Need ya'lls help - please.

Short story.

Took Jeep to emissions. It passed no problem. Except for one things, it failed pressure test. That is where they pressurize fuel line and see if it holds pressure.

Took it to SSC automotive on Power and Williams Field. They told me two things.

1) The leak is coming from the top of the gas tank.
My question is, what if anything is on the top of the gas tank? I've never had it out so I don't know.

2) This is the big one. They told me that the compression in my #1 cylinder is at 75psi and one more cylinder has low pressure too. What is weird is that it runs very good and passes emissions.

I'm not letting them do anything else and I'm picking it up. So can you guys help? Have any of you ever had your gas tank out? What is on top? Any grommets? Any valves?

Second, what am I looking at to do the valve work? I have been wanting to rebuild an engine, (not out of necessity though) maybe now is the time. Thanks for any input.

Don't know about valve work but try replacing the gas cap as fuel injected XJ's have a pressurized tank and I'm willing to bet that is where the leak is.

Yeah, The gas cap would be the first thing, look at your old one to see if the seal has any cracks. There are gaskets on the tank where the sender and some hoses go into it but I doubt they are the problem.

Sorry guys, it's not the gas cap. They remove the gas cap during the test. That is where they apply the pressure. :tear:

return line leaking?

scottmcneal said:

return line leaking?

Click to expand...

Not sure. Nothing actually leaks liquid, only vapor, so hard to tell.

check all your clamps, then check rubber lines for cracks

On my 90 I had the same compression situation. I pulled the head and took it to a local (very good) machine shop. I walked in and told him I had a Jeep 4.0 head in my van. He said, "is no. 1 low"? He walked out, put the head on a cart, threw on the magnet and sprinkled the powder between no. 1 and no. 2, showing a crack in the casting. He said it's a very common place for these to crack. He rebuilt it on a fresh casting (all the valves and springs were good).

So I had to somewhat drop the tank. I replaced the two grommets at the two vent valve locations. Pretty easy job really. Then I took it back to emissions. Guess what, failed again. I knew the shop wasn't right. That is why I never bring my rig to shops. I hope they will be willing to look again since that's what I paid them for and they were not correct. The grommets I removed were in great shape. I kept them as proof. The odessey continues...Where is this pressure leak coming from? Also, can I ask the shop to warranty their work and look again?