Jeep YJ LS swap problem
Thread Starter
Teching In
Joined: Dec 2015
Posts: 48
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From: WI
OK I have it solved. A massive amount of water in the fuel tank. I siphoned about 12-15 gallons of fuel from the tank before replacing the pump/sending unit into 3 gas cans. We did dump the gas tank out after removal. After replacing the module I dumped 2 of the gas cans into our daily drivers with no problems. I poured the last one into the YJ and had the same problems. I must have been unlucky enough to save the can with the water and used it. Yesterday I unhooked the fuel line to the fuel rail and hit the key a few times to pump out about a pint or so and a considerable amount of water was in the bottom of the jug. I then added about 4 gallons of fresh premium (no ethanol) and a pint of isopropyl alcohol. Then I went and pumped another 9 gallons of premium with another quart of isopropyl alcohol. It now runs very well. I still notice a slight hesitation on acceleration at times but at least now we can drive it during the summer and appreciate it while we can because it sits during the winter. I blame it on a local gas station. 2 months of prime summer driving lost. The symptoms were jerky engine operation, engine dying, backfiring, engine would stumble like it was dead then then take off abruptly. I hope this helps someone.
Thread Starter
Teching In
Joined: Dec 2015
Posts: 48
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From: WI
I AM WRONG. It ran very well on Friday. Saturday started out OK then it started dying and finally quit and would fire but not stay running. I towed it back today and it did start and ran but I only ran it for a short time. Back to the drawing board.
Thread Starter
Teching In
Joined: Dec 2015
Posts: 48
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From: WI
OK I replaced the bank 2 O2 sensor. WOW it runs better than it has for quite a bit. I will keep YA'LL updated. I do have 2 AC/Delco matching O2 sensors on the way and will install them when received. The LS Jeep runs the best it has now.
Thread Starter
Teching In
Joined: Dec 2015
Posts: 48
Likes: 0
From: WI
Hey there. For about 2 + months I have had a problem. Shortly after getting it out of the garage from the winter. At first I felt a slight surging going up a grade. Then it would chug, and or do the herky jerky, or just stall then go or just plain DIE. I replaced the parts listed to no avail.
Fuel pump and sending unit which I wanted to do along with the associated fuel lines since the LS upgrade.
Fuel filter "again".
Fuel regulator
crank sensor and cam sensor.
Checked fuel relays
MAF sensor
Finally I replaced the O2 sensor on bank 2 with the help of one of my friends help to diagnose it. I lost 2+ months of enjoying the Jeep with my wife and myself using the Jeep this summer. I tried to do it myself but in retrospect I should have asked for help earlier. It runs better now than what it was before, I believe.
The learning thing is look to the O2 sensors as a possible problem. My codes only showed 1 sensor as a heater problem but as it was the problem was a faulty O2 sensor and it caused the above problems or symptoms.
Fuel pump and sending unit which I wanted to do along with the associated fuel lines since the LS upgrade.
Fuel filter "again".
Fuel regulator
crank sensor and cam sensor.
Checked fuel relays
MAF sensor
Finally I replaced the O2 sensor on bank 2 with the help of one of my friends help to diagnose it. I lost 2+ months of enjoying the Jeep with my wife and myself using the Jeep this summer. I tried to do it myself but in retrospect I should have asked for help earlier. It runs better now than what it was before, I believe.
The learning thing is look to the O2 sensors as a possible problem. My codes only showed 1 sensor as a heater problem but as it was the problem was a faulty O2 sensor and it caused the above problems or symptoms.
