# 97' hard to start when warm



## dcorazal (Sep 19, 2005)

I have a 97 path with 140,000 miles, runs great and still gets good mpg. Cold starts are fine, but after the engine is has been running and it sits for 10 minutes to an hour it starts hard. I need to press the accelerator slightly to get the engine to start. I has been a while since the last tune up, may be 50,000 miles. I replaced the plugs, (NUMBER SIX WAS NOT FUN!) they didn’t look bad and did not fix the problem. I have the other tune up parts on order ( wires, cap&rotor, pcv, air filter, fuel filter) and am running some injector cleaner through a tank full of gas.
Just wondering if anyone has any advice or insight, I searched all the forms and didn’t get any help so far. Any thing to look for. CEL is not on.
Thanks


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## dcorazal (Sep 19, 2005)

dcorazal said:


> I have a 97 path with 140,000 miles, runs great and still gets good mpg. Cold starts are fine, but after the engine is has been running and it sits for 10 minutes to an hour it starts hard. I need to press the accelerator slightly to get the engine to start. I has been a while since the last tune up, may be 50,000 miles. I replaced the plugs, (NUMBER SIX WAS NOT FUN!) they didn’t look bad and did not fix the problem. I have the other tune up parts on order ( wires, cap&rotor, pcv, air filter, fuel filter) and am running some injector cleaner through a tank full of gas.
> Just wondering if anyone has any advice or insight, I searched all the forms and didn’t get any help so far. Any thing to look for. CEL is not on.
> Thanks


Update: Tune up didn't help.

Does anyone know if there could be a code that is triped without the CEL on. I'm thinking I may have a sticking injector?


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## dvdswanson (Nov 6, 2005)

check the MAF, IAC, and TPS. then I would check the fuel pressure, for the pump and regulator.


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## dcorazal (Sep 19, 2005)

dvdswanson said:


> check the MAF, IAC, and TPS. then I would check the fuel pressure, for the pump and regulator.



Thanks for the reply:

I pulled out the MAF and cleaned it with electrical contact cleaner. No luck

I went to Autozone this morning and had the OBD read and got a P0325 (Knock sensor)

Could the knock sensor cause hard starting?

I noticed the hard starting has happened when cold but only ocationally.


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## dvdswanson (Nov 6, 2005)

yes a knock sensor can cause hard starts, check your connector too. who knows you may have had a little friend try to dine on the wires.


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## dcorazal (Sep 19, 2005)

Finally getting around to working on this problem: I have had the CEL come on and through a P0300 (engine misfire). Hard starting when warm is still the issue. 
I bought a fuel pressure tester and performed a fuel pressure check per the manual.
Here’s how it went.
1: Removed the fuel pump fuse and let engine die, and then cranked the engine over several times. Removed the fuel line from the rail and gas shot all over. WTF I guess there was still pressure in the line. 
2: Next: When I pulled off the vacuum hose from the fuel pressure regulator to the manifold there was gas in the vacuum line????? *Could the fuel pressure regulator be internally leaking?*3: Ran pressure check and pump with regulator disconnected was at 43psi like to should be. Then connecting the external vaccum source to the fuel pressure regulator was able to get the pressure down to 34psi like expected.

Someone please tell me that the fuel pressure regulator vacuum line should not have fuel in it.


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## golfer (Aug 21, 2006)

I would think it's safe to say there should be *no *fuel in a vacum line.
Btw... with the gauge installed did the pressure hold for a while when the engine was turned off ??

Check this thread from someone with an X-trail having " hot soaked " starting issues.http://www.nissanforums.com/x-trail/127006-difficult-start-when-hot-soaked.html


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## dcorazal (Sep 19, 2005)

The guage did hold for a while, maybe 15-20 minutes. One web site i found said the pressure should hold over night. I did a search on google and found this Troubleshooting Electronic Fuel Injection Problems it clearly states to look for fuel in the vacuum line. The leak in the diaphragm must be small but big enough to cause the problem. I'm ordering a regulator today. This is going to be a project. The Throttle body has to be removed to get to the regulator. I'll keep this thread going untill Its fixed.


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## dcorazal (Sep 19, 2005)

Fixed!!!! Fuel Pressure regulator took care of it. Starts perfect now. Removing the manifold was not that bad of a job.
Hope this helps some one.


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## dvdswanson (Nov 6, 2005)

thanks for the update.


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## sonaris (Apr 21, 2008)

dcorazal said:


> Fixed!!!! Fuel Pressure regulator took care of it. Starts perfect now. Removing the manifold was not that bad of a job.
> Hope this helps some one.


Howdy, I have similar problem with my PathFinder. Starts fine cold (more often than not) but hard to start if you let it sit for more than 10-15 minutes after it has started. Otherwise, it runs great.

If you don't mind me asking, do you have any tips on getting to the Fuel Pressure Regulator, seems to be in a tight spot. Did you have to replace any other parts (gasket) while servicing the FPR?

Thanks!


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## dcorazal (Sep 19, 2005)

It was a over 2 years age that I replaced that fuel regulator. I had to re-read the post in order to remember what a pain that problem was. These fourms have helped me and saved me so much time and money I am glad to help someone else. 
If I remember correctly: The fuel regulator is on the back side of the motor towards the firewall. It connects to the fuel rail and the fuel rail runs under the intake manifold. I would follow the directions in a shop manual as it pertains to removing the intake manifold. Remove the throtel body, drain the coolent and oil, mark all connections, remove intake manifold, etc.
I have worked on my own cars for years so I did'nt think that was to bad of a job. Test the FPR before you go through all that work. I remember that once I removed the Intake or throtle body i could tell the FPR had been leaking. What is was doing was leaking into one of the cylinders (#6 i think) and flooding out that cylinder. The intake on that cylinder was completely clean while the other ones were carbon coated. Flooding that cylinder after 10-15 minutes caused hard starting, Leaving it over night the fuel must have evaporated and not caused the hard starts?

I remember that I had a 97 Altima at the time and the fuel regulator would have been a 5 minute job to replace.

Good luck!


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## sonaris (Apr 21, 2008)

dcorazal said:


> It was a over 2 years age that I replaced that fuel regulator. I had to re-read the post in order to remember what a pain that problem was. These fourms have helped me and saved me so much time and money I am glad to help someone else.
> If I remember correctly: The fuel regulator is on the back side of the motor towards the firewall. It connects to the fuel rail and the fuel rail runs under the intake manifold. I would follow the directions in a shop manual as it pertains to removing the intake manifold. Remove the throtel body, drain the coolent and oil, mark all connections, remove intake manifold, etc.
> I have worked on my own cars for years so I did'nt think that was to bad of a job. Test the FPR before you go through all that work. I remember that once I removed the Intake or throtle body i could tell the FPR had been leaking. What is was doing was leaking into one of the cylinders (#6 i think) and flooding out that cylinder. The intake on that cylinder was completely clean while the other ones were carbon coated. Flooding that cylinder after 10-15 minutes caused hard starting, Leaving it over night the fuel must have evaporated and not caused the hard starts?
> 
> ...


Sorry I didn't pay attention to the date of your original post... It's been a while (2 years ago). However thanks for taking your time to send a reply!

The forums have been quite helpful for me as well.


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