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Dave Nova
Dave Nova, Pontiac Technician
Category: Pontiac
Satisfied Customers: 18884
Experience:  ASE Master Certification. GM World Class Certification
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Pontiac Sunfire: My son has a 2001 pontiac sunfire. It wont

Customer Question

My son has a 2001 pontiac sunfire. It won't start. The fule pump runs but the car will not fire up. It does not appear to be getting gas to the cylinders. Spark plugs are dry. The fule injectors may not be working? What should I check next?
Submitted: 2 years ago.
Category: Pontiac
Expert:  Dave Nova replied 2 years ago.
Hello and thank you for using JustAnswer. My name is XXXXX XXXXX I will do my best to help you with your Pontiac problem.

If you have a test light, you can check for electrical pulse to injectors. Disconnect one of the injectors and connect the test light across the two terminals of the injector connector and crank the engine. The test light should flash while cranking the engine. Let me know what you find there.
Customer: replied 2 years ago.

Dave

 

This is a dumb question but, can you tell me where the injectors are located so I can check them.

Expert:  Dave Nova replied 2 years ago.
graphic

graphic
Customer: replied 2 years ago.
the answer is no , the test light does not light up. no power to the injectors
Expert:  Dave Nova replied 2 years ago.
Check the F/P INJ fuse in the dash fuse panel. If this fuse looks good, test for power at the fuse with the key on. Let me know what you find.
Customer: replied 2 years ago.

There is power to the fuse

 

Expert:  Dave Nova replied 2 years ago.
Test for power on gray wire at one of the injector connectors. You should have power for two seconds when the key is turned to ON, you should also have power while cranking the engine. Let me know what you find.
Customer: replied 2 years ago.

I don't see power in either case. The light does not go on

Expert:  Dave Nova replied 2 years ago.
Does the fuel pump run when the key is turned on? Does the fuel pump run when cranking? If not then the fuel pump relay may be bad. This relay supplies power from the fuse you tested to the fuel pump and the four injectors. If the pump runs then there may be a break in the gray wire between the fuel pump relay and the injectors.
Customer: replied 2 years ago.

The fuel pump runs when the key is turned on

 

is there some sort of shut off on the gas as a safty precaution?

 

or is there a shut off on the injectors.

Expert:  Dave Nova replied 2 years ago.
The security system will shut down the injectors, but it shuts down the ground side through the ECM. If you are not getting any power on the gray wire then you have a power supply problem and this has to be a break in the wire between the fuel pump relay and the injectors. Temporarily install a jumper wire from battery positive to the gray wire at the injector harness and try starting the engine. If it starts, this is verification that the gray wire needs to be repaired. Instead of tracking down the break in the wire, you could run a new wire from the injector harness back to the fuel pump relay.
Customer: replied 2 years ago.

I think your right, I just pulled apart the wire harness. Each injector has a separate set of wires running to it. I cut one set of wires and both were dead. (blue and a light gray) Is there any trick to getting the far end of the relay box to detach from the car. End closest to the driver.

 

There is a lot of corrosion on this car. I am going to replace the relay as well just in case, and try the power jumper wire from the battery you spoke of. I will try to tackel this in the morning.

Expert:  Dave Nova replied 2 years ago.
graphic
1. Open the hood.
2. Disconnect the negative battery cable from the battery.
3. Remove the air cleaner mounting bracket.
4. Remove the push-in retainer (3) from the electrical center.
5. Remove the electrical center from the inner fender.
6. Turn the electrical center over and remove the bottom cover.
7. Remove the four plastic wire retainers.

Let me know how things turn out. Remember that I will always provide follow up even after you accept my answer.

Dave Nova, Pontiac Technician
Category: Pontiac
Satisfied Customers: 18884
Experience: ASE Master Certification. GM World Class Certification
Dave Nova and 3 other Pontiac Specialists are ready to help you
Customer: replied 2 years ago.

Dave,

 

Question, if each injector is to push gas in each cylinder at a specific point in the cylinder's rotation then if I run one power cable from the fuel pump relay to all the injectors how will that work.

Expert:  Dave Nova replied 2 years ago.
They all get power from the relay on the gray wire. Each injector gets a separate ground from the PCM. That is why each injector has a different colored wire. This is the individual ground wire that the PCM uses to turn the injectors on and off in the correct order. The gray wire at each injector is already connected together with the others. Connecting one gray wire back to the relay should power up all the others.
Customer: replied 2 years ago.

Hi Dave

 

I have run a new power. I checked it and it does have power when I turn the key on. I connected three of the four injectors to the new power. And still the cylinders will not fire. Any ideas. I also check the fuel pump relay and that is fine.

Expert:  Dave Nova replied 2 years ago.
Connect a test light across from gray to other colored wire at one of the injectors and crank the engine to see if the light flashes.
Customer: replied 2 years ago.

Dave,

 

To my surprise, when you connect the positive to the ground there is a connection and the circuit tester light does go on.

Expert:  Dave Nova replied 2 years ago.
Power will flow through the injector to the other side of the circuit.
Customer: replied 2 years ago.

Dave,

 

So are you saying that the injectors are working? If that is true why is the car not working?

 

 

Expert:  Dave Nova replied 2 years ago.
Did test light flash when cranking the engine with the test light connected across the injector connector terminals?
Customer: replied 2 years ago.

Yes

 

Expert:  Dave Nova replied 2 years ago.
If the light is flashing when cranking then the injectors should be working. If the fuel pump is running and supplying pressurized fuel to the engine, you should now be getting fuel to the cylinders.
Customer: replied 2 years ago.
This problem must be intermittent, and that is probably why I am having such a difficult time tracking it down. This morning the light flashed when I connected the positive to the ground on the fuel injector. Now I am getting nothing. I am still getting a light when I connect the new power to the ground on the battery but nothing when I connect the ground wire on the fuel injector to the new power so the problem has to be with the ground. Where do I trace that back to?
Expert:  Dave Nova replied 2 years ago.
The injector ground wires go back to the PCM. Check the injector harness, all wires should come together into one connector that plugs into the main engine harness. Make sure this connector is plugged in securely.

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