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Old 04-15-2017, 05:23 PM   #31
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Re: Engine misses when warmed up.

As per Shoe Box's suggestion,I located the fuel pump prime connector and applied 12v to it, but nothing happened. No fuel pump sound or action to the pressure gauge. What do you think?
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Old 04-15-2017, 06:44 PM   #32
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Re: Engine misses when warmed up.

Only two possibilities at this point:

1 - the pump is dead

2 - there is a problem with the harness conector or the ground wire that runs to the connector

http://shbox.com/1/fuel_pump_wiring.jpg

http://shbox.com/1/fuel_pump_connector.jpg
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Old 04-16-2017, 09:44 PM   #33
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Re: Engine misses when warmed up.

I do not get any current to the fuel pump connector. Can I just ground the ground wire connection at the connector?
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Old 04-17-2017, 10:42 AM   #34
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Re: Engine misses when warmed up.

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Originally Posted by Rod Bender View Post
I do not get any current to the fuel pump connector. Can I just ground the ground wire connection at the connector?
You are not looking for "current". You are looking for "voltage". I'm assuming you are asking about the "connector" for the fuel pump at the rear of the car. You need to determine if you have 12 VOLTS on the pin for the gray wire in the portion of the connector attached to the body. Do not probe the harness side of the connector if it is disconnected from the body side connector.

You will only get 12 VOLTS on that pin under three conditions:

1 - the engine is running, OR

2 - you have 12 VOLTS connected to the fuel pump prime connectors, OR

3 - without anything connected to the prime connector, you measure the voltage within two seconds of turning the key to "run".

When you turn the key to run, the PCM turns on the pump, but if the engine does not start, it turns the pump off after two seconds, and waits until the engine starts to crank before it restarts the pump.

Next, you want to verify that you have a good ground to the part of the connector that is attached to the body. Set your meter to OHMS. Touch the black lead to a good chassis ground, and probe the pin in the body side of the connector for the black wire. Should measure close to 0 OHMS. If it reads "out of range" or a very large number of OHMS, the ground is faulty.
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Old 04-17-2017, 03:31 PM   #35
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Re: Engine misses when warmed up.

If I understand, I should unplug the part of the pump connector in Shoebox's photo that goes to the fuel pump from the part from the front of the car that carries current. Then it is at that point I check for 12v in the grey wire that only lasts for two seconds after the key is turned to run. If I do not have 12v I should check my black wire for ground at that location as you suggested.
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Old 04-17-2017, 07:49 PM   #36
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Re: Engine misses when warmed up.

A circuit needs a 12 volt source and a ground. If either is missing the circuit is incomplete.

First we check for 12 volts. Red meter probe goes into the body side of the plug where the gray wire is positioned. Black wire makes contact with a good chassis ground. If you have 12 volts, you have answered 1/2 of the question. If you don't have 12 volts, you have to trace the gray wire back to its source and find the break.

If you got 12 volts, now we check the ground. To simplify, leave the meter set to D.C. volts, keep the red meter probe in the pin for the gray wire, and place the black probe on the pin where the black wire is positioned. Meter should still indicate 12 volts if the connector ground is good.

If both pins check out, the pump or the wiring inside the tank has failed.

Keep this simple. Start by connecting 12 volts to the prime connector. Make the above test. If you have 12 volts at the gray wire position, you have proved the wire from the fuel pump relay to the body connector is good. Then disconnect the 12 volts at the prime connector, and move on to checking for voltage in the 2-second window. That's not going to be easy. And, you could even check at the relay rather than the rear body connector. But you might have an issue homing in on the correct pin on the relay (which is under the plastic footrest on the left edge of the driver side floor). At least inside the car you could turn the key while observing the meter.
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Old 04-19-2017, 03:24 PM   #37
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Re: Engine misses when warmed up.

It works! Unfortunately not the engine. But I did have my wife turn the key while I held my volt/ohm meter probe to the grey wire as you said. Now, the voltage it read was 11.71. I then checked voltage at the battery and it is 12.38. Is that too much of a drop to engage the fuel pump? Because I did not hear the pump run. Does this now indicate the fuel pump is at fault?
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Old 04-20-2017, 06:39 PM   #38
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Re: Engine misses when warmed up.

So. What is the best way to get the fuel pump out?
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Old 04-20-2017, 07:29 PM   #39
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Re: Engine misses when warmed up.

Two options....

1 - per the factory manual, drop the exhaust, drop the rear axle assembly, drop the tank.

2 - cut an access hatch in the package shelf.

https://www.camaroz28.com/forums/fue...th-gen-619463/
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Old 04-20-2017, 11:30 PM   #40
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Re: Engine misses when warmed up.

Thanks Fred. I read them all. I think I will check my fuel filter.
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