I can't get the old Duster to stay running after a few miles. I leave town and get up to 60 mph and a couple miles down the road it starts to stall and sputter. Although if I coast for a while and the bump start it goes no problem for about 100 feet. It then stalls again, but when I get back to town at 30mph it does just fine. I have replaced the fuel filter thinking this was the problem, but it still happens any ideas?

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I never dreamed about success I worked for it - Estee Lauder

Float would be my first guess. Check the adjustment.

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Casually looking for a Clifford hyperpak intake for cheap.

If it has points, check the gap. It could be closing up as it warms up. If it has been converted to electronic, then check the gap in the reluctor. It will do the same thing.

Sam

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Sounds like it is running out of fuel at speed when engine is under load when its fuel needs are higher. In other words fuel pump is not delivering enough volume of fuel for whatever reason: defective pump; plugged line on suction side of pump somewhere all the way back to filter sock in tank, or perforated fuel line on suction side of pump dropping its ability to deliver full volume.

As mentioned above float level may be too low disallowing enough reserve in bowl to keep up with high demand. This is a quick check so do it first than dissect fuel line condition back to sock.

One more thought just entered my atrophied brain; look for plugged tank venting. A tank's plugged vent would allow fuel pump to pull a vacuum on tank, and once that vacuum comes close to pumps ability to pull, fuel flow stops. Try driving with filler cap lose and see what happens, or when engine stops, jump out and crack filler cap open and see if it sucks in air.

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67' Dart GT Convertible; the old Chrysler Corp.
82' LeBaron Convertible; the new Chrysler Corp
07' 300 C AWD; Now by Fiat, the old new Chrysler LLC

Ok I have checked the float and everything seemed ok, but the radiator seems to be leaking. It is leaking on the side next to the fan and was smoking seems like I have to replace it. I am wondering since obviously my temp gauge isn't working could this be the reason the motor is stalling?

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I never dreamed about success I worked for it - Estee Lauder

If it is running really hot it may just be vapor locking. is it boiling over and overheating, any coolant in it? Even with out a gauge you'd know if you cooked it..

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66 A100, 64 356C

I believe it may have, because of the steam rolling off the radiator. There was a good amount of fluid on the side facing the fan.

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I never dreamed about success I worked for it - Estee Lauder

Vapor locking is very rare when the engine is running so I suspect that is not it. First suspect is that you have a bunch of crud in the fuel tank and it is blocking the fuel tank pickup sock. It can be partly blocked when you start and then you pick up more crud on the sock as you drive at high speed and it finally blocks up completely. Stopping for a bit allows some of the crud to fall away and you are OK for a bit. Slow driving will slow the fuel consumption and the sock may not be plugged enough to stop enough fuel flow to casue it to run out a low speeds.

Check the charcoal canister being plugged by just removing the canister line going back to the tank and then drive it. If the same symptoms persist, put the line back on the canister.

Check the fuel pump by taking off the line to the carb and putting it into a contaner; then crank the car and the pump should pump roughly 1/2 pint in 30 seconds. If so, then move on to the tank as the issue.

You can use low pressurized air back into the fuel line to blow the sock off the pickup and if this cures it, then your tank is full of rust and crud and NEEDS to be dropped and cleaned and perhaps replaced. This is a common issue on these cars.

These are great old cars, and worth fixing up. First things first is to get the fuel, or whatever figured out. Don't forget the fuel filter itself. All this advice has been good. Then figure out your cooling system. Try to get a real read on the actual temp. I have a real temp gauge on mine. It should hang between 180 and 200 in normal operation. This can make a big difference. If the radiator is clogged, you will need to deal with that.

How are the brakes? They are probably the next priority after fuel and cooling system. What ignition is on it now? I assume it has a points ignition unless someone has changed it. They work OK but need maintenance to keep them working well.

Sam

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True, crud could cause these symptoms, and is a very strong possibility.

That's a pretty ingenious test, but it gives me shivers thinking about how quickly a bunch of crud could get sucked into the line. Then you'd have an even bigger problem to clean up (or replace all the fuel line.) Since the car reportedly starts sputtering after only a few miles, would you consider the test a success if it ran 5 miles farther than usual? What if the gunk clogged up the filter, wouldn't it still sputter out? I'm not sure the results would be reliable enough to tell you much. Maybe, but maybe not.

By the way, is this car in the rust belt, such that replacing a fuel line (and all brake lines) would be a good idea anyway? In that case, go ahead and perform whatever drastic tests you want. All the other suggestions have been great, it's only this one that gives me pause.

The resulting advice, however, is spot on. Given the age, I would just drop the tank first, without messing around. If you've never dropped a tank, it seems daunting, but assuming it's mostly empty, the job is really not that hard. Flush it out well, optionally seal it with POR-15 paint (they make special gas tank repair stuff you just slosh around inside til it dries), and if there's any doubt about structural integrity (too much rust), just replace it.

Gas leaks are not just annoying, they could be fatal. Do some research on the Ford Pinto, among others.

- Erik

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Lots of early Valiants and Barracudas have crossed my path.
Also a handful of other toys for variety now and then.