Dolphin

I'm helping a friend with her 89 Cherokee which is stuck in her driveway with the crank no start issue. It has the 4.0 inline six. She says it's a parts engine from a 93. I've read almost every "crank no start" thread on the forum and I haven't found the issue.

Originally, I was just checking for spark and found a cracked plug. So I replaced the plugs, wires, rotor cap and button. Still nothing. Next, tested the cps sensor. It passed the ohm test but read 0 volts. Replaced it with AutoZone cps. Same results from test, but now new symptom while cranking (see video). Since this one tested with 0 volts I tested my multimeter to make sure it's reading correctly and managed to get a refund from AutoZone. Purchased a cps from NAPA. Same issue and same test results. Passes ohms but 0 volts.

So now I'm at a loss. I want to test the ICM but only have a multimeter and can't find a test. I've tried swapping and tapping relays. All in cab fuses are good. Based on the new crank symptom in the video I'm worried it's timing related. I tested the fuel injectors and they are good.

Video: https://docs.google.com/file/d/0B4rH...p=docslist_api

Instead of just infinitely cranking it is now kind of bogging down. If the cps is unplugged, it doesn't happen. Plugged in, it's bogging out.

I can't check ecu codes because her check engine light doesn't work.

Any ideas?

ehall

got another battery laying around?

Dolphin

We tried it with and without jumper cables, no change. I had the same thought :P

ehall

I would skip the battery in there and try another one straight

perez1989

Crank position sensor, fuel pump, module. Those cause crank and no start. Check those first.

DFlintstone

don't go away just yet. You have unpluged, repluged the cps. Yo hear the fuel pump run a second when you turn the ign on.

DFlintstone

OK, saw the vid. #1 is at the 5:00 position as viewed from the passenger side. 143624 clockwise. (the book is wrong).

The MAP sensor up there left of center on the firewall should have a tube going to the rubber plug on the inside of the tb. OR any intake manifold vacuum. VERY important that, the vacuum to the map. (and the firing order)

Dolphin

I'll have to check the fuel pump somehow. I don't have a fuel pressure gauge. I have unplugged and replugged the cps more times than I care to count. I've been assuming the fuel pump is good. Again, I used the multimeter to verify the injectors and I know there is fuel at the hose connecting to the fuel rail. Should I try to crank while that is detached and see if fuel sprays out?

Dolphin

Edit: link didn't work, but that is the firing pattern I used.

DFlintstone

My main point (poorly written), is that #1 is at 5:00 as viewed from the passenger side. The sound of yours cranking ....just double check please! And in your Vid I see no Map tube. That sucker is mucho crucial. Lastly, can you see the info in my signature? (or are you on a "smart thing"

DFlintstone

Here, where the yellow thing is, is #1, then 143624 clockwise from there.

Dolphin

I will definitely check the map tube and the sensor itself. I don't want to get to far down the rabbit hole so I keep coming back to this question. Why is there no spark? I followed the cps write up in your signature btw. This forum has already been immensely helpful, we just still don't have a running jeep.

DFlintstone

*

DFlintstone

OK, I ran in head-long and didn't read well enough to get you have no spark. Here is a caned CPS deal >.

#1 Unplug the connector at the back of the manifold with wires going down to the bell-housing/cps. (it's a three wire plug, with only two wires)
#2 Probe the two wires to the cps with the digital meter set on AC volts, a 200 scale on mine. Yours meter may have a lower 2 Volt, or “auto range”.
#3 Crank the engine and note the voltage. (jump it if your battery is low). .35 ( is minimum. .4 to .8 is more like it.

So there is that. Without a signal, the ECU will not tell the ICM or the injectors to do anything.

Has she ever had it running? The torque plate from a 93 does not have the correct notches that an 87-90 uses. (the CPS senses spaces in the torque plate, they changed between 90 and 91)....That might explain the odd cranking, it tries a little sometimes. JUST A THOUGHT! Could well be something simple.

ehall

I swear it looks like the battery is running on 9V. Undervolting does a lot of weird stuff