Jeep 4.0 won't start!

SPOA87YJ

SPOA87YJ

Well-Known Member
Joined
Oct 28, 2005
Location
Charlotte
YJ with a 4.6 stroker just installed. Turns over, doesn't have spark and injectors aren't firing. It's running a 92 xj computer and harness. No major issues before the stroker swap.

Computer is getting power
New cps checks good
New distributor
New plugs
Reused plug wires
Grounds:
block to firewall
Block to negative terminal
Block to chassis

Any ideas?? Thanks.
 
Sounds like Hall effect sensor or crank sensor as spark and injector pulse are tied to both.

That Hall effect sensor is in the distributor.

When I first put my stroker together, I had same problem.

Ended up having the distributor one tooth off on the cam.
 
Do this
Here is how to MAKE SURE the distributor is indexed PROPERLY on a 4.0

1-Remove distributor and remove the distributor cap, cam sensor and rotor button
2- Remove #1 spark plug
3-rotate engine by hand until you feel compression coming out of the spark plug hole (3/4" or 19mm wrench on crank pulley)
4-continue to rotate until the timing mark on the harmonic balancer (crankshaft pulley) lines up with the "0" mark on the timing cover
5-Locate the hole on the bottom of the distributor housing. There is also a corresponding hole on the plate that spins inside the distributor housing. Line them up and drop a pin (screwdriver, drill bit, etc) into them. Now the distributor and pickup plate are indexed properly.
6-With a flat head screwdriver, rotate the oil pump (through the hole where the distributor sits) to approx the 11 o'clock position
7- With the pin still inserted in the distributor body, drop the distributor into the engine block. Do not remove the pin if it doesn't drop all the way in the first time. Rather, move the oil pump drive a little
8-When the distributor is fully seated and the retaining hole is lined up, remove the pin and bolt the distributor down to the block.

You are now timed/synced/indexed properly. Period.
 
Scott the distributor is new and the old one was tried also so I doubt its that.

His distributor doesn't look like the ones in videos that describe doing what you posted Jody. We set it again after his posting making it the 4th or 5th time it's been done. Still nothing.
 

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When you turn the key to 'run', prior to turning to start, does the fuel pump cut on and run for a few seconds?

Was the wiring harness donor from an auto?

I wonder if it's getting the signal to start from key, so that spins starter, but ECU isn't getting signal to run so no fuel or spark.

Could be part of Neutral safety switch interlock for auto computer and harness. That wouldn't necessarily disable the starter from spinning the motor, depending on how it's all wired.
 
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When you say the crank sensor tests good, how are you testing it? I usually check them with a digital test light probed on the signal wire, it should flash turning over. Do you have power at the coil and injectors?
 
Here's another test.
Unplug coil connector and jump across the 2 pins (I use a paperclip). Connect a test light from BATTERY power to the paperclip.
Crank engine over. If the test light is pulsing, the crank sensor is functional. If it doesn't pulse, something is no beuno.
It's weird the dizzy doesn't have a hole to align. The sweet spot for #1 is right at 5 oclock if you wanna do a stab and go.

Edit
Make darn sure all the grounds are hooked up and grounded well. Should be one at the dipstick tube stud and more at the coil bra let IIRC
 
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Probably the power steering pump.

I remember having issues with mine on first start and ended up replace the cam position sensor. But that was on the newer coil over plug style.

Have you checked for spark and fuel pressure?
 
just got home, thanks for the replies. It prob is the PS pump :D

I reset the dizzy again to make myself feel better to the 5oclock at TDC so that is good.

I've installed a rail pressure gage and have 45psi but no spark or injectors firing; new plugs are still dry. We tested the injector harness with a lightbulb while cranking and had nothing.

I've tested the CPS while cranking and have voltage so that is working.

The harness came from a manual donor Scott FYI and was running the matching motor since 08 before this stroker was swapped.

The ONLY thing I haven't replaced with new is the coil, damn thing even has a new starter!
 
What was your test for the crank sensor? Where did you measure voltage? With what did you do said measuring? Just because a sensor is new doesn't mean it's good.
 
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