1999 pathfinder won't start when hot

[Bill1999]

I have a 1999 pathfinder/qx4 with 192K miles. Starts up fine in morning and I can drive somewhere for at least 30 minutes. I shut it off and it will not start for several hours..until it gets cold which is aided by the fact we have some snow right now. Engine cranks fine and fires a bit like it is trying to start. Disconnected the MAF but no luck. Coolant sensor seems to be ok..reads around .250 kohms when hot. Any ideas on what this could be? It threw some codes and I had a downside o2 sensor changed yesterday. Have only driven a couple of miles but no codes so far.

[Towncivilian]

Welcome to NICO!

Downstream O2 sensor should not cause any starting issues.

ECTS sounds good based on the resistance value, great thinking to check that first.

Have you scanned for codes to ensure there are none pending and not yet illuminating the SES light?

[Bill1999]

Thanks for the suggestion. Just checked it but my check engine light was not on. Have a code P325. Knock sensor 1 circuit bank 1 or single sensor. So...maybe single sensor? Engine was cold and started right up!

[Bill1999]

Any great mechanics out there? I still have this problem. Does anyone know the cold start process flow and how it is different than a hot start? I think I just have a bad sensor or valve. Thanks!!!

[Bill1999]

SUCCESS I decided to clean my MAF on the theory it can't hurt. Now the problem is gone! Yahoo!!!

[Towncivilian]

Glad to hear that it was such a simple fix. Can't believe I overlooked that suggestion too!

[Bill1999]

OK Fast forward a long time. This starting problem continued to hound me. Would not start when hot. Final resolution was a new distributor. This cured it permanently. I was surprised and had to get it towed to a garage to get the diagnosis.

[ginopathfinder]

i have a 1999 pathfinder and the same thing happens to my car.First the mechanic wouldnt be able to read the code on obd and cleaned the Throttle Position Sensor and I kept driving the car like this for couple months and later on i got stuck on the highway because the distributor died on me and I replaced the distributor but after 2-3 months later it start doing it again and this time they were able read the code saying p035 knock sensor circuit 1 malfunction ( which is the crankshaft position sensor} :

[ginopathfinder]

i made some searching on the web and I read that the distributor and the crankshaft position sensor kind of cover each other.if you have a bad crankshaft sensor your distributor will keep you going for a little while but eventually if you don't replace your CPS your brand new distributor will gone bad shortly.

[centralcoaster33]

Hey Gino, welcome to NICO Club!

This thread is a couple years old so you might not get any responses or conversation out of it (date for each post is in the upper left corner of that post), but your information could be helpful. I think it's cool your first posts are trying to help others.

You can introduce yourself in a general section or your specific car section or just hop right in and comment, you can use the search feature for drilling down into specific topics, you can post in classifieds, you can request a NICO member discount at our sponsoring businesses, you can get access to your Factory Service Manual for specific procedures on your car, and more! I hope you get some good use out of your new account.

[AlexD]

Had the same symptoms on my 2000 Pathfinder 3.3L with 185k miles: P0325 code (may be unrelated), and intermittently very stubborn starting. The problem starting was most likely to happen when engine had reached full temp in the summertime (ambient 95F) and then left off for about 15 minutes, such as going into a store. Upon coming back, it might fire up for a moment, and then stall and refuse to start. Then take a huge amount of starter cranking to get it to sputter back into life after a few minutes.

The problem in my case was a worn out fuel pump. It was delivering only 17 PSI. 30-45 PSI is considered normal range. For the most part the car didn't appear to be fuel starved when driving (not many misfires). Although after the replacement it did seem to get a little extra engine power. On very rare occasions it started to misfire and lose power when getting to 3-4k RPM, but that was infrequent.

I found this thread when searching for answers before finding the solution so this may help others. Fun fact: Pathfinder fuel pump is below the drivers side rear seat and is accessed through an access hole.

[nphabian]

I have the exact same symptoms. Starts up perfectly when cold and then runs like a champ. I have no codes. No CEL. No misfires. Reasonable mileage. No loss of power. No stalling.
Only problem that she won't stop (easily) when she is hot.
Distributor is pretty new and the whole distributor assembly looks pretty nice. Also plugs and wires are new.
I tested for spark when the problem appears and I feel like it seems alright ... I am getting +- a spark per second while cranking, which seems reasonable.
I replaced the fuel pressure regulator and feel like it got worse since then.
I also replaced the crankshaft sensor a couple of weeks back and I felt like it was getting better. Mileage improved and problem seems to occur less. However it still sometimes appears.
Since spark seems alright, I am guessing fuel (pressure) related. And probably should do a pressure test. But I have no idea where to go next then.

[nphabian]

In the meantime I saw a pending (!) camshaft-sensor error on the ODBII scanner. Figured I might as well try to replace the distributor. And that seems to have done the trick. Starts up every time, no matter if hot or cold ...