave bad feed back,i will gladly opt out and let another expert handle the question.PLEASE ASK IF YOU NEED MORE HELP


fuel pressure

Testing and Inspection

When you turn ON the ignition, the vehicle control module Vehicle Control Module (VCM) energizes the fuel pump relay which powers the fuel pump ON. The pump remains ON as long as the engine is cranking or running and the VCM receives reference pulses. If there are no reference pulses, the VCM shuts the fuel pump OFF within 2 seconds after the ignition was switched to the ON position or if the engine stops. The VCM also turns ON the fuel pump for 2 seconds when you turn OFF the ignition.

An electric fuel pump pumps the fuel through an in-line filter to the fuel meter body assembly. The pump attach's to the fuel level sender assembly inside of the fuel tank. The fuel pump provides fuel pressure above what is needed by the fuel injectors. The pressure regulator keeps the fuel available to the injectors at a regulated pressure. Unused fuel returns to the fuel tank by the fuel return pipe.

Diagnostic Chart (Part 1 Of 5)
Diagnostic Chart (Part 2 Of 5)
Diagnostic Chart (Part 3 Of 5)
Diagnostic Chart (Part 4 Of 5)
Diagnostic Chart (Part 5 Of 5)

The numbers below refer to the step numbers on the diagnostic table.


  1. When the ignition is ON and the fuel pump is running, the fuel pressure indicated by the fuel pressure gauge should read 414-455 kPa (60-66 psi ). The spring pressure inside the fuel pressure regulator controls the fuel pressure.
  2. A fuel system that drops more than 34 kPa (5 psi ) in 10 minutes has a leak in one or more of the following areas:
    • The fuel pump check valve
    • The fuel pump flex pipe
    • The valve or valve seat within the fuel pressure regulator
    • The fuel injectors
    • A fuel pipe
  1. A fuel system that drops more than 14 kPa (2 psi ) in 10 minutes after being relieved to 69 kPa (10 psi ) indicates a leaking fuel pump check valve.
  2. Fuel pressure that drops-off during acceleration, cruise or hard cornering may cause a lean condition. A lean condition can cause a loss of power, surging, or misfire. You can diagnose a lean condition using a scan tool. If an extremely lean condition occurs, the heated oxygen sensors will stop toggling. The heated oxygen sensor output voltages will drop below 300 mV . The fuel injector pulse width will increase. IMPORTANT: Make sure the fuel system is not operating in the Fuel Cut-Off Mode. This can cause false indications by the scan tool.
  3. When you open the throttle quickly, the manifold pressure increases (low vacuum). The fuel pressure regulator increases the fuel pressure as the engine vacuum drops in order to compensate for engine load.
  1. A rich condition may result from the fuel pressure being above 455 kPa (66 psi ). A rich condition may cause a DTC to set. Driveability conditions associated with rich conditions can include hard starting followed by black smoke and a strong sulfur smell in the exhaust.
  2. This test determines if the high fuel pressure is due to a restricted fuel return pipe or if the high fuel pressure is due to a faulty fuel pressure regulator.
  1. A lean condition may result from the fuel pressure being below 414 kPa (60 psi ). A lean condition may cause a DTC to set. Driveability conditions associated with lean conditions can include hard starting (when the engine is cold), hesitation, poor driveability, lack of power, surging, and misfiring. NOTE : Do not. allow the fuel pressure to exceed 517 kPa (75 psi ). Excessive pressure may damage the fuel pressure regulator.
  2. Restricting the fuel return pipe with the fuel pipe shut-off adapter causes the fuel pressure to rise above the regulated fuel pressure. Using a scan tool to pressurize the fuel system, the fuel pressure should rise above 455 kPa (66 psi ) as the valve on the fuel pipe shut-off adapter connected to the fuel return pipe becomes partially closed.
  1. If the injectors are not grounded, check the spark plug associated with a particular fuel injector for fouling or saturation in order to determine if that particular fuel injector is leaking. If checking the spark plug associated with a particular fuel injector for fouling or saturation does not determine that a particular fuel injector is leaking, use the following procedure:
  1. Remove the fuel meter body assembly. Refer to Fuel Meter Body Assembly Replacement
  2. Reinstall the engine compartment fuel feed and return pipes to the fuel meter body and the chassis fuel pipes. Refer to Fuel Hose/Pipes Replacement (Engine Compartment).
  3. Lift the fuel meter body assembly just enough to leave the fuel injector poppet nozzles in the ports.
  4. Pressurize the fuel system by using the scan tool fuel pump enable.
Tim's Auto Repair and 2 other Chevy Specialists are ready to help you