Engine Starts, Immediately dies...HELP

[tim843]

Just bought a 78 CJ5 AMC 304 V8 3speed and has started and driven fine for 2 weeks. Right after reinstalling the speedo cluster (not easy and couldnt avoid disturbing alot of wiring sliding it in) and testing gauges, dash wiring and fuse box with a light tester and meter, the engine turns over and starts, but immediately dies. It's always started no problem before. When I pulled out the aftermarket Sunpro fuel gauge mounted under the dash, it touched the dash and sparked. Checked fusebox and replaced cluster feed fuse and panel lights fuse. Also replaced the coil with a new one. Still won't stay running. What could I have disturbed or blown up that would cause this?
Thanks,
Tim

 

[mylittlecj5]

check the ignition switch and the solenoid. you may have burned one of them up when it sparked.
Does the ignition switch power up everything its supposed to when it is in the 'ignition' position?
The soliniod gives the coil 12v when the switch is in 'start', so it would fire the engine in start, but not in the 'run' position.



Disclaimer: your CJ might be new enough that the soleniod doesn't give the 12V to the coil, if so, I'd look at the switch.

 

[CJ]

As ML said, put the ignition in the run position and check to see if you have 12v at the coil. I'm betting you don't and burned up a fuse (or maybe a fusable link) to the coil.

 

[tim843]

The ignition switch does lite up everthing it shoould. Where is the ign solenoid ur talking about? Thanks

 

[CJ]

The starter solenoid is on the RF fender - that isn't your problem as the engine cranks and starts.

You say it 'lite up everything as it should'. This means you checked for 12v to the positive side of the coil when the key is in the run position?

If you have 12v to the coil with the key in the run position then there are other problems.

If you have 12v to the coil in the run position, disconnect the coil wire, keep your meter on the 12v side of the coil and have some one crank the Jeep. Then relase back to the run position. The 12v should stay.

Let us know.

 

[tim843]

Let me give you some test results.
With multimeter on coil positive(+) and good ground:
Key off: 0
Start 9.0v
Run 1.0v

I tried this test from the chiltons AMC 72-85 book. I tested coil to distributer cap wire pulling it off at the dist cap, placing it 1/2 " away from a good ground, result, got spark when trying to start ign.

What does this tell you guys?

I live in Louisville, KY and am so anxious to get this solved, I'm working on it on Derby Day when I could be at Churchill Downs right now!

Thanks,
Tim

 

[CJ]

You have a blown system link to the coil at the run setting. You should have 6v (yet you have only 1v in the 'run' position) (you have a ballist wire).

Back track the coil + wire using your meter (with the ignition switch in the RUN position) until you find the break in your voltage. It really sounds like you shorted out your ballast wire for the coil.

 

[tim843]

I see 2 wires on the coil (+)...a red with black stripe and a black that turns into a green w/black. Which one should I back track?
Thanks

 

[dslywalker]

Here's a wiring diagram pertaining mor to a 78 CJ
Mike

 

[CJ]

Back track both and all on the + side of the coil.

 

[TDHofstetter]

One of those two wires at the (+) side of the coil will go to the starter solenoid - that's the one that WORKS. The other wire leads back through the harness to either a physical ballast resistor or a length of special resistance wire. That resistance wire is probably your culprit.

I can't say for sure, but I've got a strong feeling that the green/black wire is your resistance wire. Cut the harness open to expose it - if it's the resistance wire, it'll be pretty short - maybe a couple of feet at most, probably folded up. Try hanging your multimeter at the other end of that wire with the ignition switch turned just to "RUN". You SHOULD see 12V at the far end and 6V at the near end (where you now see 1.0V).

 

[tim843]

First thanks to all who pitched in to help. Found the problem(s). The aftermarket fuel gauge I mentioned that sparked when I pulled it out seemed to cause the low volts in run position. It was mounted on a steel plate and screwed in to the radio opening. I screwed it back in (which grounded itself to the dash) and thats when it starts then dies at 1volt in run. I've since taken it all the way out (after I disconnected the battery this time!) capped off those wires. I've also pulled open the dash and found 3 wires melted together! Pink 16, green 18 and red/white. All 3 go from the connector under the dash that the steering column wires connect to, up and over the steer column, either out the fire wall or in the fuse box. Ive cut out the bad sections of ea. wire and getting ready to splice in new wire. Any tips?
Thanks again for everyone's help,
Tim

 

[TDHofstetter]

Tips on the splicing? First... use barrel-type splices - DO NOT use wire nuts. I hate those dang things - they're fine for house wiring with solid wire, but they're not worth a spit for automotive (especially Jeep, in the weather) purposes with stranded wire.

Next... DO NOT use the clam-shaped crimpers, the stamped steel ones with a little cup ground into each of the "jaws". Instead, do yourself & everyone after you a big favor & go to your local electrical-stuff place to buy a pair of real Thomas & Betts crimpers (commonly called T&Bs). They'll have one red handle & one black handle. They're inexpensive... and they do an EXCELLENT job of crimping barrel-type wire terminals. They've got one deep cup-shaped jaw and one nipple-shaped jaw that fits into the cup, so they make a horseshoe-shaped crimp.

Don't crimp all the wires at the same length - stagger 'em so the splices aren't all in one cluster.

Wire tie 'em together with BLACK (zipper-type) wire ties. The black ones last a lot longer in direct or reflected sunlight.

 

[coldwater]

A little wisdom, sorry it's too late. Allways pull the power cable when doing a cluster swap.