COMPUTER FOR 1994 JEEP ZJ

JSJJ388

JSJJ388

GREEN GREMLIN
Joined
Aug 31, 2016
Location
HAMPTONVILLE, NORTH CAROLINA
My ZJ has been sitting for a few years now because it wont run. It cranks and then spits and sputters and makes a loud sucking sound from the intake. Ive tried every sensor, checked fuel pressure, injectors, dizzy, plugs, wires, the whole gamete. Thinking it might be the computer. In full disclosure, these problems started when I swapped in a junkyard 4.0, but the engine was seen running. Reason for the swap was a broken piston skirt and a chunk of block missing. Does anyone have a computer I could try to see if thats it? or any suggestions on what to try? Info here : https://nc4x4.com/forum/threads/92-4-0-surging-and-hard-start.181494/
 
JSJJ388 said:
My ZJ has been sitting for a few years now because it wont run. It cranks and then spits and sputters and makes a loud sucking sound from the intake. Ive tried every sensor, checked fuel pressure, injectors, dizzy, plugs, wires, the whole gamete. Thinking it might be the computer. In full disclosure, these problems started when I swapped in a junkyard 4.0, but the engine was seen running. Reason for the swap was a broken piston skirt and a chunk of block missing. Does anyone have a computer I could try to see if thats it? or any suggestions on what to try? Info here : https://nc4x4.com/forum/threads/92-4-0-surging-and-hard-start.181494/
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I might have one from a 99 or 2000 with a 4.0. It's probably far enough away to not work though.
 
justjeepin86 said:
I might have one from a 99 or 2000 with a 4.0. It's probably far enough away to not work though.
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probably so. zj was 92-98. thanks though,
 
Jody Treadway said:
93-95 are first gen, only they interchange.
I'll bet you $5 and a dirty sock that your dizzy is installed wrong.
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Care to elaborate? I reckon it's certainly possible it's on wrong.
 
JSJJ388 said:
Care to elaborate? I reckon it's certainly possible it's on wrong.
Click to expand...
Sure thing
First, let's verify if the dizzy is correct or not.
Remove #1 plug, turn engine via balancer bolt (3/4") by hand until compression is felt through #1 hole. Align the notch on the balancer with the "0" mark on the timing cover. You're at #1 TDC compression stroke now.
Remove dizzy cap, rotor and cam sensor. There's a hole in the dizzy body and a corresponding hole in the metal cam sensor reluctor wheel. Do the 2 hole line up so a 3/16 screwdriver, drill bit, etc will pass through? If so, it's timed correctly. If not, proceed to next step.
With timing untouched, pull dizzy, use a flat screwdriver to turn oil pump drive to approx 10 o'clock. Put that 3/16" diameter bit back in the dizzy and drop it in. If it doesn't fully seat, turn the oil pump drive to 11 o'clock and reinstall.
Holler back as needed. Your symptoms are those of a incorrectly installed distributor.
PCMs in early ZJs rarely, if ever fail.
 
Jody Treadway said:
Sure thing
First, let's verify if the dizzy is correct or not.
Remove #1 plug, turn engine via balancer bolt (3/4") by hand until compression is felt through #1 hole. Align the notch on the balancer with the "0" mark on the timing cover. You're at #1 TDC compression stroke now.
Remove dizzy cap, rotor and cam sensor. There's a hole in the dizzy body and a corresponding hole in the metal cam sensor reluctor wheel. Do the 2 hole line up so a 3/16 screwdriver, drill bit, etc will pass through? If so, it's timed correctly. If not, proceed to next step.
With timing untouched, pull dizzy, use a flat screwdriver to turn oil pump drive to approx 10 o'clock. Put that 3/16" diameter bit back in the dizzy and drop it in. If it doesn't fully seat, turn the oil pump drive to 11 o'clock and reinstall.
Holler back as needed. Your symptoms are those of a incorrectly installed distributor.
PCMs in early ZJs rarely, if ever fail.
Click to expand...
Had no idea about this, so its certainly a possibility. I'll see if I can get time this weekend to check that out. Thanks.
 
So, my dizzy doesn't look like it's right.

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