really need some help! engine busting up when hot

[fultorn]

ookay ive done my searching and i have found nothing,. so i am flame free on that issue. but i have a 91 yj with a 4.0.. one ride last year, my jeep got to operating temputure,(give or take around 180) and started busting up and back fireing around 3000 rpms,with no power once so ever.but i got back to camo! got home and hooked the scan tool up, and got a coolant tempture sensor short,.. so relpaced the temp sensor.. everything was fine, until i went to gray rock orv, for spring fling and it started doing it again,.. so i have replaced everything you can think of from alternators to ecus. fuel pressure regulator, MAP, CPS,distuributor, coil. i mean everything. and it only does it when it is hot. i recently hooked the scan tool to it to see if it had any codes,.. and it only has a A/C circut relay code. could this be causing it to cut up when warm. i tried to clear the code but it will not let me,.. this is bothering me.

[Caterpiller]

Sounds to me maybe its mechanical. Make sure your rocker arms are adjusted right. Valves might be staying open once it get up to operating tempeture. Shouldnt do that with a hydralic cam though unless its adjusted wrong.Egr might be sticking open also .

[4130jeeptj]

Mine did the same thing !!! I cked the fuel pressure and i had 23psi so i replaced the entire fuel pump module and its back to 52psi and it does not do it anymore... YJ fuel pressure may differ from my TJ