Carb backfire

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Jun 26, 2005 | 10:08 PM

fcoppola

Thread Starter

Instructor

Joined: Dec 2001

Posts: 225

Likes: 0

From: League City TX

Carb backfire

I have a carb backfire when I go from idle to WOT. I also notice a 'sucking' sound when I step on the gas an instant before the engine roars. It seems to me some sort of vaccum leak? Today was the first time I had it on the road in 2 years, and at a green light, (NOT WOT) I just went to go and it stalled out and took a few good tries to get restarted.

The car idles all over the place. This happened before these changes and still happens.

new fuel pump
air filter
manifold gasket
valve cover gaskets
ignition cap
ignition rotor
wires / tune up

Note: these were replaced for other problems, but I just thought I'd mention what was replaced already.

I got the car a few years ago and just started working on it. I am sure the carb could use a rebuild. I just want to hear your opinions first.

Jun 26, 2005 | 10:19 PM

greyghost79

Burning Brakes

Joined: Nov 2004

Posts: 1,028

Likes: 0

From: San Antonio Texas

what's your initial timing set at?

Jun 27, 2005 | 01:02 PM

fcoppola

Thread Starter

Instructor

Joined: Dec 2001

Posts: 225

Likes: 0

From: League City TX

I know less than nothing about cars. I bought this hoping to learn on it, but still take it to a mechanic. I could drop it off and ask the guys that did the work mentioned.

Jun 27, 2005 | 02:16 PM

71redskin

Burning Brakes

Joined: Feb 2005

Posts: 977

Likes: 1

From: wash. dc

carb backfire

you didn't mention what yr your c3 is but if you're gonna take it to a shop every time something needs to be done i'm afraid it may be in the shop more than you drive it... part of the joy of owning these cars is being able to wrench on it too... get yourself a aim manual and a shop manual and start doing it yourself...unless of course money is no object for you

Jun 27, 2005 | 02:48 PM

lars

Tech Contributor

Joined: Aug 1999

Posts: 14,370

Likes: 6,364

From: At my Bar drinking and wrenching in Lafayette Colorado

Backfire through the carb is a lean condition. If the car sat for 2 years, your accelerator pump has shriveled up and is no longer functional, causing the lean condition upon acceleration. Replace the accel pump or rebuild the carb.

Jun 27, 2005 | 03:44 PM

rcread

Race Director

Joined: Aug 2004

Posts: 10,628

Likes: 132

From: Duvall, WA

Make sure your spark plug wires are routed properly. This can cause a backfire. And then do what Lars says. Lars just knows things. It's freaky.

Jun 30, 2005 | 10:48 PM

fcoppola

Thread Starter

Instructor

Joined: Dec 2001

Posts: 225

Likes: 0

From: League City TX

Thanks everyone. I have been slowly learning and working. I am actually been tinkering and playing. I just dont want to make things worse. Now that I got it on the road I am going to be working on it more.

What is recommended for a new carb? This one is old and has lots of surface rust anyway. What is a good replacement? I dont need anything too fancy as its the original tired L-48. I have tons more to do before I start upgrading the engine.

Once the carb is done I am thinking of attacking the power steeling control valve. It seems to be a simple replacement. Are rebuilt ones recommended or should I just go new?

This car is going to be a daily driver for the next 2 weeks or so even with the bad carb. Unless I can get a simple direct bolt on replacement with no tuning required. I dont have time to be without it.

I'll be posting most of these as seperate threads, just thought I'd give yall a heads up. Feel free to post to this one or even email me at gadgethead@hotmail.com.

Again Thanks! The good news is I had narrowed it down to a lean condition and/or a bad carb already, so I am learning. Of course I didnt know the specifics. Lars .. You're the man!

Jul 1, 2005 | 03:29 AM

Kalway

Safety Car

Joined: Dec 2004

Posts: 4,071

Likes: 0

From: San Diego CA

What year? A recently rebuilt or a fairly new edelbrock q-jet can run anywhere from $150 to $400. I paid ~$200 for my edelbrock 1904 (electric choke q-jet) it's slightly used (had about a 2 weeks worth of use). New ones generally go for about $300 or more on ebay. The divorced choke ones go for a bit less.