Kjc50

My Jeep is having issues to put it nicely first is the crack in the exhaust manifold, I believe that what started this whole run of events again being nice, started off running rough and rich I'm thinking it's because of crack above o2 sensor and has become a real pain in the ***, I've changed, map, tps, o2, vacuum line, fuel filter, the last change was yesterday for the map TPS and O2 and it seems the alternator has gone out also when I tried map sensor with key off the hot wire gives me 4.8 to 5 volts and ground ohms turn the key and ground go straight to 5volts ( I would guess that means short some where? And if that's not enough I'm now having to deal with heat soaked I believe is what they call, I just now that it gets heat enough to boil the fueling the rail and if I release the little valve o the rail it's Uber a lot of pressure and let's out agood pint of gas before it died all together it was costing me 50 to 65 a day in gas. I really love my Jeep but money's tight especially when I don't know what's wrong or even where start. Any and all help is greatly appreciated

4.3L XJ

You didn't say what year Jeep or engine size. But if you are getting heat soak, you can wrap the fuel rail and get rid of some of that, venting the hood helps too. But fix that manifold. Yes a cracked manifold will suck air into it and make the O2 sensors see a lean mixture and the ECM will compensate with a longer pulse on the injectors

doublechaz

+1 to you won't get anywhere swapping parts while that manifold is cracked.

PatHenry

Yeah, the 95 isn't known for that heat sink stuff - I've never had an issue with that on my own 95.

If you're getting it, it's 99.999999% certain that it's your exhaust manifold leak spewing heat into the engine compartment.

Get a high quality manifold and put it on there. They make all kinds... I put in a Dorman one myself and it seems ok.. but it's hard to tell.

One word of advice - if your front pipe (the one connected to the manifold) is original and OK don't even think about replacing it. The Walker brand I used had the O2 bung completely wrong, the sensor ran right up to the oil pan. I got the other brand that RockAuto carries my 2nd time around... Bosal's el-cheapo I think it is, and the bung was better...

I couldn't find anything of any higher quality for a front pipe replacement - and given the fact I've replaced the damn pipe twice in the course of 3.5 years, if I had it to do over I'd have kept my original pipe and had a new hanger welded on. I made the mistake of cutting the front pipe off before realizing I SHOULD have cut the 2 bolts between the manifold and front pipe (they're easy enough to get at if you have the intake stuff off and the front driveshaft removed) which would have separated my old cracked manifold from the OEM front pipe.

Kjc50

Ok it's a 4.0 and exhaust manifold pipes were just about in half



Now put another manifold on no cracks, it still ran like crap, new tps,new map sensor new O2 , now I can't even get her running she'll idle but race back & forth high then to almost a stall. Starting think fuel pump put a gauge on at fuel rail and either my gauge is junk or it's pushing way more fuel then it needs because it pegged my gauge. I've been down a week now and lost as all get out what to do now needless to the guy I work for is coming a part at the seams so I need help please any and all thing you guy have is greatly appreciated,
Thank you everyone

4.3L XJ

Sounds like your return line is plugged or the pressure regulator valve is stuck

robertj

Are you running Mopar sensors? I would never have replaced all of that at the same time. If you didn't use OEM, who knows what piece of that puzzle could be causing your issues. For the O2 sensor use NGK/NTK sensors only. Also, you might want to do a bit of a search before throwing more parts at your XJ. Non-OEM sensors are well known to cause issues with the 2.5 and 4.0 Jeep motors.

bluejeep2001

Too bad your all back together..the lower coolant hose looked like it was worn almost through. Unplug your o2 sensor...if it gets better then thats your problem. Getting the manifolds on correctly and flush with the block is difficult at best. You might not be seated correctly

Kjc50

Thank you I am out at the jeep going over everything y'all said no if but when I get her running I'll sure let everyone know sure appreciate all the help and friendly advice because I'd be lost without it.

Kjc50

I'm not to sure how this return @the regulator works but it seems to me that if I pull the line off some fuel should be coming out when trying to start it yes , no , maybe?
Also when I tap the gas it dies rt off. I can pedal it and keep it running for maybe a minute before it dies.

4.3L XJ

When the engine is off, it only runs for 2 seconds when you turn the key on, then runs constantly when the engine starts

Kjc50

No I'm sorry I should proof read what I typing my typing skills suck,. When I get it started if I tap the gas pedal it will die right away and if I don't tap it will run maybe a minute and the idle racing high then low to an almost stalls a few times before it finally does stall.

4.3L XJ

If it was me, I would verify fuel pressure while running. That will tell you more than what you are doing

Kjc50

I put the gauge on my gauge pegged out so not what's going on, is possible that the pressure is really that high and if so what might cause it. I'm checking return line to make sure no clogs.
Thank you again for everyone's input it is greatly appreciated.

bluejeep2001

The little rubber line is a vacuum line...there should be no fuel on the line or the fitting...with high vacuum/ idle ish it keeps the regulator at low pressure mode. When you remove it or stomp on gas the vacuum drops and the fuel pressure increases to help with high rpm fuel demands