Need to know why fuel in glass filter bubbles

[nibbes123]

Is it normal for the fuel to have bubbles in the filter while idling and when car is off the filter has no fuel in until you crank the engine over. Also while driving today after 1/2 hour drive the car started to jerk and strave for fuel but kept on going sometimes would jerk again , kept the RPM at about 3000 80klm anhour. Any idea if the fuel pump is bad, not an electric pump.
Thanks
Nick

[kmead]

It is pretty normal to have air bubbles in a gas line, especially a low pressure gas line to a carburetor.

The bubbles are unlikely to be the issue with your drivability. I would look at your carburetor as the issue or ignition system HV circuit.

You don't provide information about the year and equipment on your car but the following are likely things to look at.

First the carb should be clean and properly set up, which would include setting the float level as well as ensuring all of the jets and so on are clear and clean. I would buy a rebuild kit and go through the carb that way with new seals and so on.

The next area I would look at is the ignition system. The first thing to look at is general condition, wires, cap, rotor, points, condenser and so on. I would replace the spark plugs, I have always had good luck with NGK copper plugs, not fancy but good, solid reliable plugs. Sometimes a coil can be damaged by leaving the ignition switch in the on position which overheats it and can cause stumbling, it can be checked using a multimeter. A bad condenser can cause a wide variety of different odd symptoms, replacing one is cheap, easy and quick. You might consider changing to an igniter which can get rid of most of the problematic parts, there is also a unit from 123 in the 400 dollar range which is a direct replacement for the head mounted distributor and of course Mark has an excellent unit which is block mounted like the early 1438 engines.

If you have a Fiat OEM electronic ignition the pickup and associated wires can and do fail. A replacement is quick but a bit expensive.

[danaspider]

It would be interesting to know if you still have a mechanical fuel pump or eletric. I have seen problems over the last 30 years where with the mechanical pump being used and a really hot day you can boil the fuel, enough to cause vapor lock.

So let us know a few more specifics on the year and configuration of the car.

[nibbes123]

Hi guys
My car is a 1978 1/2 124 spider with OEM electronic ignition , 32/36 DFEV carb with mechanical pump 2 litre block with matching head. Car ran great with new carb for 1 1/2 year but started to act up know. Hope this info helps.
Nick