Proud owner of a '66 MGB. Problem is that when the car is warm it doesn’t want to start. I have new plugs, rebuilt carb., don’t use the chock when the car is warm and never touch the gas peddle (or even think the word gas). It starts on a push but I’d like to fix the problem and make driving the car a little more reliable. Love your show…never had the nerve to call in. what can I do to help keep you on the air.
TKS
Dave Hughes, Newport Coast, CA
Model and make of car is not available on your dropdown list below. ergo it’s a 1966 MGB
Why are you so adamant about not touching the gas peddle. Step on the gas and start it. Pumping the accelerator will not flood an SU carburetor and it needs the throttles open to let it draw enough air to start.
Oops. My bad. I have a Healy carb. Not the traditional SU system. I’ve tried both pumping the gas and opening the chock…to no avail. Thanks for such a prompt reply.
Dave
Did it used to run OK, but now does this, or has it always done this?
Bought the car four yrs ago and it would start hard when cold and hot. Had the carb. rebuilt and a good tune up and that seems to have resolved the cold start problems (I do have to use the chock with NO gas to start it even when cold - but it does start. I live in So. Calif; when it is hot outside I noticed that the car starts hard (when warm). Could this be a fuel pump problem or a leak in the line leading to the carb. If i give it gas after it warms up I notice a gas odor… It does start sometimes without problems but sometimes it gets a little iffy. Thanks
You say it’s a Healy Carb(singular). I might guess that it’s a Zenith Stromberg carburetor from a later model British car but those had automatic ‘chokes’ and so I am even more curious as to what you are dealing with. Could you have a Weber side draft? Or even possibly a Weber-Holley 2bbl downdraft? Regardless, though, if the fuel line is too close to the exhaust manifold due to custom fitting a carburetor vapor lock is a likely cause of the problem.
Oh Yeah… Next time you stop and expect to have the problem open the bonnet and leave it gaping while the car sits. If it starts when you return consider vapor lock the problem.
will do. what do i need to do to correct vapor lock? why were you there so late last night. Do you have a swing shift on staff or just not go home at night?
thanks
Dave Hughes
Vapor lock occurs (almost entirely on cars with carbs rarely to cars with fuel injection) when the gasoline heats up and boils, preventing the liquid gas from moving as it should through the carb. To prevent it requires isolating the fuel system as much as possible from heat, such as moving the fuel line away from hot areas (like the exhaust manifold mentioned by RK). I’ve also insulated lines using closed-cell foam tubing that is used in AC installations. But first thing is to make sure the fuel system is working correctly, especially the choke.
You may have fuel leaking into the manifold. Try holding the gas pedal to the floor while trying to start the engine when it is hot to see if that helps. If there is a buildup of fuel that proceedure should help clear out the fuel. Also, do you have a problem restarting it right after you shut it off? If that is ok then it is another sign the fuel may be leaking into the manifold.
As a side note- The replies you see here are open to anyone on line who cares to reply to your thread. Tom and Ray very seldom answer any questions here, along with any of the CarTalk staff. There are a lot of regular members here though that are very helpful and usually solve problems quickly for folks needing help.
Thanks then to the mystery member. I will follow your advice and see if that helps/ It’s another very hot and sunny day in Southern California so maybe I can put your advice to the test. thanks again
Dave Hughes
Drop us a line with the results, Dave. Good luck.
Does heat affect cranking speed at all?