1996 intermittent loss of engine power

I have checked the post’s and can’t quit find this problem. 1995-6 XJ IL6 4.0L 145k+ 4x2 automatic transmission, basically all stock and getting older so I know I need to do a lot of work to keep it running good.

Well that brings me to my problem, after the engine has been running for roughly 10 min or 5 hard, the problem happens while I accelerate (sometimes), and the engine will hesitate so I release the gas pedal and reapply slowly to achieve my speed. The next time I come to a stop or slow down and have to accelerate again the problem worsens and I have to lightly pump the gas pedal to attain a comfortable speed in traffic, at this point the hesitation becomes so bad its like my jeep is coasting, and keeps getting worse and worse to a point at witch I am pumping the gas almost to the floor and the engine is revving up but sounds like it is bogged down and a couple of times even made a clunking sound, then it will get to a point where I am flooding the engine and I need to let off the gas for a couple of seconds so it will not to stall out, witch it has stalled a few times how ever when I start it back up, it has no hesitation and drives fine for a min or 2 then the problem reoccurs and progressively worsen much faster.:confused1

Checked the gas tank and found debris cleaned it out and made sure the pump was working properly checked all the hose changed the fuel filter, changed the air filter cleaned the throttle body, flushed the injector rail, cleaned the injectors, sea foamed the tank and used 93oct, changed the distributor cap, rotor, sparkplug’s and wires, and have replaced the oxygen sensor. I am starting to run out of spare change so I’d like some help narrowing it down a bit, so I can leisurely get every thing else back up to date.

Since you say when you restart it it drives fine again leads me to believe it may still be the fuel pump even if you tested it. Mine tested fine but once replaced solved a problem similair to yours. With my problem pushing the pedal harder only made it worse, but it may be something to look into.

Hallo. Is the behaviour of the engine related to temperature?
Some components are culprits when getting hot.


'92 XJ

wim hoppenbrouwers said:

Hallo. Is the behaviour of the engine related to temperature?
Some components are culprits when getting hot.


'92 XJ

Click to expand...

Yea, it could be temperature related; coil pack, CPS, distributer fuel pump,.. my guess would be fuel. The pump may be going bad or the strainer on the pump may be blocked/partially blocked.

My XJ once did that. I left it sitting for 10 months with less that 1/4 of gas. Got back to the US filled the tank and kept on driving. About 3 tank fulls later she started doing the same thing you described. I had to take the tank out cleanned a lot of gum that looked like shelac out of the tank, cleaned the strainer on the pump and replaced the in-line fuel filter a couple of times.

Take a look at the in-line filter, better yet, replace it. It is easy and inexpensive. An inspection of the filter would give you an idea of the rest of the fuel system.

I'd advise getting a manual and a multimeter. Check your throttle position sensor. Also get a fuel pressure gauge, you can rent them at places like Checker auto and advance auto. A fuel pump could still be the culprit.

I'm with Jeepm@n.

1. Test fuel pressure with a fuel pressure gauge. Only true way to determine fuel pump functioinality.
2. Test throttle position sensor

Test your way to a solution; I agree with you that throwing parts at this on a hunch is expensive and never is particularly effective. Let us know what you find.....

Ok yesterday my check engine light came on and it’s giving me 3 codes P0132 bad o2 sensor (the one I replaced), P0171 fuel mixture to lean, and P0172 fuel mixture to rich. So this morning I tested both o2 sensors and they are operating fine, and I tried to recheck the fuel pressure while it was acting up. This time there was a blurb in the fuel pressure as I attached the gauge (vapor lock?). I could not seem to get the engine to hesitate the way it was while driving, playing with the throttle but this time the gauge was dropping from 50psi to 20psi as I revved the engine, before the psi was at a steady 50psi (when I tested it when I cleaned out the tank). I am pretty confused if it’s going bad or not and maybe a really bad vapor lock I the lines. How could I purge this? And how ca I test the CPS?

Thank you all for you input
Randy

A drop to 20 psi is your problem. The pump, a plugged line, a plugged filter, and a fuel pressure regulator all could cause it. The ECM cannot adjust air fuel ratio or injector pulses with that much of a drop in fuel pressure. Thus giving you a lean and rich code.

Crank position sensor (CKP) usually stops motor all together. Fuel pressure issue could also still be electical. You could check the ground.

Cyanide_Trip said:

Ok yesterday my check engine light came on and it’s giving me 3 codes P0132 bad o2 sensor (the one I replaced), P0171 fuel mixture to lean, and P0172 fuel mixture to rich. So this morning I tested both o2 sensors and they are operating fine, and I tried to recheck the fuel pressure while it was acting up. This time there was a blurb in the fuel pressure as I attached the gauge (vapor lock?). I could not seem to get the engine to hesitate the way it was while driving, playing with the throttle but this time the gauge was dropping from 50psi to 20psi as I revved the engine, before the psi was at a steady 50psi (when I tested it when I cleaned out the tank). I am pretty confused if it’s going bad or not and maybe a really bad vapor lock I the lines. How could I purge this? And how ca I test the CPS?

Thank you all for you input
Randy

Click to expand...

Have you been able to find the problem?