My 97 jeep cherokee quit working on my recently, and I (perhaps improperly) diagnosed it as the fuel pump. I replaced the fuel pump, and the jeep kicks, sputers, and trys to start, but it won't sustain. I have replaced the fuel pump, filter, and CPS. Now, the latest wrinkle, I have exhaust comming out my air intake.

Any help would be greatly appreciated.

 

it is either out of time,or you have a valve either intake or exhaust stuck open,that is the only way exhaust can come out of your intake. it is possible your timing chain has slipped.

 

So, I checked my handy-dandy chilton guide and it turns out my jeeps timing is controlled by the PCM. Nothing I can do there (from what I understand). Is it possible the cam-shaft position sensor could cause the problem?

 

you are right about the pcm,and yes the cam sensor can cause problems like this,but it would have to be firing out of time,most of the time they just quit,but it worth a try.

 

prob a valve issue, i personaly haven't seen a timing chain skip on a 4.0, has anyone ??

 

So, if I understand my odds, cam shaft position sensor is possible, but unlikely, with a stuck valve being the most likely.

Is there any other diagnostics you guys could recommend?


EDIT: Oh, and for what it helps, this thread is a continuation of the problem I spoke about on this thread: https://www.cherokeeforum.com/f2/cherokee-sputters-kicks-but-wont-start-19223/

I had (apparently) misdiagnosed the problem as a fuel pump. Either that or the fuel pump was a sympathetic failure.

 

this recently happened to someone else on here and what they found was one of the push rods had actually fell off the lifter,it may worth a shot,remove your valve cover and make sure they are all in place and tight.

 

A simplier thing which could cause exhaust in the intake would be the bolts backing off of the intake/exhaust manifolds. The exhaust could easily enter the intake ports on the manifold. It may also answer the fuel suply problem which you also mentioned.

 

Ok, if I understand things correctly, the next easiest thing to do is to remove the Valve cover and take a look at the valves. Will it be obvious if one (or more) of the valves is stuck?

Also, I looked on autozone's website, and I see a valve cover gasket (which runs about $50), but the chilton guide says nothing of a gasket, just som RTV sealant. Is the gasket nescessary?

 

Valve cover gaskets are not that espensive,you should be able to buy a cork gasket for a lot less,or even a rubber one.. If you had a stuck valve that will not reseat it will be apparent,but you would have to rotate motor and look for loose push rods. The situation I mentioned earlier the individual found the pushrod laying in the hole but not connected,that would be very visible.

 

I don't remember if the 97 has an EGR, if the valve is stuck open you will have exhaust in the intake and it won't start.

 

The egr was removed in 91 when they came out with h.o motor.

 

Well, I opened up my valve cover, and nothing looked horrendously broken, but from what I understand, I need to see them in motion to be sure.

I was thinking of removing the power to the spark plug, so there is no ignition, and then having a friend try and start the car so I can see the valves (well, pushrods and rocker-arms, anyways) in motion. Is there any problem with this plan?

Also, what should I be looking for? Listening for? Smelling for? (hey, you never know...)

 

Well let me ask you a question: yow do you know you have exhaust gases in your intake? are you sure it wasn't just a backfireing and build just a little smoke?

 

Well, after trying to start and getting it popping and firing for a short time (chugging along a I feathered the throttle, but never idling), the filter box would be full of a grey smoke that smelled like exhaust. Admittedly, I don't know if it is, indeed, exhaust, that is just the first thing I thought of.