Rochester B, BC, BV Technical Information Here


Hi Mike, just talked to you on the phone. Did the rebuild, but now I need to choke the carb in order for it to start, no matter how hot the system is. What can I do to fix this. Its a manual choke. 235 1953 pickup. Thanks John

A couple of things come to mind.

Gas boils at a lower point now and I’m hearing a lot of complaints about peculation problems, especially in the hot weather. You get the engine hot, then when you turn the engine off, the gas starts to boil out of the carburetor. A smell of fuel after stopping might be a hint.

Ethanol is one of the bigger problems. Not sure if it will help the low boiling point, but StarTron will help with ethanol problems.

Unfortunately there isn’t a real good solution to the percolation problem. Some have added an electric fuel pump, which will fill the bowl when the key is turned on. Anything you can do to keep the fuel cooler would be a plus.

You may also be having a low fuel problem not attributal to percolation.This would also cause poor operation other than starting the engine.

  • It may be that the float is too low. Adjust to specifications.
  • The fuel pump isn’t putting out enough pressure. Test the pressure.
  • Make sure all of the passages are cleaned out. This must be done by physically running wire down the holes. Ethanol leaves deposits behind that cleaners can’t get out.

From my friend Jeff:

If he didn’t get the accel. pump to work, then it won’t prime . . . although it really should start without touching the gas unless it has sat for several hours without running.  In reality, choking generally tends to make heat soak problems worse, not better — the engine is already flooded, after all.
Could he have a vacuum leak?  Is he running bad gas?  These will also cause a hot carb to need choking.