jeepsnhondas

hey i recently bought a 93 jeep cherokee 4.0 high output 150k miles clean title for 400$$

thing is it doesnt start the guy i bought it from said one day it just didnt wanna turn on anymore he changed the crank position sensor coil pickup rotor distribuitor and spark plug wires and still didnt start so he just wanted to get rid of it

towed it to my house ive bin trying to get it to start but it just keeps cranking n cranking it doesnt even backfire or anything but it has spark and fuel wat can it be??? shouldnt it atleast backfire or something since it has both spark and fuel? please help thanks

RTorrez1

You said that you have a weak spark. That can be the whole problem. You need a strong blue spark for her to fire. I would also check the fuel pressure at the fuel rail with a mechanical pressure gauge.

jeepsnhondas

what would cause weak spark??

jeepsnhondas

please help thanks

jeepsnhondas

the guy i bought it off of said he thinks its like an auto shutoff sensor or something like that that prevents it from starting he said its by the shifter under it or something like that??

tjwalker

1. As mentioned, you need a strong BLUE spark to start the engine. Yellow/orange/white indicates a weak spark, which may not be strong enough to start the engine. The primary cause of weak spark is a weak ignition coil.

2. Verify fuel pressure. This MUST be done with a fuel pressure gauge. I know you said you have fuel, but you must achieve a minimum fuel pressure to start the engine. For your 93, that is approximately 31 psi.

3. If the above two things check out (and only if), then run a compression test on all cylinders. Never rule out the possibility of an internal problem. The compression spec. for the 4.0 engine is 120-150, with no more than a 30 psi variation between cylinders.

jeepsnhondas

even if it has the fuel pressure isnt right it should still atleast inetnt to start with starting fluid right???

jeepsnhondas

if the coil is weak should i just go buy a new one? the guy i got it from had changed it already he said and yea it has red spark so that means its weak spark? wat else can cause that

jeepsnhondas

anybody????

xj guy

I was going through a similar problem today. What I would do to start off is check your fuses in the engine compartment. In my 96 the box is located on the passenger side right by the battery. In there, there are large fuses, mini fuses and relays. The back cover of the box should have a diagram of what goes where. Check all fuses to make sure they are good.

As you mentioned before you think the PO said something about the ASD (auto shut down relay). There are relays located in this box too. Use that diagram mentioned above to locate the ASD. Notice the part numbers on that one and temporarily switch it with another with identical p/n.

These are just ideas. it doesn't sound like your problem, but it is way easier and way faster to check these since you don't need anything but your hands and eyes.

Let us know what you find.

jeepsnhondas

i checked all my fuses from engine fuse box and under the steering wheel all fuses are good my fuel pump is turning on i have spark but its red and i keep reading that red/orange is WEAK SPARK that it needs to b blue wich means strong spark wats wrong with my jeep i need help please im in modesto ca if anyone close can help me ill pay $$$$ but im really hoping that the motor isnt bad since it atleast has weak spark it should atleast try to start atleast backfiring or something right???

xj guy

Have you done any kind of searches on what could cause a weak spark? Are all of your plugs giving you that weak spark? If so check back further or simply replace your plugs and wires. Is there anything wrong with your ignition coil, cap and rotor? Remove it and do some testing on it. I did pulled my coil the other day and followed instructions from the haynes manual and it proved that it was still good. Have you gotten your battery LOAD tested?

And don't mean to be a D-bag but try to use some punctuations. Makes it a lot easier on the brain.

jeepsnhondas

im going to change the cps tomoro morning and ima take the coil to autozone to seeif they can tell me if its good idk wat else it can b im stuckkkkk

xj guy

Before you go and do those things PLEASE go out and buy an OHM meter. I had no idea how one worked until this weekend and I'll tell you I could have saved myself about 8 hrs had I of listened to it. I bought a cheap one for $2.99 at HF (yes I know its cheap). But PLEASE listen to me. Otherwise You'll kick yourself for work you did but didn't need to do.

http://www.jeepforum.com/forum/f11/h...-4-0-a-803463/ Read that thread about how to test it. It will save you some time. And I also believe that if the CPS was bad that you would not have spark (don't know for sure though).

Then you can also check the ignition coil with the multimeter as well. If you are going to go to the zone for parts PLEASE pick up a manual. It will be your best friend. And you really just need to have some patience man, I know its frustrating to have a no start for a car especially after you take car of a vehicle. But throwing parts at it isn't going to make it work. Diagnose it first.

Basically this weekend I had a stall out and then a no start. Would crank and crank but not turn over. Had fuel at the rail and no spark. Everyone and their brother said CPS. Bought a multimeter and tested it and it said it was still good according to the test. But being an ignorant 21 year old I replaced it anyways. Didn't fix my problem. Went to the ignition coil (which everyone then referred me to) pulled it and ran test on it with the meter. Meter said it was good but again I was an ignorant young gun and replaced it anyways. Still no start. I then checked my fuses (should have been the first thing I did) and it was a little 30 mini amp fuse. Replaced it and it was fine. But I could have saved myself all that time had I of listened to my own tests. (I returned the parts for my money back and put the old stuff abck in now that I can replace both within a half hour...). Basically get a multi meter and start running some tests dude. And also, if you don't use at least three punctuation marks in your next reply you won't hear from me again!

jeepsnhondas

hey i got it runnning just wana let u guys know what the problem was incase anyone goes thru this

i figured it would b a ground because it had spark good coil good cps it was just weak spark theres 3 grounds coming from the wiring harness that go on the side of the block by the dizzy and those grounds come from the coil

1 of those 3 grounds was broke off from being to old i guess put it on and started right up thanks for the help!!!