Cranks no start

Tiny
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  • 2010 INFINITI G37
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 193,000 MILES
Have one that cranks but no start, I checked the fuel pump fuse and it's good, if there is a relay where is it? I pulled one plug and it is dry. This is a sedan.
Tuesday, January 19th, 2021 AT 12:28 PM

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Tiny
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There is a relay for the fuel pump. It is in the IPDM but I don't think it is serviceable. I attached below the wiring diagram and the testing for the fuel pump for this vehicle.

Also, we can check fuel pressure to confirm this is the issue but it sounds like it is.

https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator

See below for this info and let us know what you find.
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Wednesday, January 20th, 2021 AT 5:53 PM
Tiny
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Can you tell me where the fuel pressure port is? Can't seem to find it.
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Wednesday, January 20th, 2021 AT 6:51 PM
Tiny
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I removed the cover over the pump and I can hear it work whenever I turn the ignition on.
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-1
Wednesday, January 20th, 2021 AT 6:54 PM
Tiny
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Can't tell from the diagram what color wire should have power once ignition is on, it's confusing.
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Wednesday, January 20th, 2021 AT 6:59 PM
Tiny
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The control wire to the relay from the PCM is red. The power supply is yellow from the relay to the pump.

I attached the process on how to test the fuel pressure. Even more reason we need the pressure because if you can hear the pump then the wiring is fine but we need to know if the pump can produce the pressure.
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Wednesday, January 20th, 2021 AT 7:09 PM
Tiny
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I see, now it's more clear, ugh even japanese cars now need special kits or adapters. I will get it ASAP. It's a kit they use to test the pressure as these cars have no port.
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Wednesday, January 20th, 2021 AT 7:18 PM
Tiny
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Haha. Not sure why they all seem to make it harder to test this stuff. Thanks for the update. Let us know what happens. Thanks
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Wednesday, January 20th, 2021 AT 7:37 PM
Tiny
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Still waiting on an adapter to test the fuel pressure, but I sprayed some fuel in the throttle and it started for a second so now we know it's a fuel issue. I am hoping it's the fuel pump, as this is an easy replacement, I read others had an issue with the relay and replaced the IPDM, but I am not sure if it is just the small box by the big fuse box or if it's the whole fuse box, crossing fingers. If the pump is making noise, isn't that an indication that it's getting power from the relay? But test light not showing any light at all at any of the pump wires, unless the test light isn't connected right, I will check again.
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Friday, January 22nd, 2021 AT 3:32 PM
Tiny
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You nailed it. If the pump is making noise then it is a safe assumption that the electrical side is just fine. I would go with the pump as well if it starts on starter fluid.

I attached that process from the manual below.
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Friday, January 22nd, 2021 AT 7:16 PM
Tiny
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There are two u its on this car one behind passenger one behind driver, the one behind the passenger is the fuel pump and I assume the one behind the driver is the fuel sending unit? The directions talk about disconnecting the sending u it from pump, I can't tell from the picture but correct me if am wrong, there is a hose that runs from driver to passenger side pump and that hose needs to be disconnected when I lift up the pump?
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Friday, January 22nd, 2021 AT 7:44 PM
Tiny
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Yes. You are correct. Take a look at the highlighted sections from the attachments below.

When you pull up the main unit there is a fuel line that is highlighted and you release that with the tabs. Then the main unit should come out.

Hopefully this helps but I think you are on it.
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Saturday, January 23rd, 2021 AT 5:14 PM
Tiny
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Yup, exactly, just making sure. Thanks
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Saturday, January 23rd, 2021 AT 5:33 PM
Tiny
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I had a replacement IPDM just in case, as it's a cheap one, same results. Measured fuel pressure and it's great at 50, plenty of fuel comes of the line too. It wants to start. Checked plugs just in case they were fouled/flooded, they looked dark as expected but none are wet, replaced them anyways as am preparing this car for a relative so mind as well. Battery shows 12 after I tickled charged it, but when you start it under load it drops to 5 or 6, so am charging it again, but even with a jumper box it still turns but doesn't start. Am starting to think it's. Spark issue. What controls the spark on these cars?
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Saturday, January 30th, 2021 AT 1:10 PM
Tiny
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Checked on soaked plug again and it is a bit wet so there is fuel, placed a spark plug to ground and there is no spark. Is it safe to say that the ECU is bad? If it was the crankshaft sensor it would not have had any fuel. No codes whatsoever.
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Saturday, January 30th, 2021 AT 3:27 PM
Tiny
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Okay. That is good. Yes. It could be the ECM but that just sends the signal to the coil on when to fire the plugs so it could still be sending the signal but the coil is faulty.

I attached the process on how to test the ignition system but the idea is to go back through the system from the plug and find where you do have power. If you get to the coil and do not have power coming in then we can assume the ECM is the issue.
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Saturday, January 30th, 2021 AT 5:21 PM
Tiny
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Thanks for the info. Hard to believe that all the coils are bad, I will check power at coils and see if I find anything. Which of the coil wires should have constant power when ignition is on and which lights up when starting
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Saturday, January 30th, 2021 AT 5:51 PM
Tiny
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There is power on one of the wires when ignition is on, there is also ground, the 3rd one has no power when starting the car. So I assume no signal is coming from the ECU.
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Saturday, January 30th, 2021 AT 6:23 PM
Tiny
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Great job. I attached the diagram below. Assuming it is the wire in pin 1 from the ECM which should be fired when that coil is to be fired, then I would agree the ECM is faulty.

It is odd that all the coil drivers on the ECM have failed so just make sure the theft light or something silly like that is not on.
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Sunday, January 31st, 2021 AT 4:27 PM
Tiny
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Yes, first thing I checked for is the alarm light but I cannot see it flashing anywhere. Also what is the job of the condenser? I read anoit it few times.
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Sunday, January 31st, 2021 AT 4:40 PM
Tiny
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The condenser is what supplies the low side voltage. So it supplies the 12 volts and then the ECM sends the signal for when the coil is to fire the plug so the coil interrupts the 12 volt feed to create the high voltage spike which gets delivered to the plug.
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Sunday, January 31st, 2021 AT 7:16 PM

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