even so the choke/pumping technique should do it, even at times when the cranking was reasonably strong

My thinking was if the carb was getting a bit iffy the air/fuel mix in cold weather wont be right, thus the difficult/no starting.

You guys sure nothing else about the carb is suspected?

I have tried partially and fully closed chokes but they dont seem to help :(

Sight glass level is slightly above the dot in the middle

I know this is more of a general carburetor-engined issue but perhaps the lot of you Datsun owners can shed some info on this.

1981 B310 with the stock A12A motor and Hitachi DCG306 carb. In warm weather, 1-2 pumps of petrol will get the engine fired up no problem. In cold weather (especially overnight rain), the engine would crank but that's about it; no chugs no blips no nothing.

If I try to pump more petrol, one of two scenarios may occur:

1) The engine still doesnt respond
2) It splutters a little due to slight overflow/flooding.

When (1) happens, I'd still try cranking but nothing would happen. If I pump more petrol a third time (or fourth or fifth because the engine STILL doesnt respond) it would splutter tremendously due to excessive flooding, an indication that I might as well take the bus.

When (2) happens, I'd crank it a couple more times. Sometimes the engine would start, sometimes it wont. If I try pumping a little more, the spluttering continues in a never-ending cycle, or if I'm lucky it will start.

I'm pretty sure the problem lies somewhere in the carburetor, but my dad suspects the ignition coil isnt making enough voltage for the spark plugs.

But then again I do notice my battery is significantly weaker in colder weather and the cranking isnt as strong. When I give it a jump start the engine would start almost all the time. I seem to understand that the weaker battery would cause the following (please correct me if mistaken):

- Slower cranking leading to weaker compression in the cylinders; air/fuel mixture doesnt burn properly

- Less voltage going to the ignition coil and finally to the spark plug; weaker spark doesnt ignite the air/fuel mixture

So... your thoughts please?

I've inspected the carb and I found the following:

1) The needle valve is squeaky clean
2) There's residue at the bottom of the chamber (presumed normal?)
3) When I gave the top cover a few taps, sand/dirt/grit poured out from the fuel inlet pipe
4) The float level was too high (about 6mm clearance at the top compared to the 12mm specs) but was later adjusted.

Could #4 be the cause of it?

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gonna have DIY time then (I have two soft copies of repair manuals) . thanks dennis!

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Mine isnt electric. And even if I did have an electric pump my original carb would be overflowing too because both carbs are the same model

alright, I'll give it a look when I'm free. Are there any other possible causes besides the needle and float?