Won't start after sitting

[smithdc]

have 79 spider and it runs fine and starts up right away after a short rest but when left sitting overnight or longer will not start
Put a touch of gas in the carb and she started up and ran fine even started after short stops but leave it for few hours and no go, cranks just fine took a plug out and it was dry so it is seems to not be getting gas when trying to start??
Was idling erratically at the first of the season had the carb set up and checked the idle solenoid and it is working and it seemed fine for a few weeks now this?
suggestions

[So Cal Mark]

you may have a leaking accelerator pump diaphragm which allows the fuel to leak from the float bowl, leaving an empty carb.

[smithdc]

accelerator pump are we talking fuel pump or in the carb
itself?

[smithdc]

sorry after reading your reply again we are obviously talking carb
sounds like time for a carb kit

[smithdc]

Quick question should the fuel pump not pump fuel into the carb as it is being turned over?

[So Cal Mark]

the fuel pump should pump fuel while the engine is cranking but it can take extended cranking to fill an empty carb. A weak fuel pump may not pump fuel at cranking speed, but work adequately when running due to the difference in rpm. Make sure all of the hoses from the tank to the pump are good, otherwise the pump doesn't create any suction. This isn't your starting issue though. The carb bowl should hold enough fuel to start and drive a few blocks

[smithdc]

thank you

[smithdc]

was also told to replace the check valves to the carb one may be faulty

[bradartigue]

Whoa now...

The fuel pump and the accelerator pump are not the same thing. The fuel pump is what brings fuel from the tank to the carburetor. The accelerator pump is a device on the carburetor that gives a squirt of fuel when the throttle is in transition. It is a square with a circular diaphragm and spring inside. It can be serviced without removing the carburetor.

When the accelerator pump is old it allows fuel to leak from the bowl into the venturi; overnight it will drain your carb into your motor.

If you have an original FIAT check valve remove it and replace with a new hose. The FIAT check valves were recalled around 1980 because they leak.

[So Cal Mark]

I guess I wasn't clear enough in my response. Thanks for clarifying

[bradartigue]

I guess I wasn't clear enough in my response. Thanks for clarifying

I felt a disturbance in the force, like a rebuild was coming in when it sounds like a little diaphragm was all needed.

[aevansgatech]

It is a square with a circular diaphragm and spring inside. It can be serviced without removing the carburetor.

On Weber carbs is it the small square part with the actual Weber letters on it? Located on the side closest to the drivers front tire

[bradartigue]

It is a square with a circular diaphragm and spring inside. It can be serviced without removing the carburetor.

On Weber carbs is it the small square part with the actual Weber letters on it? Located on the side closest to the drivers front tire

Yes. It has four screws, it says "WEBER" usually around it, and has an arm that goes underneath it to a roller. The roller sits on a cam. When you rotate the throttle the roller moves on the cam and the pump is activated. Simple device. Unscrew the screws, remove the spring and diaphragm, spray it out with carb cleaner, replace the diaphragm and spring (in the correct order).

[sgkent]

does the choke close when the carb cools down?

Checked for vacuum leaks?

[AriK]

When the accelerator pump is old it allows fuel to leak from the bowl into the venturi; overnight it will drain your carb into your motor.

If this symptom exists but the engine does NOT buck on acceleration, is this still the sign of a bad accellerator pump? Hoses and lines to the tank are new and tight so no air is being sucked in from anywhere.