A1 still not running right

Beast · Post by **Beast** » Sun Jul 22, 2012 8:57 pm

I have not been able to figure out what has been causing my 53' A1 to run really ruff and backfire. This was a condition that came about without any changes made to the Jeep. But it starts fine and runs good for a minute until it starts to warm up. Then it begins to run really ruff and starts backfiring through the exhuast. When you pull the spark plugs they are all black with heavy soot. Even a new pair did it right away and came out black and sooty. I have checked the spark, fuel delivery, the diaphrams in the carb, adjusted the float level, and compression in all cylinders. I adjusted the timing and that made no difference either. I even tried to cheat it to see if it is a fuel delivery problem by closing the fuel valve near the fuel pump part way to restrict the amount of fuel being delivered to the carb and all that did was seam to make it continue to run ruff until the bowl ran too dry and stalled out the motor. I guess that leaves me into the electrical parts. I have tested for spark on all wires with no problems. Has anyone ever had a coil go bad that still delivered spark, but maybe not a hot enough spark for the plugs to burn all the fuel completely? I don't know, I've usually had it where, once a coil goes bad that it just didn't work at all (no spark).

Anyone got any other sugjestions or had similar problems? I'm starting to run out of options to test things.

Post by **wesk** » Sun Jul 22, 2012 11:10 pm

First remove the gas cap and then try running the jeep until it warms up. If it now runs smooth then the culprit is a plugged vent valve on the tank and/or the fording valve inside the cap is in the closed position.

Once you make this easy check and if your problem still exists then remove the coil and check it with an ohm meter both cool and hot enough to make it uncomfortable to hold in your hand.

Beast · Post by **Beast** » Mon Jul 23, 2012 11:48 am

Thanks, I'll check the coil with an Ohm meter when I get the chance. I'm sure it's not the gas cap, as that would put vacuum on the fuel system which starves the carb for fuel. My problem is running rich, to much fuel for the motor to burn cleanly.

Post by **wesk** » Mon Jul 23, 2012 12:07 pm

Soot on the plugs is not always a rich indication. I would still check the cap and tank vent. Soot is often present when the jeep is not run but a few minutes. Do you have rolling black smoke from the tail pipe?

Beast · Post by **Beast** » Mon Jul 23, 2012 2:44 pm

No black smoke, nor any smoke from the tailpipe, but a heavy fuel smell. I'll try it with the cap open to see, what the heck it can't hurt at this point to check.

Beast · Post by **Beast** » Mon Jul 23, 2012 6:23 pm

Opening the gas cap made no difference, but closing the fording valves (pulling the lever out) did seam to make it run slightly better. It would sit and idle, but still backfire once you gave it gas. I was able to drive it up and down the driveway,(it's a very long driveway) and get it into second gear. I ran semi-decent as long as it was not under a load, the second it got under a load it would backfire and act up. The hotter and longer it ran, the worst it ran. I ordered a new cap, rotor, and coil from John at Midwest today and I'll put those in once they get here.

Post by **wesk** » Mon Jul 23, 2012 8:24 pm

What were the ohm readings on the coil?

Beast · Post by **Beast** » Mon Jul 23, 2012 8:33 pm

I haven't taken them yet, but order the spare parts so that they are here the next day that I'll have a chance to work on it. That way if the ohm readings are bad I'll have the parts ready to install, if not I'll file them away for the next project.