Studder/stall after driving

[Tim Smith]

This is so annoying. I've been tuning up here and there but this problem has me stumped.

The points are freshly cleaned with a little bit of sand paper and well adjusted. I've opened up the carb (Weber 34 ICH) and didn't find any debris. All in all the thing idles just perfectly around 700 rpm, until I go for a drive.

Driving along, sometimes I can feel it missing. When this happens and you hold the throttle and rpm at just before overrun (not really accelerating or decelerating) you can feel the motor bucking and missing. When that bucking condition happens I know that it will stall out when I get to the next stop sign. If it doesn't stall out then it will be running terribly as I'm two footing it to keep it going.

When it does stall out, I'll restart it and it will run perfectly again. Well until I start driving it again.

Any thoughts from the group?

[kevin-ct]

fuel filter? if you need help I can stop by this weekend.

[Tim Smith]

You might be on to something Kevin. I do have one ready to pop in and to tell you the truth, I forgot about it...

Thanks!

[Andrew IIA]

You need driving gloves !

(private joke for tim), A

[Tim Smith]

Neck and neck, battling up the hill. Sweat beading off my forehead. Smoke barreling into the cabin. My passenger leaning into it, gesturing the shear madness of it all. Up comes the next bend and I'm sure I'll have this one. Gearbox whining as I'm quite possibly squeezing every inch of torque out of this thundering block. It's a blind turn heading our way and this race of chicken is at full tilt. I glance over to Andrew hoping steal that look of fear and desperation that I'm surely conveying at this very moment.

What do I see? Oh nothing special. Just Andrew calmly down shifting and perhaps reaching for a sip of tea (little finger raised). His dogs looking at me from the back as if I'm giving them a show.

You may have beaten me this time Andrew, but next time I'm wearing driving gloves.

[ktom300]

Try your condensor. Mine was flaky and no matter how much I sanded the points I couldn't get it to run past idle.

[adkrover]

Try also to clean the inside of the cap and the contacts of the cap and rotor. If they are caked with gunk that can make a weak spark of if there is a lot of carbon floating around in there it can cause the spark to arc across to a different plug. Really plays heck with a proper firing order.

[Jeff Aronson]

This happened to me once; check your hose from the air cleaner to the carb. If the inside is loose it will close up under the pressure from the carb intake. Try running the car without the hose.

Are you sure you don't have water in your gas? Have you removed the fuel pump sediment bowl to check for water? That would cause the same symptoms as you're describing.

The condensor is a good tip also. Try replacing the current one with your old one [they rarely go "bad"] but I've also experienced similar symptoms with a bad condensor. It's the only one in 19 years of Land Rover ownership, but there you go.

Lastly, when this happens again, feel the coil. It should be warm but not hot to touch. A coil breaking down inside will also produce the bucking under load, but the car will often start fine for a while.

Let us know what you find.

Jeff

[Wallace]

I had a similar problem with my 109 on a trip from RI to VA. Every now and then, it would miss and die at speed only to restart and run fine at idle. Sounds like fuel, right? I replaced the filter, blew out the lines and disassembled the carb - all at the side of the road. Several times, in fact (CT, NY, NJ, MD). The points, condenser, cap and wires were all new, but proven. I checked them all anyway but couldn't find an electrical problem. Eventually, it died completely and had to be towed the last 8 miles. Embarrassing, but I had run out of ideas.

The fix turned out to be quite simple. The short ground wire inside the distributor (the one that grounds the points to the distributor housing) had a break inside its fabric covering. It ran fine at idle. But when the vacuum advance started rotating the plate, the ground wire would change position slightly and the points would lose their ground.

Might be worth checking.

[kevin-ct]

Hey Tim, Did you find the cause?

[Tim Smith]

Hi everyone,
These are all great thoughts. I haven't had time to actually look at the truck yet but am planning to figure it out tonight. Hoping to get this fixed and ready for my next road trip starting tomorrow night.

I'll be sure to post up the details of my findings.

[kevin-ct]

Tim, if you need help I can stop by tonight.

Road trip, where?

[Tim Smith]

Hey Kevin,
If you are up for it, shoot for 6:00 pm as I should be well into it by then.

I'll tell you all about the beer run too.

[Tim Smith]

So it's not the fuel filter, carb, wires cap or plugs. Not the points and not the fuel pump.

I've had to quit for the night but I'm going to check the condensor and that little ground wire tomorrow.

I did take it for a drive and at least I've got the timing and carb set up right. Good power (under throttle even if it's acting up) and no pinging. As a test, I drove it until I could feel it acting up. When I would come to a stop sign it would either die or run terrible.

However, if I knew it was running badly and I was coming to a stop, I flicked the ignition off and on again real quick just before coming to the stop. When I did that it ran beautifully! Tried it a couple of times and it seemed to do the trick. Does this sound like a condensor? I have to admit that I need to read up on that little piece of kit.

[SafeAirOne]

So it's not the fuel filter, carb, wires cap or plugs. Not the points and not the fuel pump.

I flicked the ignition off and on again real quick just before coming to the stop. When I did that it ran beautifully! Tried it a couple of times and it seemed to do the trick. Does this sound like a condensor? I have to admit that I need to read up on that little piece of kit.

The function of the condensor is to briefly give the electricity someplace to go when the points open. If the condensor wasn't there "absorbing" the electricity when the points opened (or was defective), the electricity would just spark across the points even though they were open. This arcing would have the same effect as the points staying closed. That is to say that the magnetic field around the primary winding in the coil would never collapse and energize the secondary winding, which drives the spark plugs. End result: the engine won't run, or won't run properly.


Condensors are cheap. It couldn't hurt to replace it. After that, What's left? The ignition switch, the power wires to the ignition switch, the wire to the coil, the coil, the primary wire to the points, and the points ground.

EDIT: A fairly decent description of the ignition system component functions can be found here.