4.0 Help

[RockChucker]

I have a TJ with a 4.0 and the engine runs great, but it is hard starting. it cranks and cranks. it usually takes 10-15 seconds of cranking in a couple bursts. i'm thinking it has a little bit low compression. could that cause this? i only suspect this because it will not hold my jeep on my driveway when it is in gear and parked. my driveway isn't super steep either. any thoughts? i have thought cps and what not, but from what i understand that won't let it start at all...and once again, once running it runs fine, but it does kill easier than it used to.

oh and i did a cap and rotor and plugs not too long ago thinking that would help. no go.

thanks

 

[jmaxj]

check the voltage on the TPS, if its off it'll give it hard starts.

 

[Cherokeester]

Could be: Tps voltage as mentioned, low fuel pressure, O2 sensor failure or problems. I would start with those.

 

[astjp2]

Turn the key to ON, 3 times, then try to start it on the fourth, If it starts immediately, its the fuel pump or filter is having issues. Tim

 

[RockChucker]

alright, thanks for the suggestions. i have made further progress on finding potential issues. my cat is going bad. it is starting to rattle, and i think it is partially clogging the exhaust, causing the o2 to read wrong, and it now is running rich. so i'm going to start by replacing that and go from there.

 

[gorillaxj]

sounds like the fuel check valve is leaking the fuel back into the tank, so when you go to start it up it has to build pressure in the system taking a while to start.

 

[RockChucker]

sounds like the fuel check valve is leaking the fuel back into the tank, so when you go to start it up it has to build pressure in the system taking a while to start.

that may be a possibility, but if that was the case, wouldn't it help to just turn the key on for a second before cranking? if that would work, it doesn't help.

 

[iamsparticus]

does any lights come on the dash? if its the evap system or pressure in the tank it should trigger a engine light but usually that can be caused by not clicking the gass cap enough times or a leaky seal where the cap goes on or any sending units in the tank

 

[RockChucker]

No dash lights. That is why it is so frustrating.