Jeep failed to start

[BAPilot2]

After driving my Jeep most of the day yesterday, after stopping at a grocery store, I jumped back into it and found that it would not start. The engine cranked over, as normal, but would not start. I had over 1/4 of a tank of gas. I checked for codes with my scan tool but found none. The vehicle was running fine without any surging during the day and I had at least three previous shutdown/startup "key cycles" without any problems.

I left the vehicle at the grocery store for about 5 hrs before going to retrieve it at night. I was going to tow it home. I jumped in it and tried to start it one more time and it fired right up. It ran great as I drove it home.

Has anyone had this happen with their Jeep?

I use my Jeep as my daily driver, back and forth to work, and I'm hesitant to drive it for fear that it may leave me stranded for several hours if it fails to start once again.

I look forward to all constructive thoughts and comments.

(2005 Wrangler Unlimited - Rubicon - manual trans)

 

[AndyG]

Check your battery cables and the grounds ...also fuel pump backbleed is a known issue , could be it was close to starting and the next try got it.

 

[BAPilot2]

Battery cables and ground are all clean and tight.
I'm not familiar with "fuel pump backbleed" can you explain?
I tried starting it multiple times before having to call my wife to pick me up.
I'm thinking that it may have vapor locked and was not getting fuel when it was hot/operating temps. And once it completely cooled it started right up. Also, it just fired right up here in the driveway after sitting all night.

 

[AndyG]

Battery cables and ground are all clean and tight.
I'm not familiar with "fuel pump backbleed" can you explain?
I tried starting it multiple times before having to call my wife to pick me up.
I'm thinking that it may have vapor locked and was not getting fuel when it was hot/operating temps. And once it completely cooled it started right up. Also, it just fired right up here in the driveway after sitting all night.

There are a few threads , use the search engine...im no authority on it . @Chris ?

 

[Rubicon88]

Battery cables and ground are all clean and tight.
I'm not familiar with "fuel pump backbleed" can you explain?
I tried starting it multiple times before having to call my wife to pick me up.
I'm thinking that it may have vapor locked and was not getting fuel when it was hot/operating temps. And once it completely cooled it started right up. Also, it just fired right up here in the driveway after sitting all night.

But you should really test your battery.
When was it made? Odds are there will be a mfg date sticker on the side of it somewhere.

The batteries today don't last very long. (Hence the reason no longer a pro rated warranty. 3 yrs replace or nothing is now the norm.) The wrangler can be a finicky bitch with voltage. Not all of them but a lot will act very ignorant if the voltage isn't optimum.

I always chuckle when someone says vapor lock. That's really reaching into the bottom of the shit bag to throw at the wall. It didn't live it's 15 years and then today go hhhmmmm, we're vapor locking. Had you done an engine swap/fuel line replace recently then it's technically possible...(still unlikely in this platform) but it seems you just drive the thing to and fro like always but this time wouldn't fire for your trek home.?.

Back to your battery...
I own a repair facility and we see the most battery issues when the weather starts to break.
Why....heat is the #1 enemy of a weak battery. If your battery is old(er) and or in fair condition the heat can be just enough to kick it over the edge.

Checking it. You need a real battery tester. Not just a multi meter. You need to see the cranking amps weighted against the battery tag specs. It needs checked when cold. A charging test of the alternator isn't a bad idea as well.

One last note and other possible.
Fuel..but not vapor locked.
Fuel pump could be starting to go out. Fuel pumps can sometimes not work or enough to start but then a different time work as they should.
Usually fuel pumps go out or they don't but just like other electrical devices when they start to go can get their own odd behavior. (You know...like starter won't work...tap it lightly with hammer and it starts) type thing.
Just keep that mind

Good luck

 

[RichStep]

But you should really test your battery.
When was it made? Odds are there will be a mfg date sticker on the side of it somewhere.

The batteries today don't last very long. (Hence the reason no longer a pro rated warranty. 3 yrs replace or nothing is now the norm.) The wrangler can be a finicky bitch with voltage. Not all of them but a lot will act very ignorant if the voltage isn't optimum.

I'm not a mechanic and don't pretend to be one but if it was cranking and turning over, checking the battery would seem like the last issue here. Am I missing something?

I agree with the statement regarding life span of batteries....

 

[JKP]

The fuel pump only comes on for a few seconds when you attempt to start it if the engine doesn't start. If the check valve goes bad, the pressure will bleed down. To see if this is the problem, all you have to do is turn the key to ON for a few seconds, then OFF. Repeat a few times and this will build the pressure back up. Then try to start.

A failing fuel pump will often work when cold then fail when hot. Then work after it cools off.

Unfortunately they eliminated the schrader test port on the later years. So to test fuel pressure, you need a test kit. You can usually get these as loaner tools at local parts store.

 

[BAPilot2]

But you should really test your battery.
When was it made? Odds are there will be a mfg date sticker on the side of it somewhere.

The batteries today don't last very long. (Hence the reason no longer a pro rated warranty. 3 yrs replace or nothing is now the norm.) The wrangler can be a finicky bitch with voltage. Not all of them but a lot will act very ignorant if the voltage isn't optimum.

I always chuckle when someone says vapor lock. That's really reaching into the bottom of the shit bag to throw at the wall. It didn't live it's 15 years and then today go hhhmmmm, we're vapor locking. Had you done an engine swap/fuel line replace recently then it's technically possible...(still unlikely in this platform) but it seems you just drive the thing to and fro like always but this time wouldn't fire for your trek home.?.

Back to your battery...
I own a repair facility and we see the most battery issues when the weather starts to break.
Why....heat is the #1 enemy of a weak battery. If your battery is old(er) and or in fair condition the heat can be just enough to kick it over the edge.

Checking it. You need a real battery tester. Not just a multi meter. You need to see the cranking amps weighted against the battery tag specs. It needs checked when cold. A charging test of the alternator isn't a bad idea as well.

One last note and other possible.
Fuel..but not vapor locked.
Fuel pump could be starting to go out. Fuel pumps can sometimes not work or enough to start but then a different time work as they should.
Usually fuel pumps go out or they don't but just like other electrical devices when they start to go can get their own odd behavior. (You know...like starter won't work...tap it lightly with hammer and it starts) type thing.
Just keep that mind

Good luck

As far as battery age and testing goes... the battery is good. I used a battery load tester to verify that it is holding a load and maintains cranking amps. As for the battery age it is 1.5 years old although, age is irrelevant since, it holds a load as tested with a battery load tester.

As for vapor locking... you may view it as reaching into a bag of shit, grasping for something to stick, but it can and does occur on engines. Granted, fuel pumps being installed within the fuel tank and fuel injection systems have alleviated this occurrence to the point that it is almost nil, it is not out of the realm of possibility on any internal combustion engine. I used the term "vapor locking" due to the fact that I grew up working on carbureted auto engines and also, as a pilot and flight instructor, vapor lock on a naturally aspirated aircraft engine can and does occur due to overheating. If you find fault with the terminology then so be it. Maybe I should have stated that the engine seemed like it had a problem with fuel delivery. Either way the point I was making was that it seemed to be starved for fuel.

And to address your question regarding engine swap and driving to and fro... No. No engine swap. Still factory original with approximately 116,500 miles. And, Yes! I did drive to and fro with no related problems and then it failed to start after having sat in a parking lot for the 15 minutes I was in the grocery store.

 

[BAPilot2]

The fuel pump only comes on for a few seconds when you attempt to start it if the engine doesn't start. If the check valve goes bad, the pressure will bleed down. To see if this is the problem, all you have to do is turn the key to ON for a few seconds, then OFF. Repeat a few times and this will build the pressure back up. Then try to start.

A failing fuel pump will often work when cold then fail when hot. Then work after it cools off.

Unfortunately they eliminated the schrader test port on the later years. So to test fuel pressure, you need a test kit. You can usually get these as loaner tools at local parts store.

Thanks for the info and recommendations. It is appreciated. It is my belief that I have a fuel pump issue beginning to occur.

I know that the computers on most Mopar products are shit. I've had to replace the one on my Jeep once already. When I made my original post I thought that I may be experiencing a failing fuel pump, or a computer glitch. So, I thought that one of the forums members might chime in stating as much. I didn't know I would get berated for the use of a term that is out of vogue.

 

[Rubicon88]

As far as battery age and testing goes... the battery is good. I used a battery load tester to verify that it is holding a load and maintains cranking amps. As for the battery age it is 1.5 years old although, age is irrelevant since, it holds a load as tested with a battery load tester.

As for vapor locking... you may view it as reaching into a bag of shit, grasping for something to stick, but it can and does occur on engines. Granted, fuel pumps being installed within the fuel tank and fuel injection systems have alleviated this occurrence to the point that it is almost nil, it is not out of the realm of possibility on any internal combustion engine. I used the term "vapor locking" due to the fact that I grew up working on carbureted auto engines and also, as a pilot and flight instructor, vapor lock on a naturally aspirated aircraft engine can and does occur due to overheating. If you find fault with the terminology then so be it. Maybe I should have stated that the engine seemed like it had a problem with fuel delivery. Either way the point I was making was that it seemed to be starved for fuel.

And to address your question regarding engine swap and driving to and fro... No. No engine swap. Still factory original with approximately 116,500 miles. And, Yes! I did drive to and fro with no related problems and then it failed to start after having sat in a parking lot for the 15 minutes I was in the grocery store.

That's my point...You've done nothing. It appeared you haven't disturbed this machine. My point is that you don't just start having vapor lock by osmosis. Now if you'd messed with the lines...to replace or replace an engine and now have a different lay to them than before...got a new exhaust with a different route or dimension than before.......sure it's possible but from what I gathered you didn't do any of the sort.

My bet if your battery checked out is you've got a fuel pump issue ahead or PCM issue.

 

[BAPilot2]

That's my point...You've done nothing. It appeared you haven't disturbed this machine. My point is that you don't just start having vapor lock by osmosis. Now if you'd messed with the lines...to replace or replace an engine and now have a different lay to them than before...got a new exhaust with a different route or dimension than before.......sure it's possible but from what I gathered you didn't do any of the sort.

My bet if your battery checked out is you've got a fuel pump issue ahead or PCM issue.

Understood.
My train of thought, in consulting this forum, is that there may be some quirk or common occurrence with these Jeep’s to which I am unaware.
Obviously, it’s just the basic lack of fuel delivery.