Jeep XJ long crank, fuel check valve fix. -
  • 1 Post By edrrt
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post #1 of 4 Old 02-12-2020, 02:08 PM Thread Starter
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So I like many others finally developed a long crank on my 99 Cherokee XJ. No surprise given the age of the vehicle and it's a common problem related to the fuel check valve gumming up. I rented the fuel line pressure tester for free from the local auto parts store and confirmed that the pump was pressurizing but then losing pressure as soon priming was finished.

I was getting prepared to undertake that major tear down when I read Reports online about seafoam. There's a lot of debate on what it does however people seemed to agree that the one place that it does work is fixing stuck check valves when put in the gas tank.

So I decided to try it and it actually did work. After 2 cans I started to notice a difference.

By the fourth can and tank of gasoline the problem was resolved. It was starting on the first crank. And it has continued to do so for the last year. I have seen some people report as many as eight cans are required but for me 3 to 4 was the magic number. Regardless it's still significantly better than tearing the car part.

So I'm just posting this to give the thumbs-up to seafoam in the gas tank for fixing the check valve on an XJ.

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post #2 of 4 Old 02-13-2020, 06:52 AM
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Well thanks for the idea. are you doing this one cane after the next? I will try this in mine which has a replacement Bosch that has started to loose pressure overnite.

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post #3 of 4 Old 02-15-2020, 09:31 PM Thread Starter
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Good question. The short answer is idk what's best. I reasoned the longer the seafoam solvents stayed in contact with the valve the better. And the more concentrated the better. I added a full can to about a half tank to make it very concentrated at a time when the car was not going to be driven much. Took maybe a week to empty the tank. Then if I needed to do a long drive I would wait until I would a low fuel consumption week, then drop a can in a full tank, and take a week to work through it. I figure if I added it and burned it right away it would have less time to work on the check valve. Small trips rather than a 4h drive.

No changes until the third can was done. Maybe 3 weeks in. Then I noticed it started holding pressure. But if left longer than a few hours would still get along crank. So it was starting to loosen. 4th can, 4th week... I forgot all about it cuz the problem resolved and never came back.

I only thought of it today because working on my WJ I found the other 4 full cans I had bought for this but didn't end up needing.

I am not a believer in all things they claim seafoam does. The data is lacking. But I did note researching the check valve issue across Google there were a number of first hand reports of success for that issue. So for 20 bucks why not try.

Then I had a Honda ATV that would not idle without choke because the gas got old and plugged the carb jet. Everyone says... gotta tare it down. Well I threw a can of seafoam in it and it fixed it. Unbelievably.

So I think it does work in fuel to dissolve the deposits that mess with the fuel system components.

My snow blower I used to have to dump last years gas, my Honda wouldn't run it at the start of every season. Now after adding it to the fuel at the end of the winter... starts next winter first pull on the old gas.

So based on my N of 3 for those applications... it is not snake oil.
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post #4 of 4 Old 02-21-2020, 03:01 AM
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I think one cane after the next should work, right? What's the harm in it, after all?
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