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Old 05-23-2018, 06:24 PM
Thread Starter
Join Date: May 2018
Location: Southern Ontario, Canada
Posts: 2
Labored 4.0L engine start...

Hey there, so I'm wondering if anyone has light they could shine on a strange situation I'm having? I've got a 2003 Rubicon which I bought brand new waaay back now. It has 126Kms on it (or about 75000miles) it is stored winters in my garage and I use a "battery tender" brand charger on an Optima red top battery.
I start the Jeep about every 2 weeks and run it for 15-20 mins.
However, I've had to replace the battery and I also put a brand new starter on it.
I also have a battery run down preventer on it.
I am experiencing very laboured starts, to the point of it barely starting and sometimes not at all. I'm getting gauge needle bouncing during starting attempts and a rough idle for the first few seconds requiring throttle play to keep it going. Afterwards it seems to drive fine and idle well until I shut it off and the whole procedure repeats itself. Also, I've experienced a laboured start as above and had the engine start, but then immediately stall (about 1 second later), then the second attempt requires throttle play.
I have no check engine light on and have to add the Jeep has always been very well maintained is in far above average condition.

I'm puzzled...

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Old 05-23-2018, 11:07 PM   #2
foco's Avatar
Join Date: Oct 2014
Location: Colorado
Posts: 705
It's possible there is a bad check valve in the fuel pump, allowing the fuel to drain out of the fuel line and back into the tank.

The test for this is to turn the key on (don't crank) for 5 seconds, then turn it off. Repeat that 3 times. This will pressurize the fuel line. After doing this 3 times, try cranking and see if it starts any easier.

David LeDeaux
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Old 05-24-2018, 09:37 AM   #3
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Join Date: Jul 2016
Location: CharlottesHELL, Va
Posts: 2,494
Have the battery and alt checked. It's free. Mine did the same thing when I had a bad battery.
03' Rubicon/Zone 4.25" combo lift/Rancho 9000XL shocks/5.13 gears-35" MTZs/LoD bumpers/Black Magic brakes
99' XJ under construction/ 5.5" lift/ Rancho rs5000x shocks/HP30-8.25/ 33" DC MTs. (JEEP #18).
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Old 05-24-2018, 11:02 AM   #4
Join Date: Apr 2014
Location: Lakeland, Fl/ Glenville, NC
Posts: 57
X2 on the battery test. Mine was doing the same thing. Tested battery good so I replaced the starter and solenoid. Same problem. Retested battery with a load and discovered bad battery. Replaced battery and everything is fine.
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Old 05-24-2018, 12:15 PM   #5
Join Date: Apr 2013
Posts: 13,239
Does lobored mean slow crank or prolonged rapid crank without engine start

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Old 05-25-2018, 01:08 PM
Thread Starter
Join Date: May 2018
Location: Southern Ontario, Canada
Posts: 2
Thanks for the input guys.

By "laboured" starts, I'm talking difficulty in the engine starting with slow, tired cranks, NOT a fast continual cranking with no firing.

I was having this problem for a couple of months (while the Jeep was stored in my garage) and I bought a brand new Optima red top battery and then even put a brand new starter on it, thinking maybe the starter or solenoid was bad.

Also, I keep a "Battery Tender" digital charger on it, so there's always the appropriate amount of charge going to it when its not in use.

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Old 05-25-2018, 07:46 PM   #7
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Join Date: Apr 2016
Location: NB, Canada
Posts: 177
I would load test that new battery like others have said. Might have a dead cell from the factory. What you describing sounds like a weak battery.

If battery is fine you may have corrosion in the starter lead causing voltage drop across the starter circuit.

2003 TJ Sport 5 speed - 4" SL, 1.25" BL, 35's, 5.13 gears, Rubi D44 w/Stock Locker+LS, HP30 w/Spartan
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hard starting

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