White scout car stalls

[Rob Cassin]

Here is what another Gent said... Applies to many vehicles:

Rob,
Next time you stallt-pull the high tension lead out of the distributor and hold it near a ground-a cylinder head bolt usually works well. Make sure all the paint and rust are cleaned off the bolt head. If there is no spark, the bolt may not be well grounded(rust on threads,etc.) so clean off something else and try the spark test again. Hold the lead about 1/16" away from the ground. An ignition in good shape can usually spark up to 1/4" gap.

Vapor lock occurs when gas in the fuel system(carb, fuel lines, and fuel pump) gets heat soaked-i.e. the engine is hot and gets shut off. There is no movement of fuel so it sits there cooking away. Eventually it gets so hot that it starts to boil and floods the engine. The problem is much worse these days because the gas has ethanol in it which has a much lower vapor pressure so it vaporizes at a lower temperature than gasoline. To clear a flooded engine, hold the gas pedal down at full throttle and crank the engine over. Eventually it will suck all the raw gas and gas vapor thru the engine and start. Don't pump the gas pedal because every time you pump the pedal the carb squirts a shot of gas into the engine.

It's been my experience that vapor lock rarely occurs when driving because the gas is cool going into the carb and passes right thru and thereby cools the carb. Air is also being blown by the carb and intake manifold by the fan and road wind which also keeps the intake system cool.

Usually it is an ignition problem. The condensor in the distributor can go bad gradually and it will short out when it gets hot. This keeps the ignition coil grounded so it can't produce a spark. The ignition coils can go bad also. There can be a break in the internal coil wiring but the wire ends are still touching, or the insulation between the coils can go bad. When the coil heats up, the wire expands and wire ends at the break quit touching or the insulation breaks down so the spark jumps from coil to coil with the end result of the coil not working. Let everything cool down and it starts to work again.

It might be easier to install new points, condensor, coil, and spark plug wires. Other than the coil, the other stuff is really cheap and it is basically just a tune-up which the truck probably needs anyway.
Hope this helps.
Dennis

[Mike K]

Be cautious of using the new replacement recently manufactured condensers , even the supposedly good quality BOSCH brand ones don't last that long in service. As a general rule they should be around .025uF capacity. I sometimes see the old condenser testing sets at swap meets . The condenser is dealing with the primary low voltage circuit but from memory the primary voltage kick back can be as high as 300 Volts across the condensor, this is something to do with the collapsing field across the primary windings in the coil collapsing at a faster rate than when the field is growing .

[Rob Cassin]

Hi Mike, Could you recommend a brand? and where I can get one? Thanks, Rob

[Lynn Eades]

Rob, my suggestion would be to buy a Pertronix with one of their coils. No condenser in the system and pretty trouble free. You would also need to go away from the copper H.T. leads.
I agree with the lines of thought already presented.
Most likely a coil or condenser as running for 15 minutes it is not likely fuel (other than the blocked vent)
Do a careful job. Everything matters.

[Rob Cassin]

Hi Lynn, Thanks for your help. What has me confused is when it happens, I pull the coil wire from the distributor, and check the spark and it is good. So I am thinking it is the fuel vapor locking, but I really like your Pertronix recommendation. It can only help it run better. Thanks, Rob

[Lynn Eades]

Hi Rob, can you "jerry rig" a fuel supply that by passes direct to the carb and try that? (do it carefully to be safe) That should isolate the problem one way or the other.

[rob love]

Bypassing the fuel system may be a good idea. I had an M37 Dodge that acted similar to what you are describing. Turned out there was the body of a bug or fly in the fuel system that would get caught in a brass elbow fitting. When the engine would die, he would slip back a ways in the fuel line, only to eventually come back into the fitting on the next run.

Another option would be to crack the fuel line to the carb when it happens and see if there is fuel. Or, after it stalls, you can simply pour a little fuel into the carb and see if the truck runs on that. Some gasoline into a hand oiler will do the trick and limit the fire should things go awry.

[Lynn Eades]

The hidden shuttle valve Rob.