2001 Pathfinder Rough Start

[joshlobe]

Newbie here. I have a 2001 pathfinder LE 4x4. It has an intermittent rough start issue. Sometimes she will fire right up. Sometimes she will crank for 10 seconds with nothing. Sometimes she will crank 3-4 seconds, then try to catch and sputter for a second, then die. Then try to start again, and she fires right up. I have found nothing to indicate any circumstances for replication. It might happen when cold, when hot, after driving for 2 hours, in the morning, at night... it's just extremely intermittent. Once she is started; she runs like a beast. No signs of rough idle, stalling, jumping rpm's, or anything like that. I can drive her for hours without any issues.

One more thing I noticed today; if I turn the air up to max AC, I will have more of a difficult time getting her started. She will still start, but very reluctantly.

She was taken in for service by my ex about two weeks ago; and had new fuel injectors, new throttle body, new plugs and coils, new air filter. But this problem has been ongoing for more than a year.

- I have replaced all (both) fuel pump relays under the hood as well as the fuse inside the cabin.
- When turning the key to "on", I can hear the fuel pump prime, but not every single time. Sometimes I turn to "on", hear it, attempt to start and get a rough start then die, turn it off then "on" again, don't hear pump, but she starts right up. Should I hear the pump prime every single time? Or only when it needs pressure?
- I have read about fuel pressure regulator. I have removed the vacuum line to the regulator and see no signs of wet gas or any smell of gas. I removed the fuel pressure regulator assembly and got gas spraying into my face, so I believe it is working fine.

I do not have the tools to test fuel pressure. I don't mind buying them, just not sure what I would need or how to test.
I also don't mind taking to a mechanic, but wanted to get an idea of what I could be dealing with here.

Any suggestions or input would be most appreciated.

[mdmellott]

There have been quite a few goodies replaced already so that narrows down the possibilities quite a bit. I would start by looking over the starter, it's power and ground connections, fix or replace any issues that might be found and then see if it starts up consistently normal.

[joshlobe]

Thank you kindly for the reply.

So the starter appears to be functioning correctly. Constant 12V is present. Switching 12V when cranking is present. And the ground is present. Starter always fires right up and I hear it trying to crank the engine. It never just spins (spindle not engaging crankshaft); as I know that sound, and would suggest a faulty solenoid. Everything appears good on the starter.

When I was just checking the starter; the car started 11 out of 12 times. 10 were flawless and fired right up. 1 struggled for a few seconds and then caught. One tried cranking for about five seconds, then caught and sputtered, and died. Next attempt she fired right up.

I'm seriously thinking fuel at this point. But it's odd it ONLY happens at startup. I can drive for hours with no issues.
I just replaced the fuel pressure regulator; and no change.
I also ordered the fuel dampener which should be here Tuesday.

Any other ideas?

[mdmellott]

Other than looking for grounding faults, like corrosion at the connector to the engine from the battery cable, it's hard to say where to begin with intermittent this issue.

[joshlobe]

Other than looking for grounding faults, like corrosion at the connector to the engine from the battery cable, it's hard to say where to begin with intermittent this issue.

Yes, that was my fear.
I dug out my old OBD scan tool; and scanned the vehicle and got back a P1135 and a P0505.
Now, lot's of things were removed/replaced over the last couple weeks, and I cannot be sure the last mechanic cleared codes after work.
I cleared the codes, and just finished a two hour long round of errands. I had no issues starting; and the codes have not yet returned.

All of my research has pointed to three possibilities (at least in my case):
1) Fuel Pressure Dampener
2) Fuel Pump
3) Air Intake Control Valve

I know a bad AICV can lead to frying the ECM. So I want to try to resolve this asap.
I am going to continue driving and see if any codes return.
I'll also install a fuel pressure gauge so I can monitor pressure during startups.

[joshlobe]

I would start by looking over the starter, it's power and ground connections, fix or replace any issues that might be found and then see if it starts up consistently normal.

Well, it turned out to be the starter. @mdmellot, I'm sorry for not having followed all the way through with your suggestion.
While it tested correctly with voltage and engagement; I failed to notice the bendix was not rotating solidly. It would rotate a little; then stop; then rotate some more.
It "sounded" fine... but it wasn't until I pulled the starter completely from the vehicle and ran it through a bench test. That's when I noticed it was not functioning correctly, mechanically.

It's back to starting right up and sounding great.
Thanks again for the perfect suggestions!

[mdmellott]

Excellent! I'm glad for you that it wasn't a matter of chasing down some elusive gremlin. It's also good to hear that pulling it wasn't a waste of time. I should have posted the starting system testing procedure so you didn't have to keep your fingers crossed to whole time until you confirmed it to be defective with the bench test. Better late than never, here's the section from the factory service manual which describes how to diagnose the starting system. >>> https://www.nicoclub.com/service-manual ... 1%2Fsc.pdf