Trouble Starting When Warm

[frontrangecctv]

Hello fellow KJ owners. I am rather new here so please let me know if I am doing anything wrong but I am having an issue starting/re-starting an already warm engine on a 2006 3.7L Liberty with 134,000 miles

Over the past few years, now occurring more often, my KJ has had trouble starting after it has already warmed up. For example, I can start it fine after it has been sitting for several hours but if I run to the store, turn the engine off, then return 10 minutes later, the engine has trouble starting. It cranks just fine and after about 4-5 crank attempts, it will finally start, run rough for about 20 seconds, then run normal like nothing happened. No check engine light or codes.

This problem started about 2 years ago but would only happen 3-4 times a year. Now it happens about 2 time a week. The engine doesn't overheat and has a new water pump and thermostat that was installed last year.

Any help or advice would be SUPER APPRECIATED!!!

 

[02redKJ]

My first thought was that it was a hot starter or solenoid. But if it is cranking, not so clear cut. Does it crank as fast as it does when it is cold? Does it sound about the same when cranking cold as it does hot?

I'm not sure about the rough idle at first ignition when hot though. May be something with the computer idle setting. No codes though? Strange. How old is your battery?

Maybe someone else can come along and help.

 

[Luke]

Your not alone ... it has only happened to me 3 or 4 times in 4 years... but several of us have had it happen.

I'll see if I can dig up the old thread, not that there was a resolution.

 

[02blue]

My 02 (160k) does it all the time when warm. Sounds like the same as your description. It's done it for three or four years.

It always starts, so when it doesn't start at all is when I'll worry about it.

 

[Luke]

Here are a few ...

http://www.jeepkj.com/forum/f196/strange-intermittent-startup-issue-52427/

http://www.jeepkj.com/forum/f196/hot-engine-starting-problem-54336/

 

[02redKJ]

Another thought... I had an issue back in the 80's when I souped up my Ford F250 460 engine. When I put my headers on I ran them too close to the fuel line AND the starter. I had to wrap the header to cool the starter, and that helped, but what ultimately fixed the problem was re-routing the fuel line. I guess the line was getting too hot and was vaporizing the gas before it got to the carb. You could trace the fuel line and see if it is close to anything that gets hot.

Also, think about this... running the engine warm and only driving a few miles does not give ambient air enough time to cool as if you were driving at highway speeds for an extended time. Just throwing out suggestions. Hope it helped. I know I pulled my hair out for months before I figured out what it was. And it was BOTH problems at once when it was the worst.

 

[Luke]

Yes, it acts just like "vapor lock" ... but I thought that kinda thing was limited to older generations of engines :shrug:

 

[02redKJ]

Well gasoline is still liquid and can still turn to vapor if heated. Granted the engines have changed drastically over the years, but the go juice has remained relatively the same, barring additives etc... Some geographic locations have different additives based on what time of the year it is. Maybe some of the additives raise or lower the temp that causes the fuel to change from liquid to vapor. Which may explain why it only happens part of the year.

 

[CactusJacked]

Yes, vapor lock is for the most part a thing of the past. Old cars or trucks didn't have a fuel return line to the tank like modern cars do, which keeps the fuel circulating and in turn, cooler.
Yours could be a few things, and what you're describing sounds like a flooded engine. Try putting a fuel pressure gauge at the fuel rail, and see if pressure holds for a bit after you shut the engine off. If pressure drops fast, you have a leak. One possibility could be a leaky injector, flooding a cylinder. After a short stop, that's enough to flood the engine enough to make for a hard start. But overnight gives the gas time to dissipate.

 

[frontrangecctv]

Thanks for all the help guys and thank for the links to the other threads. A few things I forgot to mention:
1. I also have the overflowing gas tank problem (pump at the gas station doesnt shut off on time and fuel spills when refueling) Not sure if this would be related.
2. I live in Colorado and know they add more ethanol to the fuel here during the winter however I have had this problem happen during the summer as well so i don't think its the actual fuel.
3. Whether it is cold or warm the engine cranks normally, albeit a bit harder when its cold but ALWAYS starts right up when cold. it has a factory block heater installed but i only use it when its below 30.
3. I can be driving for 2 hours then stop for 10 minutes, and the problem still happens, so short/long trips don't appear to make a difference. Usually after sitting 30 minutes it will start right up. Its really anything from 5-20 minutes where it doesn't want to start right away.
5. The injectors are still the factory injectors, so it may be way past due to replace. I like the theory of a leaky injector.
5. Battery is good but old. Cold cranks ok but probably due for a replacement too.

I think ill start with the injectors and battery. Never changed injectors before but I assume its not too difficult but if anyone knows of a walk through or where to direct me to that would be great!

 

[CactusJacked]

Injector(s) is only one possibility. On the other end of the spectrum, you could have a fuel starvation issue, where the fuel pump could be going south and overheating as it runs longer, then gets temperamental at a short rest restart. Again, check your fuel pressure first, before you start throwing parts at it. Write down what your pressure is all three ways; key on (initial prime), engine running, and with the key off/how long it holds. Do that both with a cold engine start and with a hot engine restart.

 

[frontrangecctv]

Thanks CactusJacked. I will start with a pressure gauge. I also thought about checking the spark plugs as they are easy to get to. Maybe just a fouled plug or two. Also something else i noticed. It only seems to have problem starting when the fuel is below 1/2 tank. Not sure if its related or just coincidence.

 

[frontrangecctv]

UPDATE: Today I had the problem happen again, this time as it was stumbling to get started/rough idle, the check engine light started flashing and flashed on/off for about 10 seconds. After 10 seconds it started idling fine and the check engine light stopped flashing and turned off? Is there a way to pull codes if the light is off? Would it be a "pending" code still stored in the computer? Does anyone know what a flashing check engine light means?

 

[Luke]

Is there a way to pull codes if the light is off?

yes .. key on/off/on/off/on ... for some KJ's. It shows up in the Odo display

I'm curious to know what code you got!

Flashing CEL could be a million things .. most importantly it means "check me out NOW" ... I would not drive it far.

Edit: From what I just read ... it may not store the code if the CEL was flashing and not solid :shrug:

 

[CactusJacked]

The CEL on means it would be a good idea to check it as soon as you can.
A flashing CEL is more serious and means get it checked NOW.

 

[Snail Farmer]

The flashing CEL I believe means something is going on that will damage the cats.

Sent from my HTC One using the power of Mary's purse

 

[frontrangecctv]

Tried the on/off key dance....no dice. Tried the key on while holding the trip reset...dash and gauges went through a fancy test, but still no codes. Took it to Napa, no codes stored. Let it sit turned off for about 10 minutes, went to start it to try and reproduce the code with the reader attached.... No luck, it just started right up like nothing's wrong.

When it did come on earlier today it came on about 5 seconds after the engine barely started and was stumbling. It did not stay on steady, it just flashed for about 10 seconds then once the engine started idling normally, it stopped flashing and turned off. I've heard a flashing MIL means a severe misfire, but could also mean a multitude of other things.....I'm at a loss here.

 

[4thefam]

I have the exact same problem. Here's what I know. I have 170K on my 05 Liberty 3.7L. Last year it started over heating on me. I replaced the water pump and took it out for a test drive. Still hot hot and I pulled over to sit and let it cool. Cooled down to midrange on the gauge and I tried to start but would not. Stumbled and cranked but no joy. It reminded me of a vapor lock and the fuel rail was very hot to the touch so I took off the schrader cap, wrapped a rag on it and let a burst of pressure off. Damn thing fired right up! Ended up having a bad radiator btw. And I think its leaking from the head gasket but not sure how to test for that.
Anyway, a year later and it does it again only this time no overheating issue. Just stumbles on crank and wont start. I thought bad gas but remembered the pressure valve trick so I tried it again. Same result! Let off some pressure and it fired right up. SO now I'm thinking I needing to check the fuel rail pressures like mentioned earlier in this post and see if there are changes. I can't help but think its all related to the over heating issue and the possible head gasket leak. I did get a steady CEL and the code was a number 6 misfire so the leaky injector thing might be happening too.

 

[KJordan333]

Not sure if my novice input helps, it's just more evidence I suppose.

Ever since I got my 05 3.7 KJ it's had random hot start problems. No more than once every 2 months in the summer never in the winter. I always start it with a little bit of gas if it doesn't want to start and it fires up and runs perfectly. Like everyone else, it happens after driving then a short break. Itll crank but not fire up. I heard a good spot to start is fuel pressure, but since a check costs $150 and it's never actually not started entirely (fingers crossed), I just leave it alone... hopefully there'll be a final workaround someday.

 

[TomG]

I've been following a lot of the threads regarding the liberty "hot start" issue. For the past couple years, I've had this problem after towing or crawling through some difficult terrain (2010 jeep liberty, 185,000km). It would always start after 5-10 minutes but its always disconcerting when you're out in the bush. I was getting the the point of trying to check the various pressures in the fuel system or pulling the plugs as some have mentioned (not a mechanic but somewhat mechanically inclined), but I have come across a potential simple fix/issue that has so far been working for my rig. As mentioned in another thread, I've reset the PCM (runs a little smoother now especially at start), but I also noticed that metal coil that wraps a pipe (what I'm assuming is a part of the fuel system and is wicked hot after towing) going into the manifold above the EFI had slid down. In regard to all the comments above about potential vapor lock (if it actually has something to do with the fuel system), I slid the coil back up to where I thought it should be (pictures of it after moving it back up) and I haven't had an issue since. I'm assuming this is way to simple of a "fix" for all of the hot starting issues out there, but hopefully it'll help with a few....