Hard to start when hot

[sblanck]

Greetings.

I have searched this forum on the above thread and I have found that I can fix this issue if I replace this list of parts:

Starter
Battery (1 year old)
crank sensor
fuel pump
fuel sensor
radiator
gas cap
thermostat
water pump (4 years old)
entire vehicle ha ha

2004 Libby with 125k
Had tune up a year ago the whole works
Battery is a year old
yes it throws the oil sensor code but I don't see how that would affect that.
New throttle position sensor.
New A/C system

Jeep will start fine cold or cooled off for 15 minutes.
Only seems to do this when towing

Trying to make a plan of attack on which items to replace.

Suggestions?


Sean

 

[dude1116]

What does it do when it is hard to start? Does it kind of just cough to a start? Does it crank for a while?

Mine kinda just coughs to a start sometimes after wheeling or even a longer trip. My thought is that fuel pressure might not be there. Leaky injectors could be a culprit.

 

[sblanck]

What does it do when it is hard to start? Does it kind of just cough to a start? Does it crank for a while?

Mine kinda just coughs to a start sometimes after wheeling or even a longer trip. My thought is that fuel pressure might not be there. Leaky injectors could be a culprit.

No coughing initially just the nuh nuh nuh nuh sound of it trying to start.
Occasionally it will sputter and seem like its going to run and then die if I have tried to start it more than 4 times.
let it sit 15 minutes and it roars right up on start.

 

[CzarKJ]

Battery is a year old but how is your alternator? It could be drawing the battery down while driving then it takes a little but to recover.

 

[sblanck]

I will have to add that to the list.
I will check that though.

Thanks

 

[JasonJ]

this feels more like a fuel or spark related issue...

When the engine is cranking, does it ever slow down (from nuh nuh nuh, to nuh... nuh.. nuh...nuh...)?

 

[sblanck]

this feels more like a fuel or spark related issue...

When the engine is cranking, does it ever slow down (from nuh nuh nuh, to nuh... nuh.. nuh...nuh...)?

No it doesn't slow down.

 

[kage860]

Won't start when hot is a classic symptom of a bad crank position sensor on a lot of cars. Not familiar with the Liberty in particular with this issue but have seen it on other brands.

 

[teeje]

Bad injectors can do that also. Not saying that's the issue but a factor to think about


2002 Jeep Liberty 3.7L with brand new engine
Sent from my iPhone using Tapatalk

 

[kage860]

Good point, the diagnosis still needs to be done:
Off the top of my head:

check battery voltage with car shut off and with car running

check rpm when cranking the engine

check temperature gauge after a long run

check fuel pressure with the car running and check for leak down after you turn off the engine

 

[belvedere]

Test your fuel pressure.

 

[JasonJ]

I asked if the cranking speed slows down because, that part can be indicative of a weak or low battery, as well as a high drain, faulty starter. While I'd still put a meter on those, they likely aren't the cause.

I'd test fuel pressure, if it is not within spec, look at the pump/relay circuit. Make sure it is getting proper voltage. if not, troubleshoot down that route.

 

[vaksanov]

When I changed my fuel filter with an advance auto parts one it was doing the same, once it warmed up it wouldn't start back over. Warm it up, and if it doesn't start, try the starting fluid, if it starts then it's your pump, get the whole kit from the dealer and you should be good.

 

[JackieRedShoes]

Same thing happens to my 05 KJ, along with an intermittent CEL misfire cylinder 2. After replacing the plugs and coils the code still comes back and it won't start occasionally when hot. I suspected bad or clogged injectors because the CEL would come on like clockwork if I sat with the engine running in park for too long, so I put in injector cleaner/fuel treatment every time I filled up (after driving till the gas light came on) for a while and it helped both problems.

 

[E.W.G.]

This happens to me as well, 2004 Liberty 3.7l, and it's maddening. Typically only after a quick stop, like to run into Tim Horton's, it has a slow crank as if the battery is low but the headlights stay strong and no codes are thrown. Sometimes with a few turns of the key it cranks right over as if normal, other times it just stops cranking altogether. It seems that cold weather makes it more frequent. I am debating replacing the starter but I don't want to just throw parts at it.

 

[fastcarsspeed]

I would start with the following.

1. use some Carb Cleaner and spray some cleaner int he throttle body when this happens. (If she starts then you have a fuel issue).
2. Next would be to check to make sure you have spark.
2. I have heard of issues with the Crank Position Sensor acting goofy after it warms up so if the cleaner does not get it to start I would possibly look at that.