Fuel Rail

Hey guys, does anyone have a fuel rail laying around for a '98 4.0 Somehow I am getting air into my fuel lines, I have had a smoke test done on the fuel lines from fuel rail back and nothing was found so I want to throw in a new fuel rail and see if it may have been leaking from there somehow. Somewhere between the fuel pump and fuel rail test port I am loosing about 25psi and like I said we have tested the fuel lines and bench tested the fuel pump so what else could it be. any suggestions. Thanks everyone

Try replacing all of your injector o-rings. They are fairly cheap. Fuel can leak out of there and evaporate before you can see it so it's hard to tell that they are leaking there. It makes sense that as the fuel in the rail cools it can draw air in through a bad 0-ring.

awesome, thanks John. Also, on kragens website they show a part for o-rings for the ends of the fuel rail itself, I will try thoes as well and see whats going on

Good luck dude!

What is the pressure reading at the rail? I've never seen o-rings on the newer ones go bad. If they were leaking 25 PSI worth of fuel, it would be noticeable. Can you smell fuel? like the line might be cracked? any noticeble leaks?

It kinda sounds like a fuel pump issue to me. I know you said you bench tested it, but it could still have an issue pumping fuel 10ft to the front. It could also be a volume issue, where it has the pressure, just not able to supply the amount of fuel


Justin

i think '98 should have a pulse damper thing on the rail. if it does, try replacing the rail with an earlier HO model that doesn't have it. never seen one go bad on a jeep, but did see one go on a toyota once, caused some pretty odd running pressure issues.

pressure at the rail was 26psi, i replaced the fuel pump, regulator, filter huge ass canister unit and it changed nothing, I have replaced pretty much everything on that vehicle before finding out that there was air getting in lines somehow. Not sure whats going on. I have literally been chasing this for 9 months

OK guys. I officially need help. I tried to fix it on my own but cant seem to get it to work. My 98 Xj is running like crap and getting worse and worse every day. It is now to the point where I cant even drive it. It idles like crap, any time I put load on it it dies out and starts backfiring like crazy out of the intake. Here is a list of items I have already tried.

Spark plugs
wires
cap
rotor
fuel filter
fuel sending unit
fuel pump
throttle position sensor
idle control motor
MAP sensor
crank position sensor
both 02 sensors
cat converter
ECM computer
I had a vacuum test done
I did a compression test. All cylinders are between 147 and 152

I'm stumped :dunno: