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Unread 01-16-2013, 12:23 PM   #1
tml71
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1981 CJ7 Won't Start..Any Ideas?

I recently purchased a 1981 CJ7 with inline 258 6 cylinder that was in great original condition, but didn't run. So, I've installed a new battery and the engine cranks over fine, but I cannot get it to start. Here is what I've done so far:

Ignition - checked for spark from coil and its fine, checked for spark at each plug and they seem fine, checked timing and its set at 8 deg BTDC, checked to make sure rotor is firing to #1 cylinder when it is at TDC in compression cycle. As far as I can tell, ignition seems to be OK.

Fuel: hooked the fuel pump to a 5 gallon can with new gas, rebuilt carb, have verified that I'm getting fuel to the carb, can see fuel spraying in carb throat when pumping the accelerator. Not sure what else could be wrong here.

As I crank the engine, occasionally I'll get a little backfire through the carb, but then nothing again for the next 5 minutes of cranking. So I'm stumped. Could the coil just not be providing enough charge to ignite the fuel? Could compression be a concern (haven't checked that yet)?

I'm hoping someone out there has some wisdom to share!

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Unread 01-16-2013, 01:35 PM   #2
RamblingCJ
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I recently installed the Howell kit on my 258 and had similar problems. My jeep ran fine before the install, other than a crappy idle.

I had everything installed correctly and could not get it to do anything but an occasional high ping backfire. Had spark and fuel. Finally got fed up and replaced the coil. Sure enough while adjusting timing it fired right up.

Those coils can be quirky. They can test good but be going out. They're relatively cheap, that's why I bought one just to eliminate it when I was stumped.
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Unread 01-16-2013, 01:46 PM   #3
82JeepCJ7
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Pull the #1 plug, make sure the piston is at TDC on the compression stroke, and make sure the rotor is pointed at the #1 plug wire. Also double check the plug wires to ensure they are where they are supposed to be.
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Unread 01-16-2013, 02:28 PM   #4
draperjojo
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Quote:
Originally Posted by 82jeepcj7 View Post
pull the #1 plug, make sure the piston is at tdc on the compression stroke, and make sure the rotor is pointed at the #1 plug wire. Also double check the plug wires to ensure they are where they are supposed to be.

x2
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Unread 01-16-2013, 07:46 PM   #5
BagusJeep
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Check at the modue that you are getting battery voltage on the white wire in the 2 pin plug in Start.

This is the signal for the module to retard the ignition by 11 degrees, allowing easy starting.

If somehow you have adjusted the timing in Start with the module retarding the ignition.......... the only ways to time it is to physically turn the engine at rest until a spark is issued by the coil or dynamically at idle with the vacuum advance disconnected.
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Unread 01-16-2013, 08:09 PM   #6
Toad1987
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I have found that using those in-line clear spark checkers to be a good idea. The plug may spark when its out of the cylinder, but not when its int the cylinder. Reason is that when the air/fuel mix is compressed, the resistance or effort the spark must do to jump the gap also increases. Check you plugs also, if the center porcelains are cracked, ( had a set of plugs in mine do this) they will arc deep in the plug and the fuel mix will never ignite, ore if they porcelan is carboned or oil fouled, it also will have a difficult time igniting the mix. Check with an inline tester and if that is good, check the plugs. Also check the rotor on the distributor, seen one or a ford bronco a friend installed, he broke off the locator pin and the rotor stayed in one place when the engine was cranked, shouldn't be possible on this, check the bottom of the cap for carbon tracks.
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Unread 01-17-2013, 03:36 AM   #7
RWise
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How long has it been setting without running?
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Unread 01-17-2013, 04:35 AM   #8
Matt1981CJ7
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You covered spark and fuel. How about air? Is the choke working?

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Unread 01-17-2013, 05:42 AM   #9
Cherokeester
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I will bet you are 180 degrees out, your distro is firing on the exhaust stroke. Do what is mentioned above, check for tdc on compression stroke. Also, if your engine is not running, getting accurate timing is hard. Start at 0 degrees and retard from there. And again, make sure your spark is good.
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Unread 01-17-2013, 11:37 AM   #10
tml71
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Thanks for all of the great suggestions. I have checked the distributor timing relative to the #1 piston TDC and it looks fine...should be firing on the compression stroke as needed. So I don't think that's it.

Stopped by the parts store last night and picked up a new coil...figured it was relatively cheap and worth a shot. When I removed the old coil, the connections were a little rusty and I found that the positive wire connected to the coil was barely hanging on to the connector clip by a thread. So...major revelation! I fixed the wire connection, installed the new coil, and checked the spark from the coil again...much stronger!

BUT...went to start the CJ and it still wouldn't go. A few sputters on the first couple of cranks but that's it. After throwing a couple wrenches and shedding a few tears in frustration (Ok, maybe that was just the beer dripping down my shirt), I pulled out the trusty service manual (which I inherited with the non-functioning CJ7). I followed the troubleshooting steps for the ignition, starting off by checking the voltage at the coil with ignition in the run position. 6.6 V...as needed. I then had my son turn the key for the start position and checked the voltage as the engine cranked...bounced around like crazy from 0 - 12 V. The manual then led me to check the voltage at the starter solenoid where the positive coil feed to the coil connects, which also fluctuated during startup. Looks like I may have a short circuit in the solenoid which is reducing voltage to the coil as the starter cranks. So, the parts store ordered a new solenoid for me ($12...not bad), which should be installed some time tomorrow.

From what I can tell, it has to be the ignition system. Keeping my fingers crossed that this will do the trick!
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Unread 01-17-2013, 11:48 AM   #11
tml71
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Quote:
Originally Posted by RWise View Post
How long has it been setting without running?
It had sat for about 2 years without being driven.
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Unread 01-17-2013, 02:52 PM   #12
hp_lovecraft
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Quote:
Originally Posted by tml71 View Post
...should be firing on the compression stroke as needed. So I don't think that's it.!
A quick test is to swap all the wires on the distro. Meaning, swap #1 with #6, #4 with 3, #2 with #5.

If the problem was only you were not on the compression stroke... it will start right up.

I've made that mistake countless times... not that I'd want to admit it. Worst was 3 years ago when I had just upgraded my distro. WOuld not run. So, rebuild the carb... new plugs, wires, etc.. New vac lines, redid grounds, took apart distro... etc, etc.. I ran out of things to fix, and on a whim, I swap the wires and boom.. ran perfectly. darnit! I was positive I had the compression stroke, but was wrong.

At least if you try the test above, you can elliminate it if it doesnt help.
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Unread 01-18-2013, 02:54 AM   #13
RWise
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It wont hurt to swap the wires 180*, one never knows what the PO has done, and I know folks that set the dizzy 180* out!
Have you ran a compression test yet?
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Unread 01-18-2013, 04:08 AM   #14
86cj74.2L
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How old are the plugs. I've seen many plugs spark outside the engine but foul under compression. Expecially if it tries to start but never does.

Will it run on starting fluid?

What are your fuel mixture screws set at and what carb?

Have you moved your distributor around while trying to start it?
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Unread 02-01-2013, 08:54 AM   #15
tdesilet
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So tml71 did replacing the Starter Solenoid fix the starting issue?
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