Pathy random no start

RatLabGuy

RatLabGuy

You look like a monkey and smell like one too
Joined
May 18, 2005
Location
Churchville, MD
Stock 08 Pathfinder, 4.0, 188k miles

Car runs great, pretty new battery.
3 times now, it has randomly not started. Turns over just fine... turning key it just cranks and cranks like there's no fuel (air?). Then after some random amounts of tries, turning off then back on again it fires up and runs fine. No stumbling, chicking or anything like I'd expect if it were flooded or something. This last time I tried several times w/o luck, gave up, tried again tonight, fired up on the 3rd trrial. Prrior to this had been easily 2 dozen normal starts.
No CEL or anything reported from OBDII.

Any ideas?
 
If there is a shrader valve on fuel rail check if there is pressure after no start, should be residual pressure if fuel pump is working, listen close on key up before start, you should hear relays and pump if you don’t have the radio and blower fan on.

fuel Pump relay and or pump motor would be more likely random disfunction than ignition, but there could be an ignition relay as well.
these are general suggestions, I’m not familiar with the vehicle at all, these are some of the things I listen for on the machines I work on When I can actually hear
 
The randomness is what I can't get my head around. I'd think if a relay were bad, it would just be bad...?
unfortunately it cranks perfectly find now so I can't check fuel pressure etc.
I've read of the cam and crank position sensors going bad on these vehicles but there's no OBDII codes like I'd expect with those.
 
ignition switch?
 
when I hear intermitten fault my fist thought goes to electrical ground...id be curious about the ecm control ground or the ignition module ground
 
Ron said:
when I hear intermitten fault my fist thought goes to electrical ground...id be curious about the ecm control ground or the ignition module ground
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This is a possibility - however I would think that it would come and go with some movement of the vehicle or something (??) . If everything is sitting static, what would cause the ground to work one moment and not another? Or rather... not, not, noy, yes, yes, yes without it moving? The limited ataset thuse far is that once it works, it works for awhile.
 
I had similar symptoms with an expedition. Fuel pump was on its way out. Lines weren’t staying primed. It would take more turns to crank or you’d have to cycle the key a few times to prime the lines. Replaced pump and all was good. Not saying that’s your issue, just spitballing.
 
Wes said:
I had similar symptoms with an expedition. Fuel pump was on its way out. Lines weren’t staying primed. It would take more turns to crank or you’d have to cycle the key a few times to prime the lines. Replaced pump and all was good. Not saying that’s your issue, just spitballing.
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Did it randomly work well? Or did it just get slower to catch over time?

I do think it is something either in fuel delivery or in a sensor that tells it to. Since it fires and runs perfectly fine when it does catch, that suggests its not getting flooded like its an air blockage or A/F kind of issue.
 
RatLabGuy said:
Did it randomly work well? Or did it just get slower to catch over time?

I do think it is something either in fuel delivery or in a sensor that tells it to. Since it fires and runs perfectly fine when it does catch, that suggests its not getting flooded like its an air blockage or A/F kind of issue.
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It ran flawless once cranked. Didn’t stumble or anything. Yes, it was random. Sometimes it would fire right up, other times it would take a few extra spins. I finally figured out it was fuel delivery when I would cycle the key a few times to prime the lines. It would fire instantly when I did that.
 
Wes said:
It ran flawless once cranked. Didn’t stumble or anything. Yes, it was random. Sometimes it would fire right up, other times it would take a few extra spins. I finally figured out it was fuel delivery when I would cycle the key a few times to prime the lines. It would fire instantly when I did that.
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interesting point about the key cycle priming the pump. The other day it wouldn't start, I went to go pull OBDII codes on it, so I cycled the key a few times, and it fired up. Maybe chance... maybe not?
 
Is the no start condition when it is hot, cold, or both?
 
drkelly said:
Is the no start condition when it is hot, cold, or both?
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Ditto... have been working on an issue with stepsons '05 CR-V (converted RH drive mail delivery vehicle) with random HOT no starts.
USPS requires them to shut off the vehicle to walk a package to door/porch... when it happens, 20-30 minute wait and it fires right up
Given the removal of 75% of the pass side plastics (glove box/valance/etc.) during the RH "conversion" (definite half-ass Bubba job) wiring was suspect.
Typically happened during the summer (90*+ days), but recently began happening when he began using the heat... which dumps out directly on the ECM/relay area due to Bubba's removal of the footwell ducting...

Hoping it's not a cold joint in the ECM or skint wire/short in the rats nest, we went with simplest/cheapest first... swapped the Fuel Pump & Main ("PGM-FI") relays, which are apparently common suspects... and added a baffle to the heater (duct-tape).

So far, so good...
 
Wes said:
It ran flawless once cranked. Didn’t stumble or anything. Yes, it was random. Sometimes it would fire right up, other times it would take a few extra spins. I finally figured out it was fuel delivery when I would cycle the key a few times to prime the lines. It would fire instantly when I did that.
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I had this same thing happen on our '12 Durango. Didnt worry too much about it, because it seemed very random. Took the vehicle in for service, and they did a few recalls. One was the fuel pump module. Never an issue after that. They said the recall for it caused no-start issues.
 
drkelly said:
Is the no start condition when it is hot, cold, or both?
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Can't tell, don't think it matters...? Its only happened 3 times, but ever time it was NOT right after having just gone somewhere. E.g. not hot engine. Twice the car had been sitting about 2 hrs, most recently after sitting days - but weather wasn't especially hot ot cold or anything.

I'm leaning the most towards the fuel pump. Funny thing is, this was wife's car for several years, I've never really paid attention to whether you normally can even hear it priming.
 
RatLabGuy said:
Can't tell, don't think it matters...? Its only happened 3 times, but ever time it was NOT right after having just gone somewhere. E.g. not hot engine. Twice the car had been sitting about 2 hrs, most recently after sitting days - but weather wasn't especially hot ot cold or anything.

I'm leaning the most towards the fuel pump. Funny thing is, this was wife's car for several years, I've never really paid attention to whether you normally can even hear it priming.
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I can hear it on my TJ, but I can’t hear it prime on any of my other vehicles either.
 
Some headway. Perhaps.

Went to drive the car lat Tuesday, it wouldn't start again. tried several times, no luck. We were in a hurry so we gave up and just took another vehicle.
Tonight I got to thinking about it and went and tried again.
First try, stuck key in, no sound, nothing. Pulled it out, back it, heard pump... cranked up. WTF. Grrr.

Then I realized, wait I heard the pump (had the door open) but had not previously.

After a lot of attempts, I realized the pump only primes the first time after you put the key in. In other words, stick key in, turn on, it whirrs. Turn of, then back on, no whirr. Turn off, pull out key put back, it goes. So it must have some kind of sensor that differentiates the first turn on after insert from just turning on.

But it only primes *most of the time* when doing this. several times, no sound. Unfortunately since I'd previously cranked then stopped it, even wo a prime, it starts anyway after a vew revolutions bc its still reasonably primed.

So the point is the pump is randomly not running. Would this mean the pump itself would require placing, or possibly something in the circuit that tells it to run?
Any idea if this car has a pressure feedback circuit doing that?

As previously mentoned - car runs great once started.
 
83oldyoda4x4 said:
Could it be a weak fuel pump/clogged filter sock? Not getting up to desired psi consistently.
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Were this the case, wouldn't the motor still spin every time and make noise, and just not be effective sometimes?
 
I too would suspect the fuel pump. The computer probably has a timer that says it doesn't need to be re primed within so many minutes of a start attempt. (Why you didn't hear it the second time.) Or it has a pressure sensor that tells the computer that there's enough pressure without priming. (If it has this it could be your problem) If it has a schrader valve on the fuel line you could release the pressure and see if it re primes or you get a no start. Also check to see if there's pressure the next time it wont start.
 
rattlecanpaint said:
If it has a schrader valve on the fuel line you could release the pressure and see if it re primes or you get a no start. Also check to see if there's pressure the next time it wont start.
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I believe thsi is the best way to diagnose it... but I haven't found a valve anywhere yet. There may be one I just haven't seen it. Gotta dig around.
Its still happening randomly. I do feel like now we can get it to start ore reliably by pulling the key out, putting it in, turning, waiting a sec to hear it run, then crank.
 
I have the same problem with my Silverado. It's 100% the fuel pump on its last legs. It's a known problem for my truck so I'm assuming your's is the same by the symptoms.

Mine has been doing this on and off for a year now. I really should do something about it.
 
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