spins but wont crank......driving me insane!!!!!

[jamie83cj7]

Hello all, long time reader, first time posting. I have an 83 cj7 that has caused me more gray hairs in the last month than my 9 year old!! heres whats going on, followed by what ive done.... the jeep 80% of the time will not start by turning the key. Starter engages, engine spins over just fine. you can kill a fully charged battery trying to start and its not gonna happen. 20% of the time, about the time im gonna give up, VROOM!! Ive put in and tested since, a brand new battery, new plugs, new wires, cap, button, fuel filter, all the "normal stuff for a tune up" and still not cranking. It will "roll off" just fine, ive even jumped it off with cables a few times and it fires right up. Ive verified spark, compression, and fuel. Im starting to think its somewhere in the ignition. Last summer i noticed that it would fire as i let go of the key. i can hold the key and it will spin and spin, but as soon as i let the key go it would fire up. kinda shrugged it off because it always started. Well now its not lol. When it does start, its when i let off the key. Ive been thru this motor several times in the past, along with several others, so i feel like ive covered all the regular "wont start" problems. Definitely open for suggestions though. Im completely clueless on the ignition side of things. anyone have any ideas?? thanks in advance.....JT

 

[roughrider]

I would definitely look for bad wire connection first. ignition switch next. am going thru similar test now

 

[jamie83cj7]

I've checked my battery and ground connections. All look good. Next thing I'm gonna try is to start it by jumping the starter. If it starts that way it pretty much tells me it's in the switch correct?

 

[greg92jeepxj]

Verify ignition coil positive post is hot in CRANK and START . This will tell you if there is a fault in the ignition switch on the steering column. A test light will be suffice.

 

[69jeepcj]

This sounds like a failing ignition switch. As said above, check voltage at positive side of coil while cranking the engine over, should see 12 volts on the meter. check for loose connections at the ignition switch. Since it does start when you let go of the key, kinda sounds like the problem is in the switch.

 

[jamie83cj7]

Thanks for the replies fellas. I'll definitely be checking voltage at the coil. What I can't wrap my head around is why it jumps off so easy. I mean with cables. I understand why it would roll , but when I hook it up with cables it fires right up! I never liked the "horse shoe" connection on the coils. I want to convert over to an hei distributor, but being a single dad of 2 it's not a priority right now lol. Raising 2 girls is tough!! Haha

 

[jamie83cj7]

ok, fully charged battery. key in the on position im only getting 9.3 volts to the coil. ill check again while trying to crank.

 

[Dragon5126]

A quick point of info: Just to give you a bit of info on terms to give you a hand in the future to save confusion: SPINS this is the action of the starter alone " the starter spins but doesn't crank the engine" this means the starter isn't engaging the flywheel to turn the engine. CRANKS: the starter engages the flywheel and turns the engine. These may sound petty, but are very important differences. One indicates a mechanical starter problem the other an ignition or fuel delivery issue. Back in days of Yore when I was 15 the Drivers Ed program drilled basics like this into the students before we were even allowed behind the wheel. Simple terminology like this can save you from dealing with mechanics out to take advantage of you, who would throw an expensive starter in to the repair just because "you said..." Granted you came here where nobody is out to take advantage of you, but you never know what the future may bring, and knowledge is power.

 

[jamie83cj7]

thanks dragon, i do understand what your saying, but in my original post i state that the starter engages, and the engine spins over. hope i didnt confuse anyone.

 

[69jeepcj]

Ok, so your getting 9.3 volts.. not enough! I think it could be either the coil or ignition switch. my vote is to replace the coil first since it is the simplest and if that's not it, I would replace the ignition switch. I pretty confident one of these two is your problem.

 

[jamie83cj7]

Thanks 69jeepcj. I'll start with the coil. I'll post back in a day or so once I replace it.

 

[jamie83cj7]

I put a new starter solenoid on yesterday and the Jeep started right up. I figured maybe that was it. WRONG, it drove like a top for about 15 mins then started sputtering. Made it home and parked it. This morning it wouldn't start so I jumped it off. Again, ran like a top for about 25 or 20 mins and started sputtering again. Could this be caused by a bad ignition coil? I've read a little about "heat sink". As I stated in the original post, I'm not exactly clear on how that coil system works, but as I've read I've seen where if it's not producing the correct voltage to send for spark it does affect the performance while driving. The cap and rotor are brand new. Solenoid is brand new. Is this starting to sound more like the ignition coil that the ignition switch? I will replace the coil this afternoon for sure. Any advice before then is appreciated.

 

[superj]

if it started after you put the coil in, then you wiggled something that is the problem. go out and wiggle those particular wires again and see if it starts. if not, wiggle some other stuff near there. it sounds like you have a bad connection somewhere, now

 

[jamie83cj7]

I didn't mess with the coil, just replaced the starter solenoid. I'm gonna replace the coil this afternoon. Getting an excel ignition coil. I hate the horseshoe connection, but I'll make sure they are connected well. Hate throwing new parts at it, but it can't hurt anything except my wallet lol.

 

[JPNinPA]

Being you had to jump it is your battery or altinator in good shape? You might want to have them inspected.

How is your engine temp after 10 min? Before and during sputtering?

 

[jamie83cj7]

JPN, engine temp is good. Before the mis hap yesterday i put the battery on charge. When i put it in the jeep it was turning over fine, just wouldnt start. Alternator checks out, after i put a starter solenoid in and got it running, i checked the battery. It read 14.1 volts. Just went and bought the accel ignition coil on my lunch break. I will put it on before i leave the shop today.

 

[superj]

did you ever take the starter and get it tested on its own? i didn;t read if you did that, or not?

 

[jamie83cj7]

No sir superj, the starter seems to turn the engine fine. If this new coil doesn't do the trick, I'm gonna replace the key switch. If I'm still having trouble I'll look at the starter. Thanks for bringing that up. Hadn't thought about it.

 

[jamie83cj7]

UPDATE! put the new ignition coil on, bumped the key and VROOM!!!! hopefully that clears up my problem!! thanks for all the tips and advice, ill post back after i drive it around.

 

[greg92jeepxj]

Well , as it turns out , the ignition coil was the weak link. I was thinking to approach this step by step to verify actual voltage response from both the RUN and START ( cranking ) at the coil positive post to eliminate or isolate a possible fault there before moving to the secondary ignition . Wanted to be sure the coil was fed properly from the ignition switch in both positions . The next test would have involved the coils high tension lead to the distributor for output . Inspecting the coil tower and distributor tower for carbon tracking , inside the cap at the tower post and rotor button as well. It seems the old coil didn't have the current flow to give the extra hot spark to the cap for starting as needed but well enough to run. Obviously a weak coil which necessitated replacement . Glad you got it running without spending a mint . Thanks for sharing the problem and solution . Step by step in detail. Will no doubt be helpful to anyone whom shall ever need to diagnose a similar fault . Also , thanks for your membership here at jeepz.com .