Auto Racing: no subject, spark plug wires, gasket rubber

Question
hello there i think ur 1 of the greatest technician on these questions... (1) i have a carborated car and when it is throttling it is going high and low. like it goes up for 1 second and drops the other second and it continues like that but when i keep a steady rev on it, it revs steady, what is the problem with it and how can this be corrcted

Answer
hi richard

this could be one of two:

1- electrical problem where you have a spark leak somewhere on the spark plug wires, turn on the engine at night with the hood open and watch the cables when you rev the engine up... if their is a leak you will be able to spot the sparks jumping from the cables to the nearest earthing available... if so then replace your cables. BTW how old are your spark plugs?

2- mixture problems where you might have a vacuum leak somewhere so your engine is sucking more air than it should so it messes up your mixture, diagnosing that is hard as you have to listen carefully to the engine during idling to hear any "sucktion" sounds... depending on your car it could be an intake gasket, rubber junction or an untight bolt on the piping somewhere.

also check the carburator itself... it could be dirty or so and nor delevring the correct amount of fuel at mid range revs and causing the hesitation.

MMamdouh