On second start up of the day it shuts off two to three seconds after starting

Hi,

The idea that it turns off and you notice a power loss up hill could be related to a weak fuel pump. Is the check engine light staying on when the engine is running? If it is, I suggest having the computer scanned for diagnostic trouble codes.

This vehicle has an OBD1 computer system. You don't need a scan too to get codes. Here is a link that explains how it's done:

https://www.2carpros.com/articles/nissan-obd1-diagnostic-trouble-codes-and-retrieval-procedure-1984-to-1994

If the light isn't on or there are no codes, I would check and confirm fuel pressure to make sure it isn't low. Here is a link that explains in general how to test pressure:

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

Here are the directions specific to your vehicle. It includes pressure specifications. The attached pics correlate with the directions.

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1994 Nissan-Datsun Truck Pathfinder 4WD V6-2960cc 3.0L SOHC MFI (VG30E)
Component Tests and General Diagnostics
Vehicle Powertrain Management Fuel Delivery and Air Induction Fuel Pump Fuel Pressure Testing and Inspection Component Tests and General Diagnostics
COMPONENT TESTS AND GENERAL DIAGNOSTICS
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.
- Do not perform fuel pressure check while fuel pressure regulator control system is operating; otherwise, fuel pressure gauge might indicate incorrect readings.

PROCEDURES
1. Release fuel pressure to zero.
2. Disconnect fuel hose between fuel filter and fuel tube (engine side). Then install pressure gauge.
3. Start engine and check for fuel leakage.

Fuel Pressure Gauge

pic 1

4. Read the indication of fuel pressure gauge.

pic 2

SPECIFICATION AT IDLING

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

Vacuum/fuel Pressure Test

pic 3

8. Start engine and read indication of fuel pressure gauge as vacuum is changed.

NOTE: Fuel pressure should decrease as vacuum increases. If results are unsatisfactory, replace fuel pressure regulator.

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Please keep in mind, there are other things as well that can cause a power loss such as a faulty crankshaft position sensor, plugged catalytic converter and so on. If you can think of anything that may help me diagnose what is happening, let me know. For example, there is black smoke from the exhaust. It runs rough when it finally starts. Anything you can think of.

Also, I realize most people don't own a fuel pressure gauge. However, most parts stores will lend on to you to use.

Take care and let me know what you find or if you have other questions.

Joe