Carb or pump?

[rasouth]

Last week I went to start my '78 and it started okay but would not idle. After a few quick adjustments I got it started. The next day I tried to start but would not idle. I decided to rebuild carb. It had some grit in the bottom of the bowl so I cleaned and blew out all passages, checked jets and put it back together. It will start but still will not idle or idles real rough and then dies. It revs fine but will die right after I release the throttle.
I noticed that the fuel filter got about 1/3 full and after I let the car set for about ten minutes the filter is empty. I could not find any leaks in the lines.
Could this be a bad fuel pump (mechanical) or did I mess up the carb somehow?

[kilrwail]

This is going to sound really dumb...but check your ignition points. If they close too much due to vibration or whatever, the symptoms would be similar. Ask me how I know.

[Zachary]

How do you know?

[rasouth]

Timing is good, points are good, all plugs firing.
The car was running good when it started all this. I drove up to my buddy's house, spent a couple hours working on his "69 bug and when I went to start up the car would not idle. I played around with the idle screw, got it running and drove home with no problem. The next day I started it up, rough idle, drove it around the block, ran rough. I thought it was just a clogged-up carb, but now... IDK.

[1976sport]

Ignition, although all these carbs seem bad even when they work. If you take the car up to 65 or so what happens?

[majicwrench]

Still probably a plugged up idle circuit. The idle/slow speed jet is TINY and plugs easy. Not sure what kind of carb you have on 78, but my 72 the idle jets are on BOTH sides of carb near the top underneath a brass screw. Remove screw, jet often, but not always, comes out with screw. On my car at least, they do not come clean unless removed and cleaned. Ask me how I know. And if you have an idle soleniod on 78, that has to be "clicking" when you unplug/plug in wire, and the soleniod has to be energized when you blow out idle passages, or it will block the passages you need to clean.

[rasouth]

The last couple of times I had it up to 60-65 it ran okay. It just suddenly stopped idling and ran rough. But with the fuel filter getting maybe 1/3 full and after about ten minutes the filter was empty I'm thinking something might be wrong with the fuel pump

[rasouth]

BTW...I have the 32 adfa carb.

[majicwrench]

It is NOT the fuel pump, it is not unusual for filter to be only partially full, and that does NOT indicate a problem. It takes a LOT of fuel to go 60mph, and almost none to idle....so if car can go 60mph, fuel pump is OK.
http://www.google.com/imgres?imgurl=htt ... s%3Disch:1

Item 45 is idle jet

[rasouth]

If pump is okay then why would fuel drain back out of filter after engine is turned off? Could pump diaphram have a hole in it?
I remember pulling idle jet out and blowing with air but maybe I didn't get it all.

[majicwrench]

PUmp has rubber valves that keep fuel from flowing back into tank. All it takes is a tiny bit of debris under valve and they can let fuel drain back. THAT IS NOT YOUR PROBLEM. The problem that can come from fuel draining back is loooong crank times if the car sits for looooong times and the carb bowl goes dry.
That idle/slow speed circuit, to get clean you need to yank idle solenioid, mix adj screw, and idle/slow speed jet. Make sure idle soleniod works, should click when power is applied.

[rasouth]

I do have to crank the engine for a while after it has sat for a few days. I'll leave the fuel pump for another day.
The solenoid does click when key is on and I pull wire and re-connect.
Thanks for the advice. I'll re-check the carb.