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I have a 1972 911 with an 1982 3L engine with Webber 40 IDA carbs.
Went to start the car the other day and it wont start! I have spark, timing is correct, electric fuel pump is working, i have pressure (and pulled off pipe at carb and fuel squirts out when ignition on). I took off the top of carb and jets are all clean, float is working and there is fuel in the float bowl.
When i press the throttle i can’t here the normal hiss from the fuel spraying. When i looked inside i’m Just getting a dribble from the accelerator pump (arrow) and nothing from the jet that sprays into atomiser (circled).
Not sure why this isn’t working? And am totally stuck! Any ideas?!
Fuel will not spray out of any carburetor unless the accelerator pump is actuated very briskly.
Webers MUST have precisely 3.5 psi of fuel pressure so thats something to check.
Starting a Weber-equipped car from cold requires several pumps of the throttle to get gas into the engine. Remember, there is no choke nor cold-starting circuit.
Thanks for your help so far. Throttle linkage and throw are fine. Not even getting spray when I quickly depress throttle at carburettor. I have the right pressure (see below) isn’t stock set up. I have an electromotive distributor where I can adjust timing etc. All was working fine last week. And I have checked I’ve got power there.
I'm unable to see your pics, but I can tell you that if your carburetors are old, the accelerator pump diaphrams may be cracked or damaged and that will prevent them from working properly.
owned the car about a month. Was running a week ago and seemed totally fine. I jacked it up at the back to adjust clutch cable and replaced all the bushings in pedal cluster. Then tried to start while back was in the air to check clutch cable and wouldn’t start. And haven’t been able to start since.
Troubleshooting no-start issues requires a careful and methodical approach to be successful. Carbureted cars require a specific skill-set and experience with carburetors to understand how they operate in order to find out whats wrong.
I've always began the No-Start process by thoroughly eliminating the ignition before working on the fuel system.
This means that one ensures a nice blue spark (using an extra one grounded while cranking). Then, I make sure its occurring at the right time, no matter if its a DIS system or a distributor. In this case, I would double-check the adjustment **** settings.
Check the fuel pressure at the carb inlets to make sure you have 3.5 psi.
Looking down the carb throats, pump the linkage to make sure each accelerator pump is squirting fuel into each respective throat. Sometimes the ball check valve can stick and prevent this from happening and the car will NOT start from cold.
Never assume ANYTHING!!!!!
Remember, if you have a good spark (at the right time), if you have fuel into the carbs, and if the cams haven't jumped time, the engine will start.
06-18-2018, 05:38 PM
3L engine Weber 40 IDA carbs wont start!
