Weird starting issue

[Macdaddy]

02 Liberty 3.7....just bought this liberty sport....it has ran and started well til just a few days ago....it has suddenly become iffy on starting....no codes....if I do short start bursts it will eventually sputter a couple times and then start...it seems to labor a little ramping up to idle....so far after starting it runs fine...any thoughts? I did replace the crank sensor...engine was tuned before I bought it....plugs, air filter.etc...130,000 miles

 

[ltd02]

Did you use a Mopar crank sensor? What type plugs were used? Fuel pressure OK?

My 02 has always been a bit sluggish to start when warm, but it always does start.

 

[J33Pfan]

aww first post!

Welcome!

do you think the car was laid up and the gas is stale?

was the gas tank 1/4 or 3/4 full when you had this problem starting?

why did you replace the crank sensor?

 

[Macdaddy]

Yes...mopar sensor...Bosch plugs...didn't check fuel pressure yet

 

[Macdaddy]

Actually owned it now 3 weeks....probably 10th tank of fuel....

 

[Macdaddy]

Probably half full of fuel...did some searching....seemed to be a common issue....didn't change anything for me

 

[J33Pfan]

fuel pressure is important at first start. you have to hear the pump come on when you turn the key and let it pump before you start it.

do check the fuel pump pressure ASAP!

people here only suggest NGK v groove or copper spark plugs. I would switch to one of them as well.

 

[ltd02]

Like I said, mine's always started "weakly" when warm. Seemed like it was going to stall everytime. I bought it with about 80k on it and did this for the past 10 years and almost 100k. I was worried about it for a bit but heard other complain about the same thing.

I ran Bosch +4 Plats for about 40k shortly after getting my KJ. Ran okay but runs better with the coppers.

 

[Macdaddy]

Will do...will check pressure and switch plugs...I do let pump run before turning key to start...not sure if pumps running enough...hear a short noise then silent...any idea on decent pressure numbers

 

[Macdaddy]

I guess it may have been first time I tried to start it shortly after shutting off...usually it sits for quite awhile til next start....may be a little vapor lock...sounds like maybe a characteristic of these motors

 

[ltd02]

I really notice it when I stop for gas. Happen every time then.

 

[Macdaddy]

I'll check fuel pressure and see how it goes.....seems to run good otherwise just makes me nervous to coax an injected engine to start occasionally. ..lol

 

[Macdaddy]

Yep that's when it happened...gas stop

 

[Macdaddy]

Thanks for the insight

 

[J33Pfan]

I guess it may have been first time I tried to start it shortly after shutting off...usually it sits for quite awhile til next start....may be a little vapor lock...sounds like maybe a characteristic of these motors

i thought it had to be really hot out for a vapor lock

what brand of fuel and what octane do you use?

 

[Macdaddy]

Just the engine heat can cause it, under insulated fuel lines near hot junctions can produce pockets of vaporized fuel,not saying this is case here, but sure acts like it...shuttng off engine and then trying quick restart can make it show, worse during hot weather....always use best available fuel ,we have numerous convenience stores here, not alot of branded stations, always the threat of bad fuel try to avoid dumpy places or when the tanker is there remixing the water and sediment in underground tanks