Spits and Sputters after an hour or so why?

[MaineiacNC]

My 2005 TJ 4.0 6 speed manual spits and sputters after about an hour or so of driving; about 30 minutes on road then about 30 minutes on a gravel road and then the spitting and coughing starts. Like she’s out of fuel, but that’s not it. Guy I bought it from says fuel tank is out of an earlier year which had a different venting system. He says run it with no gas cap and no issue, but after an hour or so issue. Bad. Thoughts on how to best troubleshoot and fix?

 

[macleanflood]

I'd probably start with monitoring fuel pressure.

You don't have a Schrader valve on your fuel rail... Racetronix has an adapter or you can replace the rail with one that does.

I'd tape the gauge somewhere I can watch it while driving.

-Mac

 

[jjvw]

.... He says run it with no gas cap and no issue, but after an hour or so issue. Bad. Thoughts on how to best troubleshoot and fix?

Did any TJs not use a vented gas cap?

 

[danielfrench100]

I had similar symptoms on my TJ—it would run fine for a while, then sputter like crazy. Turned out to be a failing crankshaft position sensor. Heat would cause it to cut out intermittently. Swapped it out and the issue disappeared. Definitely check fuel pressure too, but don’t overlook sensors—they’re sneaky when they start to fail gradually.