What is wrong with my Jeep? Please help!!!

Just a note - if you haven't done this before sometimes the spark is not easy to see, especially if it's a bright sunny day. You sometimes really need to get down there with your eye near the spark plug gap to see the spark. Put some shade over it so you can see the spark.

I've made this mistake a few times where I did have spark but didn't see it. Then went off on a wild goose chase to find a problem that didn't exist.

As mentioned, if you don't have spark you can work backwards through the system. Plug, plug wire, distributer cap, rotor, points, condenser (small coil inside distributer), wire connections, coil, ignition switch, battery/alternator, etc., etc.

I once had trouble because of a bad connection at the main engine wiring harness connector near the passenger side valve cover.

 

Could be the float is fuel logged and flooding out the engine. It's easy to check-remove the top of the carb and pull the float pivot pin and put in a can of fuel and see if it floats.

 

OK, at the suggestion of some of the folks on here and some friends where I live I replaced the points condenser and coil resistor. Afterwards it started up fine again. I drove it around the neighborhood, put it back in the garage idling, and about 10 minutes later it died again and wouldn't start. So we've ruled out the fuel pump, fuel filter, ignition coil, ignition resistor, and condenser. Any more suggestions? I'm still thinking its a temperature-dependent spark problem of some sort.

 

Wiggle the ignition switch and see if it changes. Had the switch go bad and would work fine then not.
Check the wiring inside the distributor and make sure all is good, not touching ground, etc. Have had wires break inside the insulation. Check grounds between the chassis, engine, and body. Make sure they are clean and tight with good connections.

 

So when the motor dies, what does it not have? Spark? Fuel? Other?

I guess what I would do is try to test for what's not there when it quits. Could be an electrical connection that heats up and expands to lose continuity. So like nickmil said, check that out.

You could also pull the top off the carb to see if the float bowl is full of fuel or if it's empty.

Just brainstorming.

 

Your timing light is a good diagnostic tool also. Connect the inductive coupler to your coil wire to the dist cap. (connect other two leads as usual to battery) Run the connections under the hood opening so you can hold the gun and observe while cranking the engine or running it. Say your getting the gun to flash but engine won't start, you put the inductive coupler on a plug wire. If no flash at this point then you know your loosing the spark in the rotor to cap or not firing at proper time. Also could be center of rotor carbon tracked to ground, etc.

 

The engine needs 3 things to run.

Very loosely stated, they are;

Fuel, spark, and compression.

The fuel system starts at the vent hole in the tank/cap, and ends at the intake valve.

The spark system starts at the battery, and ends at the engine block.

Dont worry about compression---if it aint there, you would not be getting it to run nohow.

Both fuel and spark systems have areas where heat can cause problems------

IMHO, I am leaning a bit toward a fuel issue.

Good luck, this is a rough one to chase down, hopefully you get sooner than later.

 

OK, I think I'm getting somewhere. THANK YOU ALL FOR YOUR HELP!

I have been checking the spark from the coil to the distributor. How fast should this be sparking? It's going about twice a second. It doesn't seem like a lot, but I really don't know what i'm talking about, so it could be just fine. I called the auto parts store and they were more clueless than I was. They were confused by the points.

So, is twice a second enough?

If it is enough, and its an electrical issue, its narrowed down to the distributor and downstream.

 

Its cooled down now. I have it running again and the spark through the coil-to-distributor wire is almost constant (checked with timing light).

When its dead and I'm trying to start it, its about twice a second (cranking).

I'll wait for it to die and check the distributor-to-plug wires for spark next.

 

OK, with it running I just checked the distributor-to-plug wires.

Some of them have a regular flash on the timing light. One of them is dead until I rev the engine, then it takes off, most of them are irregular, but flashing.

So, it appears that could be my culprit.

What could cause that? Bad distributor? cap? wires?

I think I'll wait for it to cool down completely and try it again. I'm guessing all of the plugs should be firing regularly and somewhat evenly.

 

Engine Ground?

 

The distributor breaker plate (the plate the points are mounted on) rotates back and forth by the vacuum advance. This means it has no solid connection to ground so a wire is fastened to the plate and then to the distributor housing. Your pic of inside of dist showed it being rusty. Make sure both ends of the connecting wire have a good connection and the wire itself is not broken as it flexes a lot.

 

I was where you are a few weeks ago with my F-134. The shot gun approach to problem solving left me where I started – with a dead jeep. The key to getting her going was to approach it systematically. I found that I had more than one ailment contributing to the failure. I recommend that you first establish a good spark all the way to the spark plugs, then attack the fuel delivery. Even if fuel delivery is the cause of the engine not running, the engine will benefit from the improved spark.
Having said this, there are a few things I would do before tracing the spark from the battery to the spark plugs. These are predicated on the fact that most of your symptoms appear when the engine is idling or running at lower rpm’s.
WEAK BATTERY AND ONE-WIRE ALTERNATOR OR BAD REGULATOR
If your alternator is a GM wired as a one-wire, then the alternator usually does not put out until after the engine has been rev’ed up. In my jeep, it took a good rev’ing to excite the alternator. I could run the jeep at top speed and the alternator would not turn on unless I had rev’ed it good. When killing and restarting your engine several times a day, it is easy to forget to rev the engine each time. The net result is you are running on the battery and the alternator is not recharging anything. I had this problem. After idling a while, it would just die. You can test this by rev’ing the engine and confirming that the alternator is putting out by checking the voltage meter in the dash board. If your battery is already shot, the engine might still die on idle even if the alternator has successfully been turned on. Solution: replaced battery and rewired the alternator as a 3 wire. Even if the charging system is ok, you might want to swap in a good battery and see how she runs. I don’t understand why but sometimes a poor battery affects engine performance, especially on idle.
POOR GROUND FOR DISTRIBUTOR
Sand the gunk off the distributor clamp and the engine block. I did this along with cleaning the dirt off the coil and my spark improved significantly.
VENT THE GAS TANK
If the tank is not vented it can create a vapor lock which an idling engine cannot overcome. Take off the cap and see how she runs.
Good luck. There are a lot of good ideas from the various posters. Just do it systematically. Also, I found that making an under the hood starter switch saved an incredible amount of time and effort.

 

i dont know if it was mentioned but could be vapor lock in the fuel lines. My dauntless exhaust was awefull close to the lines so i made a thin aluminum shield and screwed it right to the frame where they were close. That could be your problem especially if your not moving and idling

 

I had a mechanic look at it today quickly. He adjusted my points (they were far too close, apparently). He also checked the give to the belt and said my timing chain was off and should be replaced. I have it idling now to see if it dies again or what with the points adjusted.

 

how did he check the timing chain? just curious

 

Put trans in neutral. Grab the fan belt with both hands and rock the engine back and fourth. The crank will turn pretty easily until the chain tightens against the cam gear. If you can rock the dampner pulley back and fourth to get an estimate on the degrees of slop. I change mine before it gets 20-25 deg slop.

 

Exactly what he did. I have about 30 degrees. I'm going to try to limp through the rest of this season and replace the chain and gears this winter.

 

I see the possible vacume pipe. its in the same location as the hole you are showing us but on the front of the carb. check to see if its pulling vacume.(put your finger on it while its running, mabe rev it up a little). look for a hose that may have came off.
I would look at heat issues also. oh and it looks like you have point ignition. points needing ajusted or replace would make it stall out, and run rough. been there and done that.. good luck. 69 cj5