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Discussion Starter · #1 ·
\'77 CJ7 engine help?

Can someone help me here?

My 77 CJ& inline 6 258 cid was driving along happily with me, when it decided to cut out. A few minutes later it decided it was ready to restart. I had this problem once again, and then it was fine for a half hour or so. Then two short blocks from my house, the Jeep decided to go belly up on me. At an idle, it was a little rough when it was running with some backfiring. I had just rebuilt the carb, replaced fuel pump, and I checked to make sure it was getting gas. I then checked to see if it was getting electricity, and hooked a timing light up. Nothing came through the timing light. I have a prestolite point type distributor, I have tried replacing the ignition coil and ignition module and I have not cured the problem. Can anyone tell me what is going on, or what to look for? I am about to hit a brick wall here, because I cannot figure what is going wrong. Please help me!
 

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Re: \'77 CJ7 engine help?

Check for vacuum leaks in both the lines and the carb itself.
 
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Discussion Starter · #3 ·
Re: \'77 CJ7 engine help?

Would the vacuum be causing no spark to go through the distributor?
 

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Re: \'77 CJ7 engine help?

I would almost venture a bet that you have a broken wire (green) between the coil and the ign module. Check for a good consistent 12 volts at the coil (red). If that is OK, then examine the green for a break that is barely touching some of the time. Don't forget, this wiring is 22 years old.

CJDave
 
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Discussion Starter · #7 ·
Re: \'77 CJ7 engine help?

Take a look at my post on your other question.

Brad (from the 4 Wheeling center of the universe, 4 corners USA)
 
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Discussion Starter · #8 ·
Re: \'77 CJ7 engine help?

Okay, I still need help. I have checked the coil, had the ignition module checked, replaced the rotor, replaced the distributor cap, checked the green wire from the module, and made sure there was 12 volts from the ignition circuit to the coil. Still, I am not getting a spark. The only electrical thing left in this circuit that I know of, is the pick up coil in the distributor, can this be causing a no spark condition out in my distributor? How do I check it? Any other ideas? Can this be a grounding problem for part of the circuit (i.e. my fender is not well attached to the frame and the iginition module and start solenoid are mounted to it).
 

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Re: \'77 CJ7 engine help?

OK< Try this.....take coil wire out of dist cap....take cap off dist....turn on ign switch...grasp the rotor and turn it back and forth so the little "star" wheel passes the pickup module back and forth. The coil should throw spark to the engine block if it is within 1/2" of the metal.

CJDave
 
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Discussion Starter · #10 ·
Re: \'77 CJ7 engine help?

I'm a little puzzled here. I believe it is mentioned that this is a points-type ignition. But, an electronic ignition was stock for 1977. Having owned a couple of '77's, I have become aware that the system used in 77 was troublesome. I once bought a 77 with only 20K miles on it. When I bought it, it already had a replacement ignition module (the unit on the fender-well), and the factory-original module was in a box, under the seat. By the time that the vehicle got to 25K miles, the second module had failed. I installed another new module, number three, and verified that I had found the correct problem. But, also, I went to my friendly parts manager at the local dealership, and asked about the problem of the failures. I was told that the system in 1977 was very troublesome, and that a different system was introduced in 1978 (and the 78-up system has a better record). So, what I am saying here, is that if it is a 1977, with factory electronic ignition, beware of problems. At the time, I found the 77 module to be about a $100-item. The symptoms you are describing could be from a dying module, or a dying (coming-apart) pickup coil in the distributor.
But, you said points.... So... you are describing the same symptoms that come from a dying condenser. And, I also am well aware of this, because I put a points-type system on my 77, and the first failure that occurred, came from a dying condenser (that I had used from a salvage yard). This is an 'under-$5' try. And, while you are about it, be sure the points are opening properly (or replace them), and the distributor shaft is not loose and causing variable point opening.
Bob

bob
 

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Re: \'77 CJ7 engine help?

Actually, BBK, we have determined that it is a breakerless ignition, as furnished stock that year, so the things you describe could apply. There is a lot of brain power focused on this 304 right now.

CJDave
 
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Discussion Starter · #12 ·
Re: \'77 CJ7 engine help?

Ok.... What my 'dealer-parts-friend' indicated to me was that I should consider switching to a different system. I believe he meant 'newer', like perhaps 78-up. Best wishes.

bob
 
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Discussion Starter · #13 ·
Re: \'77 CJ7 engine help?

I thank everyone for their help on this, I have picked up a new pick up coil (it is an electronic distributor) and I will install it when I get home next Thursday and let you know how it worked out. It has got to be the solution as I have had everything else checked out or I have checked it out myself. What were the upgrades to the '78 is that where it switched from a Prestolite distributor to a Ford?
 
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Discussion Starter · #14 ·
Re: \'77 CJ7 engine help?

I shudda thought of this before, and this should be a 'no-brainer'. It seems like now is the time to consider the HEI conversion. There are numerous references regarding the HEI, using one from a 76-80-ish Chevy 250 in-line 6-cyl, either internal or external coil. This will offer reliability, long-term parts availability, and better performance. My .02

bob
 

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Re: \'77 CJ7 engine help?

You said you have a point type distributor. Did you replace the condensor? That's what makes the spark hapen if I'm not mistaken.

P.S. I don't think points were used in the stock '77 Jeeps. You may have an older distrib. and even engine.

Loose nut behind the wheel
Another right-wing conservative.....
 
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Discussion Starter · #17 ·
THANK YOU!! Re: \'77 CJ7 engine help?

After all that, it was the pick up coil. It had loosened up and the spindle had worn through the coil housing to the wire. Once I dropped in the new one and spliced in the leads, it started right up. Thank you to everyone who helped!

Dave
 
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