So my 98 xj 4.0 has a couple problems that I think I've linked to fuel pump issues. Rough idle, hesitation, occasionally stalling, also another issue when the engine won't accelerate right after takeoff. Newer plugs wired, cap and rotor, cleaned throttle body, opinions welcomed

 

Check the pressure with a gauge and you will know if you have a problem.

 

fuel filter swap

then focus on CPS

 

'98 ain't gotta fuel filter

 

sorry .. only owned square body xjs

his symptoms are almost identical to mine .. CPS culprit

and .. changing all throttle body sensors to Echlin / Napa ... runs way better shifting

 

[QUOTE=
his symptoms are almost identical to mine .. CPS culprit

and .. changing all throttle body sensors to Echlin / Napa ... runs way better shifting[/QUOTE]
So what were your exact symptoms???

 

No Codes shown .. stalls with no warning or reason .. fires right back up in neutral (while rolling even) or park .. then fine for 50-100 miles .. then stall out of blue

slight misfire now & then .. Rough idle, hesitation, occasionally stalling, also another issue when the engine won't accelerate right after takeoff or stalling on takeoff or rounding a corner

bucking on highway when it should be switching gears / idle adjusting correctly to said shifting also .. ghost stalls .. rough starts (sounds like a tractor, then picks up to idle)



I lost the link for testing CPS connector with engine off. will look for it

unplug it .. run multimeter across 3 pins a-b, a-c, b-c .. apparantly b-c should be infinite / open signal / no resistance


I got weird readings on all .. quick resistance then infinite .. or resistance .. or infinite .. or stable # .. then I would switch my red/black probes - complete other readings


I just called it toast, driving great now, shifting esp..


other tests include voltage .. I didnt do that, I felt ok replacing it .. after seeing it go berzerk with no power / multimeter

and spent the week prior: tested fuel pressure OK, I tested it for 1/2 hour ... shop ran it for an hour or more on scope / pressure tester .. nothing found .. would only stall while driving

 

I wouldn't believe it if it didn't work for me. Sane issues. Changed CPS, rotar cap plugs and wires. Fuel filters and still had the problem. My grandpa told me to check to ect. It was a little corroded but figured if buy another one. Fixed all my problems from starting and idleing driving. Sounds silly but 11 bucks was worth it to me