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Discussion Starter #1
hi guys :)

I noticed my cold starts getting harder sometimes, like 4 sec crank.

my hot starts are always good.


is this an o2 sensor going bad?

I have no codes.

the engine is running great otherwise!!! plenty of power.

im pushing 173k miles :)


im an o2 sensor noob.

upstream is by the engine?, looks like u need to be a contortionist to reach them.

:whacky::whacky:
 

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Discussion Starter #2
short list:

plugs are ok just replaced them. champions, ran the stock plug all the time.


could be:

fuel rail or something weird like that?
upstream o2?
crank sensor or something like that?
timing chain (I don't wanna think about that hahaha). ??? maybe not. running great when hot plenty of power, no knocking etc.

for some reason im thinking o2 sensor but need experts to chime up on this one.
 

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Discussion Starter #3
fuel pressure regulator on top of pump on tank (@#@#)

or o2 upstream going bad?

I think im narrowing it down by symptoms to possibly one of the two above.
 

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Discussion Starter #4
found this from another post,

fuel pressure test kit

https://www.amazon.com/gp/product/images/B0009XQUKC/ref=dp_image_0?ie=UTF8&n=15684181&s=automotive&tag=viglink20919-20

$60 cheap !!!


however, free procedure is to turn the key without starting and let the pump prime, and see if it does it when cold.

if it doesn't, then probably a fuel rail issue hmmm leaking down from the FPR.

im wondering how hard it is to drop the tank.


I remember dropping the tank on my old corvette and it was a PITA, sawed off exhaust and it landed on my chest and ouch. lol :)

hopefully jeeps are easier to drop the tank on :)


is fuel pressure regulator easy to replace?

is tank easy to drop?

ok a bit preemptive of me.

ill do some more troubleshooting first.
 

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Discussion Starter #5
...adding IAC to check.

TPS is fine, replaces a little while ago.
probably not crank sensor...

which leaves me with the list:

upstream o2
IAC
FPR

ok IAC was on my bucket list to clean anyways lol....
 

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Sounds exactly like your fuel pump assembly has a leaking check valve allowing the fuel to leak down out of the fuel rail and back into the gas tank. That it drains out enough so the engine won't start until after an extended cranking time happens when the Jeep has been sitting an extended period of time.

The extended cranking time required to start the engine after it has been sitting an extended period of time is how long it takes the fuel pump to get fuel back up to the fuel rail.

To verify a fuel pump issue, cycle the ignition switch on-off-on a dozen times pausing a second each time the ignition switch is in its On (not Start) position. If it then starts immediately after cycling it a dozen times, that confirms the problem is the fuel pump assembly.

If you decide to replace the fuel pump, go only for a Bosch like can be found on Amazon.com. Avoid store brands, or online brands like Airtex or Spectre. None of those will hold up long enough to be worth installing.
 

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Discussion Starter #8
its an 02 TJ 2.0 L

thanks jerry, ill try the free test and see if it confirms.

then ill get a pressure gauge and check the rail (im a numbers guy).....


watched some youtube vidz and looks pretty easy.

never liked playing with fuel though lol :) but looks easy.

tnx all
 
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