symptoms of a clogged fuel filter but isnt..

[veeteeesscom]

i have a 5.0 vt ss with just under 100 thou on the clock, and well maintained,but only a few days ago it started acting as if the fuel filter was cloged ..you know the feeling jerking power on power off sort of thing.. so replaced the filter but the symptoms still exsisted, so i did leads, plugs, knuckle skin, and some firetruck words, and its still doing it! ive noticed that when i come to a stop its still at a high rpm as if the choke is on. i stop the engine restart it and it idles fine untill i drive it again, stop and same thing again.. ive also noticed at an idle and nuetralised, the rev counter will flick very quickly at times with no obvious increase in motor speed.. so to define,, jerking under normal driving conditions, slightly high revs at a stand still after driving, could the tps have any thing to do with this, surely it cant be the injectors at only 97 thou, has anyone had these problems or have any other ideas , i cant pull out any more hair its just too bloody cold here at the moment..

[TheIceman]

have any codes??? does it do it at all engine temperatures?? maybe hall effect in dizzy faulty or ignition module faulty.

[don0xer]

my car did some of what you discribe when i first baught it, ended up being the CAS... replaced it and no more dramas

[Tree cutter]

Rev counter jumping is usually caused by an ignition problem. I would look for any wires that might have rubbed through and are shorting around the distributor and coil area or inside the distributor. check around the hall effect switch inside the distributor.It could also be the hall effect switch that is faulty or ignition module.

[wortus]

Have you had a look at the idle air control valve it may be faulty or the throttle body including the IAC passage ways may need a good clean?

You could also check your actual fuel pressure to make sure the pump is working within spec.

[veeteeesscom]

hmm nah haven't done codes yet.. replaced tps today and nudda !!! still doing it so its eliminated and i have been suspect of dizzy problems and or ignition short somewhere regarding rev counter,, plan to go there on weekend and do codes too if i dont get it nutted before hand,thanks for the tip .. TheIcemans question about temp!! its most prominent when the vehicle is at full running temp!!! i had forgotten to mention that cheers...

[veeteeesscom]

yeah thanks wortus i ripped throttle body down today cleaned checked couldnt really tell if the IAC is faulty or not but all seems well, good point with fuel pressure will check that too.. thanks

[wortus]

yeah thanks wortus i ripped throttle body down today cleaned checked couldnt really tell if the IAC is faulty or not but all seems well, good point with fuel pressure will check that too.. thanks

With the IAC out and connected if you turn the ignition on the valve should move up and down a few times. They can get a bit sticky and blocked up but I was told that soaking them in carby cleaner will damage them. I replaced one on my VN when it had a bad idle and it fixed it.
Also have you checked your spark plug lead resistance, there is a maximum resistance and they should all be velow that.