Engine not starting

[thistle3585]

Here is the order of events, I drove my Jeep home and decided to track down a wiring problem with my left turn signal not working. The Jeep was running then all of a sudden it died. It would not start after repeated attempts. It is getting fuel, I replaced all the plugs and tested them and am getting a spark. I have been having trouble with it over the last week or two. I have had to drive it with the manual choke fully engaged, but I'm not sure how much of this is due to the cold weather. It has struggled some when accelerating. It would hesitate and miss out. It turns over and occasionally will catch for a couple rotations then it dies. So, now I'm trying to figure what direction to take with it before having to be forced to take it to a shop. Any suggestions?

 

[BusaDave9]

Important question: does the starter motor turn the engine?
Is this a problem with the starting system or the ignition system?

If the starter cranks the engine but no spark I would start out by checking the small red (or red and white) wire on the coil when the key is on. You should have 12 volts there or you have a wiring problem. That could also be a problem with the ignition key switch.

 

[thistle3585]

I had put the Jeep in my shop at work for about a month where I replaced the steering column, the steering shaft, rear main seal, oil pan gasket and valve cover gaskets. During that time, I also had the starter rebuilt since I had it out, so it works fine. I drove it for about two weeks before this problem. I'm wondering if its the distributor or possibly the wiring in the new column.

 

[cerrajero]

can you post a pic of the "new" column ?
and did you use your old ignition switch or the one that came with the column ( guessing you got a used column)
and your T-150 Transmission is manual right?

 

[thistle3585]

The column matched up fine, had come out of another '79, and everything worked. I replaced the column because the ignition had been pulled out of it and the ignition was installed on the dash. I wanted it back to original.

I did go out and check the coil and I was getting power to it. I did notice that it was very warm to the touch. I'm wondering if the coil is shot?

 

[BusaDave9]

I did go out and check the coil and I was getting power to it. I did notice that it was very warm to the touch. I'm wondering if the coil is shot?

Could be. Check the resistance. you should have 1.13 to 1.23 ohms on the primary and 7700 to 9300 ohms on the secondary.
(NOTE: my resistance numbers are based on my manual. The numbers in the diagram are vague and refer to most any car)

 

[thistle3585]

Well, it has gone from bad to worse. I installed a new coil. It still wouldn't start. After an extended period of cranking I saw sparks fly from around the battery and/or solenoid. I'm not sure which since I was in the Jeep but I'm thinking it came from the battery. Does that indicate a short? I'm thinking I'll need to take it to an auto electrician.

 

[thistle3585]

I put the old coil back in, tested it and it is fine. I think the auto store gave me the wrong coil. I did replace the wire module on the top as it was in pretty bad shape. I can get it to sputter a few times but it wont run. It is getting plenty of fuel. My next thing is to test the ignition module. I'm going to take it to an auto store for testing. If that comes back good then I'm not sure where to go next.

 

[BusaDave9]

If it was running and suddenly died it sounds like a wire has a bad connection. I don't think the ignition module is bad. You need to use a volt meter or test light to check some voltages. Start with the small red or red and white wire on the coil. You should have 12 volts there when the key is on. See if you loose the voltage when you wiggle wires. Have someone wiggle the wires under the dash that head to the ignition switch.
Are you sure you got the spark plug wire on right? Fireing order is 1,5,3,6,2,4

 

[thistle3585]

The red wire at the coil, with the key on, is 6V. I am guessing that my next step is check where that wire comes from the ignition switch? Which wire am I testing?

 

[grozam]

Fuel pump could be weak. That was the problem with mine when i first got it. It would have to be choked to run and didn't want to rev. but would idle.

 

[thistle3585]

I can't imagine it being the fuel pump because I can't get it to start by pouring gas or starter fluid in the carb. I can see fuel squirting in to the carb when I press the accelerator.

 

[BusaDave9]

6 volts at the coil. That's not good. It should be battery voltage. Double check that your battery has 12 volts and then we need to track where it goes low. May be a bad connection. may be a short drawing it low.
Do you have an in-dash volt gauge? What does it read. Check 12 volts elsewhere such as the fuse panel. Does it looks like you have 12 volts everywhere except the coil? That same 12volts should be going into the ignition module on the fender.

If you think you have a good 12 volts everywhere EXCEPT on the ignition system next step is to disconnect the positive on the coil. Also disconnect the ignition module and see the 12 volts comes back. If not we need to trace down where the voltage drops.
12 volts should go into the steering column (red wire) and to the ignition key switch. Then when you turn the key to run 12 volts should come out the ignition switch. This will be a red and white wire. Actually there are 2 red and white wires coming out the ignition switch. One goes to the fuse box. The other goes through the big bulkhead connector and on to the coil and ignition module.

EDIT: this wire marked TACH is the wire that goes to the coil and ignition module.

 

[thistle3585]

Mine was wired like the one pictured below which is a later version. As I understand it, the wire coming out of the tach goes to the ignition coil. As I mentioned earlier, I had driven this for some time without issue. I'm wondering if the PO had rewired it and it finally took a toll on something. I'll go through it some more tonight and see what I can come up with.

Here's a thought.... Can I bypass the ignition system by running a wire from the battery to the coil to get my 12 volts so it will start? My dilemma is that the Jeep is now sitting outside in the cold and if I could get it to my work then I could have it inside to work on. I just didn't want to pay a tow truck to haul it.

 

[BusaDave9]

I had driven this for some time without issue. I'm wondering if the PO had rewired it

Yes, that makes me think this is a wiring issue. Bad connection or a short. It could be that something went out such as the ignition module but I don't think that's as likely.
I keep thinking the problem is the wires to the steering column and ignition switch.

Can I bypass the ignition system by running a wire from the battery to the coil to get my 12 volts so it will start?

Yes, you could do that as a test and a temporary fix.
The problem is you must remember to remove that wire when you leave the jeep sit for more than 2 hours or your battery will go dead.

 

[grozam]

Yes, that makes me think this is a wiring issue. Bad connection or a short. It could be that something went out such as the ignition module but I don't think that's as likely.
I keep thinking the problem is the wires to the steering column and ignition switch.


Yes, you could do that as a test and a temporary fix.
The problem is you must remember to remove that wire when you leave the jeep sit for more than 2 hours or your battery will go dead.

You can put a switch on that wire so you don't have to disconnect it. and just switch it on when running the engine.

 

[thistle3585]

Spent more time in the cold tonight. I have full voltage at the ignition switch and the tach. I also have voltage coming out of the ignition module on the fender and going in to the wiring harness which feeds the engine compartment. So, somewhere in the two feet between the ignition module and the coil I am losing half my voltage. What I did find is that there is an additional splice at splice F, which is on my Hayne's drawing page 10-22 section A3, that leads to the solenoid. That wire show the same six volts but there is a third splice, not on my drawing, that goes to a plug attached above the oil sending unit. I recently swapped out my electrical oil pressure gauge for a mechanical one, so I replaced the oil sending unit with the mechanical setup. The old purple wire for it is still hanging there. Could this be causing that drain? What would the plug be? What is the difference between an oil pressure sending unit and an oil pressure switch? I have to believe that it has to do with that.

 

[CJB4POWERBILL]

Just dealt with this same spark flying no start two days ago. After checking everything under the sun, turned out to be bad ground cable from battery to block. Cable looked totally fine , I just so happened new one in shop and slapped it on. Viola, fired right up. For giggles I put old back on and same no start sparks flying ....just an idea

 

[CJB4POWERBILL]

Classic sign of bad battery cable is volt meter shows 0 when key to start position but if u roll key back to "acc" and volt meter on dash shows 12v..u prob got bad battery connection. Just thought, that's all input I got on this one, as I'm a greenhorn at his first day of school. good luck brother

 

[thistle3585]

Well, I think I have found the problem. The orange wire that is spliced from the ignition module to the coil had heated up and melted the jacket, along with the wires beside it, and there was a couple bare spots in it. I cut a section out to take with me to the autoparts store and noticed the jacket says, "resistor do not cut or splice" Is this a special type of wire and does it have to be a certain length?