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96 Cherokee will not start

M

MikeRez

NAXJA Forum User
Location
MT
I have a 1996 Cherokee 4.0l Auto... Will not start. I have replaced the plug wires, cap, rotor. I am getting spark and fuel pressure (50ish PSI) and what looks to be fuel puddled in the bottom of the intakealong with a gassy smell. I have read so much stuff on this forum for "no starts" but i can't find anything that sounds like my problem.

I recently purchased the jeep for $600 the ad read something like "runs rough but runs".

So i have spark, fuel pressure and the engine turns over. When i open up the TB I can see fuel puddled in the bottom and after cranking for a few seconds there is a strong gas odor.

LOST! please help!
 
So, you got it, it ran, you drove it home. It ran until you changed the parts, or it quit running and you changed the parts? Or you changed the parts, it ran good for a while, and now it won't start?

When you pull the spark plugs, what do they look like? Oiley, tan, white, wet with gas?
 
it wasn't runing when i got it. the plugs look new just gas soaked ( i pulled them all and dried them). The ad sad "runs but runs rough". When i contacted him he had replaced the fuel filter and told me it wouldn't run at all now. He also stated that it was heating up and thought the head gasket might need replaced. I haven't seen any signs of head gasket problems i.e no water in oil. Oh yeah, he did replace the thermostat and thermostat housing and it looks to be a new temp sensor (he gooped the orange RTV on so thick).

i would appreciate any directions i can get at the moment,

Thanks,

Rez
 
I'm not sure, but for a Renix fuel PSI would be 30 and 39 with vacuum disconnected at the regulator.

Is 50 PSI too much for a 96?
 
I belive 50PSI is good...i think i read 49 +/- 5 is good. It won't start if i hold the pedal down...it just wont start. What concerns me is the amount of fuel sitting in the intake just below the TB. All i should need is spark, fuel and air. I have 2 of the 3 im just not sure on the air.
 
I know 49 is the fuel pressure spec for my 99 but I'm not sure that it is for a 96. I'd sure verify that; maybe somebody has a definitive on this.

If the spec is 31, then 50 is no good....you may have a regulator problem, which I'm pretty sure is part of the fuel pump assembly on a 1996 model. But even if it is too high, you'd think it would still fire up but run poorly with excessive pressure??

But it appears the previous owner was addressing fuel delivery issues (said he replaced fuel filter, then didn't run)and so with you having spark, I'd start by ensuring that fuel delivery is within spec. If you have a strong blue spark, your problem is probably not crank sensor related.

Even with it not running, you could hook up a code reader or a scan tool and check for fault codes which may be helpful here if you don't stumble onto the root cause of this. I would highly recommend that.
 
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I say it is very flooded out as a possibility. Open the TB and hold it open for awhile, let the gas evaporate out for a little bit. When you go to start it next, if it still won't fire after a couple cranks, put the pedal to the floor. Should fire up then if you have spark.
 
I found a TSB (14-06-97) on another site stating that the 1994 - 1996 (XJ) Cherokee fuel pressure specification - 49 psi - plus or minus 5 psi.

I had the TB butterfly proped open all night.

If I'm getting spark then the CPS should be good, right?

I don't have access to a code reader. Can i jumper some pins to get codes?
 
Sounds like spark is good. Is it at the right time? You replaced the cap and wires, but is #1 in the right spot and is the order correct after that? Mine doesn't have the distributor, but IIRC, the cap has a number 1 on it where the #1 wire goes. And there should be a mark on the housing were the rotor should point at #1 TDC compression.

Even if you replaced it all exactly like it was, it wasn't running when you did that, so you don't know what shit the PO left you with.

Yea, CPS "should" be good if you have spark.
 
i verified the firing order with the Haynes manual. I have tested all the sensors they are good. With the "tit" up on the CPS sensor which pin would be pin '"a". Would it be possible to have a half functioning CPS? I was checking it AGAIN and the readings seem to have changed to around the 500 ohm range. i just wanna be sure that i have the right pins before i replace it. Last time i checked it it showed open on 1 of the pins now its showing 500 on both....hmmm. Maybe i better go check my meter settings :)
 
Well...i just completed compression tests. 1 & 2 at 30, 3 & 4 at right around 0, 5 & 6 at 130 ish. Looks like i hafta pull the head and replace the head gasket. I'll be back :)
 
Something else to consider in this circumstance is that all that fuel can wash down the cylinder walls and drop your compression. Maybe not that much but the problem can be significant enough to prevent it from starting.

I was given an 87 with similiar issues once upon a time. A spurt of trans fluid in all the cylinders and low and behold it started. And continued to start every time after that for the remaining years I had her. YMMV
 
What he said. Is there any way you can pull a fuel rail out and still have the injectors connected and the top o-rings will keep the injectors in place even with ~50psi? If so, then you could see if one or more are leaking(they'd do that with ignition on when the pump primes), which would give you a low compression test due to the cylinder wash. There's just too much gas in the intake to not suspect a leaky injector(maybe if you tried to start it 50xs in a row. . .).
 
have you tried the self diagnosis codes? that could tell you if any sensors are faulty i just did mine and came up with a bad cps and vss
 
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