Carburettor Diffcult starting
Difficult starting problems with Carburettor
Often with cars fitted with a Carburettor, problems can be easily solved here we explained problems and how to find and fix them.
10 Common starting problems with Carburettors and fuel.
- 1 No petrol in float chamber because tank is empty.
- 2 Failure to switch off an anti-theft device which works by cutting the fuel line or electric pump feed from the tank.
- 3 Fuel pump not working or not working effectively. Note that an electric pump will beat rapidly and continuously if the tank runs dry and so indicate the cause of the trouble.
- 4 Filter gauze choked. The gauzes are normally found in the petrol unions on the carburettor; electric pumps have the filter in the base of the pump.The filter gauze in a mechanical pump is under the dome and can be removed.
- 5 It is possible that the fuel in the tank has become contaminated, maybe by vandals using such items as sugar or other substances clogging feed lines.
- 6 For cars not used after few months standing idle may have allowed the fuel in the tank to absorb water from the atmosphere, enough to cause trouble but this is unusual but depending on climate where you live maybe the problem. The tank and fuel lines will need cleaning out in such events.
- 7 In SU or Stromberg carburettors, it is possible for the jets to be blocked or to contain water, but this is unusual. For cleaning instructions, see Check the SU and Stromberg carburettors as well, but make sure the piston isn't jammed in the chamber by utilising the piston raising pin on SU carbs and on Stromberg’s to make sure the throttle linkage is operating the throttle and the operation of the choke. The inlet manifold has drains so that any gasoline drawn into the manifold can escape. If these drains are blocked, it may be discovered that while the engine starts easily most of the time, it struggles to start on occasion. This is due to petrol collecting in the manifold and making the mixture fed to the engine too rich to burn
- 8 The inadvertent use of the choke when the engine is warm may prevent the engine starting. The cure is to turn the engine over the throttle is held wide open. At low engine speeds and a wide throttle opening the carburettor no longer operates and the engine will clear itself of the excess petrol.
- 9 Too rich a mixture will make an engine difficult to start when hot.
- 10 Excessively weak mixture may also give insufficient compression of the fuel mixture to start the engine.
18 July 2022
17 February 2023