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Can't figure out what's wrong with my Z. Cranks but take forever to start.

9K views 41 replies 5 participants last post by  kanedaZ350 
#1 ·
What's up guys , I'm new to the site, to start my name is George and I own a 2006 brickyard 350z which I manual swapped last year.

Last month I changed the battery and the car decided to mess with me. It cranks over strong and after about 5-7 cranks it will start. But after driving it it take 5-10 minutes to want to start again.

I started with changing cam and crank sensors, then renewing all the grounding points under the hood. followed by checking for broken or corroded wiring. I check the NATS as well and still having the same issue.

My CEL is showing u1000 but I'm guessing that's cause the car used to be auto and is now missing the TCM.

My IPDM makes a clicking sound from the starter relay which I have also replaced it clicks on and off every 5 secs or so. I have ran into a dead end here as I have no idea what to do next. The car runs amazing once it starts but getting it to start sucks and is embarrassing when out in public lol.

If you guys could help I would seriously appreciate it. I have asked 3 groups on Facebook and no one knows what to do almost like no one works on there own cars anymore.

Any questions you guys have ill be logging in every 1-2 hours. I really want to start driving my Z again so please ANYTHING you can think if will help.
 
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#2 ·
Welcome George- I suggest you look at your fuel pressure regulator (FPR). The VQ needs adequate line pressure to gain an immediate start. If the fuel pressure regulator becomes defective, that pressure drops off and needs to be cranked a few times to build up again. Check your FSM for more specifics on location and procedure for changing the FPR.
 
#3 ·
Ok, ill check into that, someone told me to check my negative cable as well, it was super hot so ill be replacing that too. I do have a whole other motor I could pull the FPR off of and see if that makes a difference. Question, do VQ's have 2 FPR or just the one?
 
#5 ·
So today I changed the negative battery wire and terminal, had battery tested and its great and changed the dampeners at the end of the fuel rails. No improvement. I also changed the vvt sensors on the front of the motor and nothing either. Motor only has 47k on it and its never been run dry on oil or overheated, I cant think of anything else.

I might just purchase another crank sensor and see if maybe the one I bought is defective on Friday.

Any other ideas is appreciated to anyone with input. I am running out of ideas. When it turns on its a champ its just starting it that is being a pain!!! lol
 
#7 ·
So I looked online and it said the FPR is built in to the pump itself, also read that the fuel dampeners are what hold the constant psi for the fuel lines something about because its not a recirculating fuel system( i know my explanation must sound handicapped sorry). I had some laying around so I changed them.

No improvement meaning the car still takes 4-8 cranks to start up. It never cranks on the first try and after driving it take 5-10 minutes before it will start again.
 
#9 ·
Captains log day 58. (lmao but seriously been almost 2 months of dealing with this)

I bought starter fluid today and decided to spray around the intake manifold area and wouldn't you know it, the car started instantly. Now I'm thinking that I have a vacuum leak somewhere around the intake plenum spacer and throttle body.

I will be disassembling everything and checking/replacing the gaskets in and around the manifold to see if I can finally get this Z to start on the first turn every time.


I'll post results by tomorrow once everything is done.
 
#10 ·
Well, no positive results.
At this point i have:
Change crank sensor twice
cam sensors twice
check all my ground
changed O2 sensor (sensor 2 bank 2)
resealed the intake manifold
replaced fuel damper/regulators
checked for spark and fuel
MAF sensor is confirmed working
the Z has actually gotten harder to start.....

IDK anyone in the Fort Myers Fl area that might be a guru, honestly I'm willing to pay someone to come here and tell me what has to be fixed.
 
#15 ·
Is there any way to test or know if the timing chain is stretched? Lots of people keep saying it could be that. The car only has 47k of which i have only put 5k on. I bought it from an old guy in his 60's and it was auto, I doubt the old dude was tracking the car when he drove it to play golf lol.
 
#16 ·
There's no way to "test" a timing chain unless you remove it. Any stretch would have to be from an underlying cause and there wouldn't be any reason to replace it at 47K. BTW- I'm an "old dude in his 60's" and still hold an SCCA competition license to actively race around the country. Met plenty of younger Z drivers who play golf and have no idea what their cars are really capable of.
 
#20 ·
Ok so today I made the appointment with Nissan for next week to have it diag. So far i did change plugs and a friend hooked me up with a DW 255 fuel pump fo freeeeee lol car still remains the same hard to start but it does start and once its hot its even harder. while i wait for the appointment with Nissan next week I'm going to get a ohm/voltage meter and i am going to test all the sensors i have changed.



Was told that my issue does sound fuel related, possibly either the main damper from the fuel line to the rail or...... its getting vapor locked because of clogged fuel vent lines... all that is Chinese to me so if anyone can explain what to look at i would really appreciate it.
 
#24 · (Edited)
OK- here's the FPR in my '03 track model. It's on the PS of the engine bay, next to the plenum with the battery to the left.
View attachment 53315
ok so I did replace that as a damper or at least that's what i was told it was buy the parts store.

I did a fuel pressure test and it came back 51 psi with key in on position and 64ish while running both numbers stayed consistent thru never lost pressure.
 
#27 ·
40-42 PSI is low for resting line pressure on a VQ35DE. 50-52 PSI usually guarantees a quick start, but you're building line pressure by starting the car several times. Since you've measured it a few times and not found any leakage, I suspect your fuel pump is defective. How many miles are on this Z?
 
#28 ·
I just replaced the fuel pump with a DW aftermarket pump and my Z currently has 47200 miles on it.

While cranking it isn't building pressure either like I thought it would just keeps at 42psi while the pump is priming it does go to 53psi but once it stops priming it dumps back down to 42psi
 
#29 ·
FIXED I THINK!

So i was reading up on other post on the site and came across someone having the same issue. Someone suggested to do a key reset where i turn the key to the on position for 5 sec and the off for 10 sec and start the car. the car is going an hour now starting with no issues at all and on the first try every time.

I will be driving it tomorrow for about an hour to see if it sticks and the issue is solved so she can stay on the road.

Let you guys know tomorrow!
 
#32 ·
Drove car this morning for about 35 minutes got home and had to do the key reset again but she starts every time at this point. I cleaned the throttle body and now it seems like I have to give a very small amount to start the car after it warms up but like I said I can actually drive it again!

I'll probably reconfigure the Throttle with the repair manual reset, maybe that will fix the need for throttle to start but overall, she's back!

Thanks to all you guys and especially dkmura. your the real mvp!
 
#34 ·
Short lived lol the car after being driven for about 2 hours decided to not want to start at all after it warmed up. waited til this morning and it took about 8 turns before it finally started. Im honestly puzzled at this point. Someone suggested to replaced the fuel pump assembly as it has a regulator that is known to go bad. In other words the pump works but it doesn't hold pressure in the line and after it works for a while (gets hot) it quits working properly making it hard to build any pressure and start the car.... IDK where to go from here.
 
#38 ·
Well I have swapped out the throttle body and still having the same issue. Im going to have to change the cam sensors again, they guy who sold them to me let me know a few days ago that he has had them in his tool box for over 5 years so it might be possible that they are actually bad. they seem to work when cool but once they do some work/reading and heat up they fail.
Really not too much left to change here im figuring either the sensors, FPR, or ECU at this point.

Anybody want to share an issue similar to mine that got it solved please lmk what you did cause im bummed out at this point. Havent been able to take my car out and enjoy it in months now.
 
#39 ·
Based on my previous problems, I would check coil packs next. Perhaps they’re getting hot and failing on the restart. Perhaps you can just ohm them out before and after. Stick with the basics of air, fuel, and ignition. Good luck!


Sent from my iPhone using Tapatalk
 
#40 ·
Well today i replaced the cam sensors with new oem ones. still having the same issue tho. I did notice that if the car is running and I turn it off and immediately turn the key to start it, it starts everything. but if i wait more than 5-10 sec its take 5-7 trys to start again.

So my question is, does that sound like a fuel related issue? I changed all my coil packs my maf is new and works perfect, everything is showing signs of fuel being the issue. on crank my fuel pressure is only about 44-50psi while running it sits great at 62-64psi.
 
#41 ·
Well today i replaced the cam sensors with new oem ones. still having the same issue tho. I did notice that if the car is running and I turn it off and immediately turn the key to start it, it starts everything. but if i wait more than 5-10 sec its take 5-7 trys to start again.

So my question is, does that sound like a fuel related issue? I changed all my coil packs my maf is new and works perfect, everything is showing signs of fuel being the issue. on crank my fuel pressure is only about 44-50psi while running it sits great at 62-64psi.
I am also having the 6-10 crank try embarrassment in my 04 Z . However, mine only hits me about every 4th or 5th trip. It’s bizarre. I thought it might be a flaky key-immobilizer glitch but it does seem to happen way more after long hot daily commutes here in the South US. I am following the same guesses. I went to new ngk iridiums , new CAI, cleaned then Replaced the MAF, seafoamed the intake to get rid of the years of blowby neglect previous owner inflicted on the intake , added catch can. Still does the nothing every few trips. I think I will try the FPR next before the cam sensors. In all fairness I had a wet plug when I got it so I just thought valv covers and gasket job, plugs , new oil, high octane and some hard pulls would clean the crud out. 6 months later now. No change. Humble pie here
 
#42 ·
What’s up bud, it’s been 8 months and I have got no closer to sorting it out. Took it to Nissan and they say that on paper my car is perfect they can’t find out what’s going on. They told me to try to put my cats back on cause I have test pipes to see if that helps.
 
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