Thinking if this is the issue I’m having:

Cold start with first turn of key.

Warm and hot start is extended crank, and now the tach drops to 0 unless I give it gas. Issue getting worse. Replaced everything fuel related except the pump. But thing is, I don’t have any issues when driving. Except I am noticing a bit of sluggishness on acceleration.

286,000. Not sure if pump been changed before or not. Wonder if it could be coils, or camshaft sensor in front (though it doesn’t give any codes relating to camshaft).

I am getting a P0174 bank 2 system too lean.

Tach dropping out is a clue, almost all Nissan ECM's get RPM exclusively from the crankshaft sensor. Many times they get weak (especially when warm) and miss pulses at cranking speed, but they don't flatline and read normally once the engine fires and the reluctor speed increases. So you get cranking issues but no codes

I think the bigger question is have you EVER replaced a fuel pump? If so, this should be pretty simple. I think in the FSM you need to release the straps so you can tilt it back and unbolt the pump but should be pretty easy.

Your lean code is most likely a vacuum leak. Have you done a smoke test?

Ludeaem wrote: ↑

Tue Dec 22, 2020 8:57 pm

I think the bigger question is have you EVER replaced a fuel pump? If so, this should be pretty simple. I think in the FSM you need to release the straps so you can tilt it back and unbolt the pump but should be pretty easy.

Your lean code is most likely a vacuum leak. Have you done a smoke test?

I haven’t replaced one before...lol.

Come to think of it: it probably was just a stored code. I did have 2 vacuum leaks, install gasket and something that looks like the egr next to the egr...a Rubber hose was half disintegrated. All vacuum leaks have been fixed 2 weeks ago though. No more erratic idle or 2,000 RPMs on cold startup.

VStar650CL wrote: ↑

Tue Dec 22, 2020 7:15 pm

Tach dropping out is a clue, almost all Nissan ECM's get RPM exclusively from the crankshaft sensor. Many times they get weak (especially when warm) and miss pulses at cranking speed, but they don't flatline and read normally once the engine fires and the reluctor speed increases. So you get cranking issues but no codes

Hmm very interesting clue. I changed the crankshaft sensor already. The one under the car. Replaced with a new one. I did pull the camshaft sensor, the one in the front that has the little spinny thing on the end. It had some play but I read the FSM says it’s purposely over-centered. However, I only cleaned and examined it and changed the o rings. A new one is $136 the cheapest. Though many parts stores have it for between $300 and $500. So, a $50 fuel pump sounds a lot better.

Like I say, I’m still about to tap out and take it to a mechanic for a full scale diagnostic. But problem is, I cant afford for them not to get it right.

For example: I had the dealer of Infiniti and my trusted local shop diagnose a vibration coming from rear when braking. Both places said brakes looked fine and had me changing out control arms and bushings up the wazoo...which helped straighten my camber, but did nothing for the vibration. Few months later, calipers lock up and strip the rotor. $500 and 3 months later, issue solved. But that’s downtime lost. Anyway, off topic...

You could always diagnose the problem instead of throwing fuel system parts at it in hopes of fixing it - it's far more effective and costs significantly less. Get a fuel pressure gauge and see what your fuel pressure actually is, instead of replacing a fuel pump that may not be the problem.

Ryantzer wrote: ↑

Wed Dec 23, 2020 10:16 am

You could always diagnose the problem instead of throwing fuel system parts at it in hopes of fixing it - it's far more effective and costs significantly less. Get a fuel pressure gauge and see what your fuel pressure actually is, instead of replacing a fuel pump that may not be the problem.

Thanks. I just scheduled an appointment with my local shop earlier today. But they can’t get me in til next week.

Even though I’ve thrown parts at it, some have made improvements to gas mileage and overall drivability. Stuff like fuel filter and injectors were due anyway. Only thing that I changed that seemed okay, was the fuel pressure regulator. A couple of the injectors fell apart upon removal and were leaking internally.

I’m just at a point where it’s beyond my expertise at this point.

Update:

Took in for diagnostic: the tech initially said it sounded like a fuel pump at start up, but further testing revealed it to be a fuel pressure damper leaking off. The same one that looks like the fuel pressure regulator that I had replaced. I was shocked, but not surprised considering that was going thru my mind as well, because there are various fuel valve things throughout the fuel system.

The part is obviously nowhere in stock immediately, but seems to be cheaper coming from the online Infiniti versus the parts store. Looks like I’ll be waiting another week to see if this fixes it. But glad I don’t have to do the fuel pump process this time.

Update: good news, issue solved! Finally. In a way I feel stupid that I didn’t catch this earlier, but it was that main damper that catches the fuel from the tank. It was leaking so full of fuel in the vacuum line, that the engine would run for a bit, even with the fuel pump fuse removed (when doing the release fuel pressure step). It’s basically a fuel pressure regulator, but the difficult one under the plenum is the one I went for first.

The good news is, all the other fixes I did that didn’t fix Th e problem, did solve a lot of other issues in the process. Mainly the elusive vacuum leak coming from the intake manifold gasket, that no mechanic was able to figure out (I didn’t get it specifically diagnosed, but I did have a shop say it was a vacuum leak “somewhere” causing it).

That said, I did change fuel pump last week on my Maxima. Fairly easy fix, but wasn’t something I enjoyed doing. It did fix a blinking check engine light that I was getting on highway acceleration, but still chasing down another issue that might be linked to the coils or exhaust.