View Full Version : carb problem

12-14-2009, 07:00 AM
I have a 55 Champ that runs smoothly one time then suddenly starts running rough and soon stalls out. If I pump the gas pedal while its running rough it won`t stall .It starts and runs good but will soon run rough and stall again.Spark is good so its not electrical . Any ideas ?

12-14-2009, 09:57 AM
You're not giving us very much information to go on, but it sounds like a float problem. There could be dirt in the needle and seat assembly, such that the float, even at the top, cannot stop the inrush of excess fuel, or maybe the float is punctured, and no longer floats.

A carb with either problem will permit the car to start and run, but once it warms up up, it will quickly flood and die. When an engine quits because of too MUCH fuel, it usually "lopes" or surges rhythmically a few times, as it quits, and emits a lot of black smoke from the tailpipe. If an engine quits because of too LITTLE fuel, it generally just slows to a stop, and you may hear a gasping sound from the carb, if the air cleaner is off.

Sounds like a rich stall to me, since stepping on the throttle and admitting more air gets it going again. If it were a lean stall, that wouldn't happen, unless it were only a plugged idle jet.

If I had to guess, I'd say dirt in the needle and seat.

Gord Richmond, within Weasel range of the Alberta Badlands

12-14-2009, 09:58 AM
Possibly rust/dirt in the fuel tank and it found its way into the carburetor.

Lark ala mode
In the middle of Minnesota

12-14-2009, 10:13 AM
Sounds like a cracked fuel line to me. At low rpm, teh pump can't overcome the loss of suction, so it starts to run out of gas in the bowl, but when you pump it, the extra gas keeps it running in spite of the main jets not feeding, giving it a chance to increase pump flow before the bowl runs so low that the acc pump stops working.

12-14-2009, 10:15 AM
Oh, and hey, welcome to the forum.

12-14-2009, 09:43 PM
Thank you . I will follow up on all these suggestions .

12-15-2009, 04:55 AM
Check for a vacuum leak on carb. Could have loose carb or carb section.

Joe Nichols
12-15-2009, 08:53 AM
Does it run good when the engine is 1st started and cold, then run rough after warm up? If so, you may have an air leak that the closed choke compensates for until the engine warms up and suddenly you have too much air. If you want to test for this problem, temporarily tie your choke in the cold engine position and see if it continues to run smooth.