Hesitation when accelerating

Hi everyone, I been having problems with my 1994 xj40 4.0 when I accelerate from a dead stop and also when I step hard on the gas while driving at speed. This has been an intermittent problem for over a month and it is more frequent. Three times this week it hasactualled stalled and I had to restart. I now have to be cautious when pullng out into traffic and allow enought distance to allow time to restart if needed. The car runs great between these episodes.

Gary, when was the last time you changed the fuel filter? You can also check the fuel pressure. Are you getting any code(s)? Check the plugs too. Is the idling stable?

It’s in the shop now for something else. This morning when I pulled out of my driveway it stalled dead blocking both lanes with a crest of a hill 100’± to my right. I took 4-5 seconds to restart. Luckily there was no traffic. I had the mechanic replace the fuel this morning. He will diagnosing it today. There is a tuneup replacing plugs, wires, cap, rotor less than a year ago. Several month before this ploblem started I cleaned the oxygen sensor and mass air flow valve using the proper cleaners for each.

When the donut seal failed in the fuel pump canister, the acceleration was very slow and I heard a popping sound from the engine bay when I gave a bit more gas.

I have not checked for codes or fuell pressure. The mechanic will do that tomorrow. My mechanic is good but he is not a Jaguar specialist. I live in a small town about 80 miles from a trained foreign car specialist. I am lucky he is even willing to talk to me about it.

I have not noticed any poping sound but I will pass that info on.

I did mention the charcoal canister. Cracking the gas cap to vent will be the last resort if all else fails.
Thanks for all your input.

Check the wiring from the crank shaft position sensor for any break in the insulation that might be allowing a leak of the CPS signal to the ECU.

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try cleaning the MAF sensor plug and connectors

Should have looked into it sooner, sounds like a fuel delivery problem, and most likely just the filter. The pop would’ve been a misfire from giving it more air but not enough gas to go with it

Hi Robin, I have a new css in my stash of spare parts. I will get it installed roday. Thanks

Gary …

Stalling or hesitation is generally caused by …

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Initially I had my xj40 in the shop yesterday to have my front rotors turned and then it turned into a diagnose of my a acceleration issue. He replaced the fuel filter but without Jaguar specific experiance all he could do was to look at all the regular suspects for obvious fuel/vacuum leaks, disconnected/loose wires, etc.
I picked the car up today, drove about a mile to the first stop light where sputtered and died. I get her restarted, took her to a back road and put the pedal to the metal and let her rip. After numerous stops and hard acceleration without futher issues l got back into normal traffic and drove around awhile. So far, I have not experianced anymore bad behavior. I am hoping, since I have only been using her for a grocery
getter, all that hard acceleration blew the cobwebs out of her. I am hopeful but still cautious.
Thanks to all who were kind enough to offer your suggestions. Wish me luck.

So you did an Italian tuneup.

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