1997 4.0 bucking problems???

[cobrah]

Ok I have a 1997 cherokee with a 4.0 auto. I have developed a problem and am unsure on where to turn. Sometimes the things runs great but now more often than not I have this problem. The problem is I can be driving down the road and the car will start to buck and spudder like it is not getting fuel, when the problem first started I could throw the transmission into neutral and pedal the gas and keep it running now I cannot even do that. It also does this sometimes coming to a stop and a light. It will sort of backfire sometimes when this happens. I have not put a gauge on it to see what the pressure is. I have a few things I suspect may be the problem. Either the pump, filter or pump module itself may be bad or it may be the CPS. My questions are could the cps cause these symptoms? The car doesnt do it all of the time just sometimes. Please help me.

[discnik]

The CPS could cause these symptoms, but if I remember correctly they are a pain to replace, I would test the fuel pressure first: 47 - 51 psi @ idle. Also test will driving, tape the gage to windshield without obstructing your view, and see what the reading is.

I would do a resistance test on the coil also: Primary windings= 1.11 - 1.25 ohms, Secondary windings = 7.7 - 9.3 ohms.

Also before condemming the fuel pump test the Fuel Pump Relay.

Hope this helps.

[cobrah]

Also when it starts the missing at idle the engine starts sucking so much air you could hear it from 100 yards way like its trying to suck air through a straw. Only code I got from the three click method was 42

[cobrah]

I see this code is the asd relay. I searched the web a little for info and found one post where someone said if the crank sensor voltage was incorrect it would set this code. I am leaning more and more towards this sensor.

[fredjacksonsan]

Sounds like you're right. There's a how-to in the "How To" section

[ufdan25]

I had a similar problem with my 2000 Cherokee. It would shut off unless you kept your foot on the gas pedal.

Its happened twice to me. The first time I had the sensor replaced but that did not solve it. I then replaced the battery and the problem was solved...

The second time, I noticed it only happened when the outdoor temp was below ~55 degrees. Summer is here and the problem has gone away and hasn't resurfaced with no repairs made. I suspect I'll have some work to do come december. good luck