1978 - 124 Fuel Problem

[Naples124]

I recently tuned up my carburated Spider because it was running rough at low speeds and difficult starting, even after just sitting a few minutes it was also stalling at low speeds and was very rough running at low speeds but fine above 3000 RPMs. After replacing the fuel filter, both sets of points, condensors, rotor cap and plugs/wires - it ran about the same. The carb was rebuilt last year and I also replaced the fuel tank because of rust issues. This problem is new so I was looking at my see-through fuel filter and noticed that fuel ran freely when running but when the engine was shut down the fuel drained from the filter so there was nothing in the bowl at start-up. This leaves me to think that the mechanical fuel pump is the problem - what do you think?

The pump is original and the car has about 53,000 miles on it. The pump looks like a bugger to get to so I want to be sure this will fix the problem. Another option may be to leave the mechanical in place and add an electrical pump in the trunk. Any ideas if has someone run into this before?

[So Cal Mark]

even if the filter drains, the carb bowl will not

[Naples124]

Thanks for the fast reply! Yes, the engine will turn over but will not catch, I am assuming that the gas in the bowl is empty by then and no gas is flowing to the carb up from the filter. I just started it back up and after some pumping and a couple of false starts, it fired up. Again I saw fuel flowing while the engine was running, just barely seeing gas in the bottom of the filter. When the engine is shut off, no gas in the filter. I thought in the past I would always see the filter about 1/2 full of gas?

[So Cal Mark]

no matter what happens with the filter, fuel will still be in the carb

[manoa matt]

That pump is actually pretty easy to get to, there are only 2 bolts. I would first replace all the rubber hose sections on the supply and return lines from the tank to the carb. Keep looking as there are many small sections hidden along the drivers side rocker panel. There is a small one way valve in the fuel tank vent line. The valve is located up over the rear axle, remove that valve and replace the vent line with new vinyl tubing.

Is the fuel pump the original Savara brand? Somewhat gold in color and crimped together? Or is it a replacement that can be taken apart with 6 screws around the perimeter, or just one big phillips screw on the top? If its the one with the big phillips screw on top, that can loosen and let the fuel drain out, just tighten it.

With a proper functioning pump and lines, the fuel will not be bubbling as you observe it in the clear fuel filter.

[Naples124]

Matt, I can just barely see the pump but it looks like it may have been goldish silver but it is a casting (aluminum?). As for easy to get to , without a lift I am not sure I can even get a hand on it from the bottom and no way it's coming out the top! I didn't mention that the car has AC (non-functional at this point) so maybe the AC pump is in the way now. Do these symptoms seem to point to the fuel pump or am I grasping at straws?