2003 TJ died while driving, now cranks, but won't start

k0m0d067

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Jun 9, 2019
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120
Location
Victoria Australia
Everything was going just great (other than an occasional weird high idle/idling surge) when my Jeep died in the McDonald's drive thru...it idled REALLY rough/weak for maybe 30 seconds before it died, which led me to think fuel pump? So I called roadside assistance, and got towed home...

Now it cranks like a champ, but doesn't fire...I can hear the fuel pump when I turn the key, and it stops after a couple seconds...nothing out of the ordinary...bought a pressure tester, only to find out my 03 doesn't have the schrader valve...so I guess I will have to make a test hose, to go somewhere before the fuel rail to test the pressure...

From what I'm reading, crank position sensor is a possibility too? How can I test this?

Now, for the weirdness:

In the picture I'm attaching, what is the item in red (sorry if it's a stupid question...appears to be a vacuum manifold of some sort)? it has an electrical connector which hasn't been connected, possibly since I got the Jeep, but definitely for 2 years...I looked around and believe I've found the plug for it, but obviously this wasn't what was causing the problem, since it's been disconnected for ages

Also, there was a vacuum line that looks like it should have been connected to the intake manifold in the location indicated in yellow...it's the one furthest toward the front of the car, connected to a steel line, that appears to run towards the back, with the fuel lines...again, this looks like it's been disconnected for a while...

TJ engine.jpg
 
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k0m0d067

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Jun 9, 2019
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120
Location
Victoria Australia
what size is the fuel line connector at the rail? I need to buy the fittings to make a test loop, and I don't want to waste time buying the wrong ones
 

Mall'er

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May 3, 2021
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96
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Portland
What is the availability of other 4.0s in your area? You can swap the fuel rail from a cherokee or grand cherokee that has the schrader valve. I swapped the rail on my 04 just to get the valve.
 
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DETOUR

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Dec 24, 2018
Messages
683
Location
British Columbia / CANADA
In my case , ‘05 LJ, TPS ( throttle position sensor) was acting up, with similar scenario . Approximately every 50’000 km ( no check engine light, no codes ). I got a spare TPS in my toolkit 😊

🚧DETOUR👋🏿🚧
 
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k0m0d067

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Jun 9, 2019
Messages
120
Location
Victoria Australia
Nothing readily available...occasionally you can find someone parting one out, or there are a couple wreckers a couple hours away that specialize in tj's...but this is my daily so can't drive the 2 hours to go get something...

I've just ordered a couple fittings, so hopefully that will let me test the pressure
 

CharlesHS

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Mar 10, 2020
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Jacksonville FL, Quezon Philippines
There are three vacuum lines connections on the intake manifold; 1st supplies the Vapor Purge Valve, 2nd supplies to the Purge Solenoid and 3rd supplies the Vacuum Reservoir beneath the battery tray, the A/C Climate Controls and the Cruise Control Actuator (if equipped).
You can test the CPS using the video below.

 
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JPHikr

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Jun 27, 2020
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344
Location
East of Nowhere Airzona
This is why it is good to carry a can of starter fluid. A quick spray in the air box will tell you if its a fuel problem or electrical to the fuel pump. If it is a fuel problem clean the block ground by the battery first. This will ensure you have a good ground.
 
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Jim B

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Feb 6, 2018
Messages
61
Location
Kingman, AZ, USA
I had the same problem a year ago. After towing it home it started normal and had been perfect ever since.
Had a local shop (with a lot of Jeep experience) check it out and they couldn't find anything wrong.
 
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