Have to start the TJ twice

Lowcountryearl

Lowcountryearl

TJ Enthusiast
Joined
Jul 20, 2020
Messages
129
Location
Charleston SC
Kinda racking my brain on this problem. Starts fine in the morning first crank regardless if it's hot outside, cold outside, raining, no issues.
Drive it around for a while, park it and go in the store for a couple of minutes, come out and it will eventually start but only after about 5-7 seconds. If I come out and give it a very short first crank, it will start right up with the second crank, doesn't matter how long or short the first crank is, it starts almost immediately on the second crank. New AGM battery, all new tune-up parts, wires, plugs, cap etc. I know of a service bulletin for wrapping injector 3 with heat shield for the newer 4.0, mine's a 98, does'n say mine engine is affected. Appreciate the help!
 
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Funny you post this...I’ve been thinking about this this week. Rubicon 2006 35k serviced up to date and I experience the thing. Short crank then always immediately fires up on second try.

So, this is how I’ve discovered to get around this...not technical I’m sure but does ensure it starts 1st crank immediately.
Cold...turn key to ign on , wait about 15 to 30 secs then crank and it fires up. When warm mine just fires up all time. Seems a slight pause at the ign on before cranking does the job.
Ps reason I was on this this week is that I’ve just taken mine back out of storage and over last month gone thru the whole thing.
 
Could be the cold start is using an open loop setting in the computer. Once the engine is up to temp it switches to a closed loop system. Meaning the fuel is now controlled from the O2 sensor readings. A questionable set of O2's may not throw a code, but be enough to cause a restart problem when conditions are marginal as to whether to be in open- or closed- loop settings.
 
Have you tried turning the key to the on position for a few seconds before trying to actually start it every time? My 98' had a leaky anti drainback valve. My 03' had a CPS going bad that caused a similar problem.
 
Sometimes I go to turn over my engine, and same issue. Potentially the first crank is letting your fuel pump send fuel to the injectors, and second crank is it firing, because the now primed injectors have steady supply? Any other thoughts?
 
I have tried the turn the key on and let sit for 5-10 seconds, doesn't make a difference. I have also tried turning the key to the on position, off position and then let it sit and that sometime helps it start faster on the second crank. I think if was a check valve or drain back into the fuel tank it would not start in the morning. Trying to digest what Goatman said, seems logical
 
You need to get fuel pressure readings to eliminate or confirm some things.

The cold start reading when it seems to act normal.

The warm start reading when it's acting strange.

Not saying you're guilty of this but so many posters come on here and will literally throw parts at their Jeep refusing to buy a lifetime tool like a fuel pressure gauge.
A tool will help so much in telling you what is going on with the fuel system which obviously is essential to the combustion emgine car. Moreover I promise you'll use that gauge again in life.

Before anything else including driving yourself mad...check those pressure readings.
 
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I've got the same issue. Long start, or won't start until second try. Even replaced the fuel pump because I thought it was the check valve gone bad, but the issue's still there.
 
If you are able to fire right up when cold start then it would seem to me that your fuel system is working correctly. That is when it has plenty of time to bleed down fuel pressure.
I'm unsure how it could lose pressure in 10 minutes but build pressure back up if it sits overnight.
That is what makes me think that it is some sort of conflict between the open loop and closed loop settings when the engine has gotten to half-cool.
 
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Goatman said:
If you are able to fire right up when cold start then it would seem to me that your fuel system is working correctly. That is when it has plenty of time to bleed down fuel pressure.
I'm unsure how it could lose pressure in 10 minutes but build pressure back up if it sits overnight.
That is what makes me think that it is some sort of conflict between the open loop and closed loop settings when the engine has gotten to half-cool.
Click to expand...
Unless he has a slight leak, or getting vapor locked...
Weak pump after running for a time...
Many possibilities here and certainly can be something fuel related.
The o2 may be bad alright but won't cause the no start being experienced.

I still suggest a fuel pressure gauge here. #1 it can quickly confirm psi reading is where it should be in both easy start and hard start situations...#2 a 40 dollar tool that can be used for a lifetime is a great investment. Especially having the ability to confirm some things at present on said good start/hard start situation and a tool that I'm certain will be used again...and again.

This thing needs a psi reading before cranking when cold (when the OP knows it will start proper) and it also needs a psi reading before cranking (when the OP thinks it will start hard)

To the OP statement of a TSB on wrapping cylinder #3 and not being affected because it's not in the same year as the TSB listed...

Don't "assume" anything...
Not long ago we replaced a wiring harness on a Town and Country where the fuel pump would not shut off ...even with the ignition off and key out.
Chrysler had a TSB on this and this vehicle wasn't even close to the year window listed. Yet had the same exact symptoms and got the same exact fix.

The point is right now don't assume anything until you can properly diagnose some things and start ruling out or confirming. Until then it's throwing shit at the wall and hoping something sticks.
 
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Lowcountryearl said:
Sure, can you recommend a decent one at a decent price that will come with the proper adapter?
Just
Empty
Every
Pocket
:)
Click to expand...
You should have a standard 1/4 ' schrader port on your fuel rail and pressure test kits are usually available as loaners from auto parts stores. Get your pressure readings as Rubi88 suggested.
 
So, second day where I’ve done this. Turn ign on don’t crank....depress accelerator 3 times, gently and not even to floor. Crank engine and it starts 1st time. Seems this work around works until we diagnose really what’s needed.
Good luck.
 
Ok, bought the fuel pressure gauge and when the engine starts immediately goes to 50 psi
When I shut the engine off, it immediately goes to zero.
Should it hold pressure?
 
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