ZombiePopper

Hey guys,
Sorry for the long post but
I really Need some assistance with a 94 ZJ limited 5.2 I just picked-up.
It start/ran/drove but ran poorly, it acted like it was missing and it was lightly popping occasionally like a quiet backfire and I had to keep my foot on the accelerator to keep it running, and I'm not seeing any lights on the dash.
Now,
It doesn't even want to start, and still no lights on the dash.
It cranks, catches then crank, catches etc etc but doesn't start and there's a strong smell of gas.
I was told by the orig owner he thought it was a head gasket so here's what I did;
-I pulled the plugs looking for rusty electrodes but they were clean but had gas on them (plug in #2 cyl was broken so I replaced all the spark plugs).
-I then pulled the oil pan drain plug looking for evidence of coolant in the oil but there was only oil no coolant and the coolant in the radiator is clean/green. So I changed the oil and oil filter. (The oil was well above the normal level on the dipstick though).
-I then pulled the valve covers looking for coolant on top of the heads (but there was just pools of oil.)
-I then swapped in a known-good IAC Sensor but no change.
-then I replaced the TPS and MAP sensors but still no change.
-the plug wires looked old/tired so I swapped on a new set of plug wires 1 at a time and while I was at it I cleaned/oiled the air cleaner.

So I'm wondering if my crank position sensor is bad? Could it cause the symptoms above?
Or if there's something else I should be looking at?
I'm stumped here,
ANY help/assistance would be greatly appreciated!
Thanks

Bustedback

Check the fuel pressure before you replace anything else. Screw the gauge to the test port on the fuel rail and then turn the key to the on position. The pressure should go up to around 45-50 psi. Turn the key off and watch the gauge, the pressure should hold and stay pretty close to the 45-50 psi. If the pressure drops immediately you may have a bad fuel pump or leaking injectors. You mentioned that the oil level was pretty high, did it smell like gas too? That would indicate injectors that are leaking and filling the crankcase full of gas. The 318 and 360 V8s also have a plenum plate on the underside of the intake manifold that will blow out the gasket and cause vacuum leaks, oil consumption, and poor running. You can smoke test the intake and see if smoke comes out of the oil fill cap. Just be sure to cap off the PCV hose fitting on the manifold so you don't get a false reading. I will recommend replacing the crank sensor and cam sensor (pickup coil). The crank sensor will be a huge pain in the butt to replace, but they do fail often. I also recommend checking the connections at the PCM. The plug can loosen and cause wacky stuff to happen. Have the battery load tested too. What did you mean by no dash lights?

ZombiePopper

Excellent advice thanks!
I don't have a fuel pressure gauge so I'll have to see about getting one.
Sorry I meant no dash lights as in my check engine light or service engine light isn't on, on the dash.
I have a good/spare 5.9 mag from a 99 ram, should I swap the injectors?
Would a bad crank sensor throw a code and cause a dash light?
(I only ask because I had a 90's OBD1 GM vehicle years ago that a bad crank sensor would not throw a code but the cam sensor would it was weird that they had it set that way.)
I'm in the process now of trying to replace the crank sensor...
What a PITA!
I pulled the overflow tank, pass valve cover, the plug on the ECU, the EGR tube on the pass ex manifold and I still can't get to it!
What's holding me up is the EGR tube nut on the intake, it looks like 7/8's? But can't get enough swing on it to break it free.
Is there an easier way to do this?

Bustedback

No easy way, just a lot of cussing and busted knuckles. A crank sensor won't always throw a code on an OBDI vehicle. I would check the fuel pressure before swapping the injectors.

ZombiePopper

No kidding, my arm looks like it was attacked by a pack of PO'ed ferrets! Lol
Is the EGR tube nut on the intake 7/8's or 22mm?
Also which way should I turn the nut?
(Sounds like a dumb question I know, but can't figure out if it's attached to the tube or intake (I'm assuming on the EGR tube so I'm guessing towards the drivers side))

Bustedback

I'm not sure, it's been a long time since I had to mess with an EGR valve on a 318.

ZombiePopper

No worries I appreciate the input, plus I think its a dumb question because I'm pretty sure the EGR nut is a flared nut and is on the EGR tube plus I'm pretty sure 7/8 is pretty darn close to 22-23mm, but I'll be using a 22mm wrench.

Bustedback

A medium Hispanic socket set (adjustable wrench) will work in some cases.

ZombiePopper

I did it! I changed the crank sensor!
I walked around the yard holding the old sensor at arms length as if it was a monster's heart I had stalked and killed.
Is it wrong of me to wish the engineer who came up with it a painful sexual experience?
Lol
Ok anyway,
So I got it back together and cranked it, cranked it, cranked it, cranked it etc but still no start,
BUT,
Then it happened!
I held the butterflies open on the throttle body and BOOM she fired right up!
AND ran like a top! Much better than when I picked it up, purred like a kitten and revved-up instantly and smoothly and the revs fell back perfectly!
But here's the catch,
I either have to hold my foot on the pedal or keep the butterflies in the throttle body cracked open to keep it running,
As soon as I let go it dies.
So is the IAC respondible for the idle and keeping the butterflies cracked open?
My butterflies look completely closed and all I have to do is just ever -so-slight barely crack the butterflies open for it to start and run.

Bustedback

The IAC doesn't hold the butterflies open, it has a whole other passage way for the air to flow through at idle. It does sound like the IAC is to blame. Change it out, it's about fifty bucks and simple to replace.

ZombiePopper

I pulled the IAC out of my throttle body on my 5.9 and dropped it in my zj and barely thumbed the key and she barked to life! No pedal needed!
But I'm thinking the iac in my 99 5.9 must be bad or just the wrong part # (wrong impedance or ohm perhaps for the 94 zj ECU)?
Because as soon as I put it in gear it starts to rough idle and act like its wants to stall.
So I'm picking up a new IAC today and we will see....
(Just my luck the 1 sensor on the TB I didn't replace-doh!)

Weird question,
You guys with 5.2 ZJ's,
What is your oil pressure at idle???
Mine is showing 70lbs!
Which seems excessive to me.

Bustedback

70psi does seem high, I would suspect a bad sending unit or a wire grounding out. Check it with a manual gauge to be sure.

ZombiePopper

Ok I'm about to pull my hair out (if I didn't shave my head regularly lol)
Need a direction to go here guys;
I replaced the IAC today and she fires up and purrs like a kitten-literally!
Smooth and quiet.
BUT
As soon as I put it in any gear it starts to stumble pop and act like it wants to stall.
I let it run for about an hour and drove it up and down the road and it got a LITTLE better but it still acts like it wants to stall at idle in any gear and pops at the exhaust pipe occasionally and rough idles.
But as soon as I put it in park or neutral it goes back to running great again, smoothly and quiet.
I'd suspect its sucking air but I'd think it'd do it all the time?
Advice? Hints? Ideas?

Info;
Idles about 600ish rpm hot
oil pressure 70psi cold-40psi hot.
Temp holds steady at 210*ish
Alt at about 13ish
Fuel gauge 1/2 tank
No dash lights and it goes in all gears smoothly.

Bustedback

Check the fuel pressure at idle and under a load. I think the spec is 45-50psi.

ZombiePopper

Thanks busted,
I'm doing that first thing in the morning off the schrader valve.