Kris smith

So I just it my second cherokee and it's also a renix. I know most of the common issues and fixes and cruisers write up. But I went to the store today and now it hair cranks and cranks I'm guessing crank sensor. I can smell fuel so I imagine In not getting spark. Question is am I on the right track and is ther any easy way to get the bolts for the sensor ? It's an auto 90 with 4.0 and 231. My last one was easy because I did it when I did my clutch.

DFlintstone

I'd test it first!;

To change your CPS I found if you BACK the fronts onto ramps, you won't have them in the way, where you need to lay. A stand under the left front frame would be in your way.

If CPS itself is putting out less than .35 Volts AC, unplugged, while it's cranking with a good battery, or the resistance is not 200 ohm's plus/minus 75, hot;

11mm socket > 3 inch extension > universal > long (18-24 inches of extension). Your feet are sticking out under the passenger side, you can reach up past the front drive-line with your left hand to hold the CPS from the front. Your right hand is on the ratchet way back by the tranny cross member. If you tie a long string on the old plug, you can use it to haul up the new. Toss that piece of plastic if it's still there, and do not drop the bolts in there! Echlin # CSS980, (from Napa, for 87-90), should be fine, but some prefer to go to Jeep. I wouldn't bother with anything else for that.

If your left forearm is bigger than a quart Mason jar, you might consider removing the front drive-line. Also You might cut your old CPS wires if they go through a deal on a bell housing bolt, then be sure your new are held somewhere safe.

The second one is REALLY easy!




There is a brittle little tube. It comes out of a rubber plug, low on the engine side of the throttle body. It runs back to the firewall, then up to your MAP sensor sort of high up there near center on the firewall. CRUCIAL!! The MAP will tell the ECU to dump fuel with less/no vacuum. Any crack or blockage and it will be pig-rich. (black smoke, fouled black plugs). You can pull the line off the MAP and feel for vacuum with your finger. If it runs!

Kris smith

Already checked the map tube it's ok first thing I checked

Kris smith

Replaced the sensor with a napa one css890 or something like that. Still no start. I checked the voltage while cranking coming from the sensor and I have .3-.1 v at times nothing more. I have had this jeep less than 24 hours and I ca t even drive it. I'm pretty pissed off right now.

Jeepcrazy5722

Did you actually check for spark?

Kris smith

No I haven't. I went right to crank sensor because I had this issue with the last jeep I had. I'm not getting the right voltage from it. I'm ordering a pc307 as per cruisers recommendations. It worked last time. I can smell fuel while cranking. It just will crank and crank. Till the battery dies.

DFlintstone

Well ****. That bites. "I feel your pain". Just to be double clear, you have your meter on the lowest AC scale, (200 on a cheap-o or maybe 2 on a better one), and it's connected to the two wires to the un plugged CPS.

Is it cranking "brisk"? Also Renix needs to crank at at least 300 rpm for a rev or two before it will fire a plug or injector.

Btw if someone put a flywheel from a post 90 HO engine in it it may well not work.

DFlintstone

I just ran out and checked my (Echlin/Napa), since I hadn't in a while. Got a .6

Kris smith

It cranks very brisk till the battery dies. Yes my meter is connected to the two leads and it's a blue point meter auto range I'm getting ............. **** I tested in dc I'll have to re test.

DFlintstone

Well Cool! Yea, gotta be AC.

Kris smith

Well I'll test it

Kris smith

Just checked it. On ac this time. I have .238v ac while cranking. But the battery is getting low. So I assume it's around .3 ac. I ordered a pc307 and should be here in a week or less. I have had great luck with that one. Other issue is I dropped one of the bolts for the sensor taking it out just now into the bell housing. I can't find it I pulled the inspection cover no signs of it it cranks over and it hasn't fallen out yet any ideas short of pulling the tranny

DFlintstone

Boy, you're on a role today! Gads, I don't recall anyone needing to pull the tranny. Fish around with a coat hanger or some tie wire? Blast it with a garden hose and maybe flush it down. Compressed air....Also there is more access with the starter out. I haven't been there but it seems guys always find a way.

Kris smith

One of them thing man.

DFlintstone

I guess I might be careful there. I'm not sure if that could bet bound up in there while you are cranking it. Could get ugly. Idk. Btw because of the shoulder on that bolt the CPS may well be out far enough to read low.