Loss of power, idles slow and rough

Hi,

Is the check engine light staying on when the engine is running? I ask because if it is, we need to retrieve the diagnostic trouble codes stored in the system. Most parts stores will do it for free. That would point us in the right directions.

Otherwise, we need to start checking one component at a time. A rough idle, loss of power, and stalling can be several things. What you indicated could be the issue, fuel pressure. What I can do is this. I will provide links specific to checking for fuel pressure, power loss (which can be related to a partially plugged catalytic converter), and stalling.

Take a look through these and let me know if they help. I will also include a quick video showing how to use a scanner.

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https://www.2carpros.com/articles/stall-at-idle

https://www.2carpros.com/articles/bad-catalytic-converter-symptoms

https://www.2carpros.com/articles/how-to-test-a-catalytic-converter

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

https://youtu.be/YV3TRZwer8k
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Here are the directions and specifications for testing fuel pressure specific to your vehicle. The attached pics correlate with the directions.

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1996 Nissan-Datsun Maxima V6-2968cc 3.0L DOHC MFI (VQ30DE)
Fuel Pressure Test
Vehicle Powertrain Management Fuel Delivery and Air Induction Fuel Pump Fuel Pressure Testing and Inspection Component Tests and General Diagnostics Fuel Pressure Test
FUEL PRESSURE TEST
NOTE:
- When reconnecting fuel line, always use new clamps.
- Make sure that clamp screw does not contact adjacent parts.
- Use a torque driver to tighten clamps.
- Use Pressure Gauge to check fuel pressure.

PROCEDURE
1. Release fuel pressure to zero.
2. Disconnect fuel hose between fuel filter and fuel tube (engine side).

pic 1

3. Install pressure gauge between fuel filter and fuel tube.
4. Start engine and check for fuel leakage.
5. Read the indication of fuel pressure gauge.

At idling:
Approximately 235 kPa (2.4 kg/cm2, 34 psi)
A few seconds after ignition switch is turned OFF to
ON:
Approximately 294 kPa (3.0 kg/cm2, 43 psi)

6. Stop engine and disconnect fuel pressure regulator vacuum hose from intake manifold.
7. Plug intake manifold with a rubber cap.
8. Connect variable vacuum source to fuel pressure regulator.

Vacuum/fuel Pressure Test

pic 2

9. Start engine and read indication of fuel pressure gauge as vacuum is changed.
Fuel pressure should decrease as vacuum increases. If results are unsatisfactory, replace fuel pressure regulator.

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Let me know what you find or if you have other questions.

Take care,
Joe

If it is affected when the fuel level is at a specific point, I have a feeling it has something to do with either the fuel pump itself, or there is a sock like filter that may be plugged toward the bottom.

Now, since the check engine light was on, I would recommend scanning the computer to see if there are codes still stored. That may point us in a different direction. However, I feel it is fuel related.

I would suggest confirming the fuel pressure is within spec and replace the fuel filter if it has has been a long time since it was done.

Here is a link that explains in general how to replace a fuel filter. I attached a pic specific to your vehicle for location.

Let me know if I can help.

Joe