Help with my coughing, backfiring Comet

[Anonymous]

Hello. My '64 200ci recently developed a problem. I can start it, but it won't accelerate. It just coughs and backfires and bogs down. Here's what I've done/verified so far:

-Initially, I suspected fuel pump, but it's working.
-Next, when it wouldn't start at all, I tried starting fluid. It fired and ran great until the starting fluid ran out. So I suspected the carb. I've switched carbs. Now it starts and runs, but it won't accelerate.
-Coil works.
-Plugs are new.
-Plug wires are set for proper firing order.
-I have advanced the timing and retarded it. Doesn't help.

Could it be the distributor?

Also, I have a Pertronix unit, which has been in use for about 5 years with no problems. Could that be it?

Any help appreciated.

 

[mustang6]

Accelerator pump in the carb gone bad? The diaphrams in these often dry out and crack in a carb that's sat on a shelf for awhile after having been used. Symptoms are exactly as you describe.

With the engine turned off, pull on the throttle level while looking down the throat of the carb. You should see a good, healthy squirt of gas go into the engine. If not, the pump is shot and the carb needs rebuild.

 

[MustangSix]

I'd do a check of the ignition system. Sound like a misfire condition caused by lack of spark, poor spark, or some other failure.

Do you have a set of points you can swap back in as a check? You don't need to tune it too closely, just get it running to see if the condition persists.

How do you really know the coil is good? You could have spark at idle, but not enough to rev. It would be hard to tell without an oscilloscope. If you have another one handy, give it a shot. Or if you don't spend the $15 to get a new one. Coils can grow weak with age too.

Is the inside of the cap dry? Moisture can cause crossfire problems and poor acceleration.

Don't start tinkering with the carb until you have positively ruled out everything in the ignition.

 

[Anonymous]

Don't start tinkering with the carb until you have positively ruled out everything in the ignition.

True.
But it sounds like carb problems.

 

[69.5Mav]

Andy in Indy

Check the fuel filter. I've seen them get plugged enough so that they will bairly idle and wont flow enough for accelleration or normal operation. Rust builds up in the gas tank then gets caried by the fuel to the filter where it eventually stops the flow of fuel starving the engine. It will appear as a reddish powder. I have a 73 maverick the would plug every 100 miles. I used to carry tools and a supply of fuel filters and when the car would start to starve I would change the fuel filter and continue driving. I recycled the plugged fuel filter by allowing it to dry out then I blew it out with compressed air. I no longer have this problem because I remove the tank, cleaned and sealed it and reinstalled it.

Good Luck
69.5mav

 

[mutt]

from the Brit motorcycle world: 90% of all carb problems are electrical.....mutt

 

[Anonymous]

My experience is that backfiring through the carb is caused by 1 of two things.
1) Retarded or insufficient ignition advance.
2) Vacuum leaks.
Doug

 

[Anonymous]

from the Brit motorcycle world: 90% of all carb problems are electrical.....mutt

another tid bit from the Brit bike world

Funny how rebuilding a carb and tweaking points might even get you home but still won't fix a bad condenser.