So the auto has started doing this recently as well - recs absolute fine without load, and if you squeeze the throttle she is ok (Ish) but if you plant your foot she wants to stall (or does)Bug wrote: ↑Mon Mar 28, 2022 12:13 pm I think the rich fuel smell is the giveaway here.
Too much fuel getting into the carb so when you accelerate and it adds even more then its moving the mixture outside of a combustible range.
However, if the above answers don't cure it then this is also a classic symptom of a failing accelerator pump diaphragm.
When you push the throttle down, the flap opens which suddenly dumps the low pressure by reducing the venturi effect (Check out Bernoulli's Theorem). Therefore the carb temporarily cannot suck the fuel through the jet.
The accelerator pump exists to cover this temporary loss of low pressure by firing fuel straight into the carb mouth.
If you open the throttle slowly the engine is able to keep up and keep pulling the air through fast enough to create a low pressure area in the carb, thus sucking in fuel.
The accelerator pump is basically a diaphragm with a big spring behind it. The spring forces the diaphragm across to allow room for a small reservoir of fuel to accumulate behind it.
When you push the accelerator open a long way, the linkage acts on a plunger on the other side of the diaphragm, overcoming the spring and pushing the diaphragm across, forcing the accumulated fuel out through a jet into the carb mouth.
If the diaphragm splits the fuel just nips to the other side of it and doesn't squirt in.
Simple check. Take of the air filter, look down the carb and open the throttle right up. Don't need the engine running. You should see a squirt of fuel.
On the assumption that you have a 32/36 DGAV fitted then there is a Y-shaped nozzle below the choke flaps. If the carb came off a lower spec (GL or similar, you may well only see fuel squirt into one barrel as the other side is blanked off. On a 'S' model, it should squirt into both barrels.
You may also have a blocked Y-nozzle. Simply remove the top of the carb, undo the screw in the middle and lift it out to clean it. Beware there is a very small ball bearing underneath the nozzle body, which acts as a valve to stop the carb sucking fuel through in normal operation.
Probably not your issue, but always handy to know a bit more about how the carb works.
I have checked points, timing and spark etc. So tried your trick earlier of looking down the carb - very interesting, you can see the first side squirt fuel and then if you keep going the second jet starts squirting too (interestingly the new (probably fake) Weber on the laser doesn't do this by I digress) - but the big hesitation when you plant your foot still occurs. It's almost like it's taking a deep breath and then tries to hold it for a few seconds before actually deciding what to do.
What is the best course of action? If this sounds like an accelerator pump I will look to change it, but to me carbs are the dark arts and I can just about get to grips with where air goes in and fuel goes in