Just bought a 79 fiat spider 2000 and I need a little help

[79spiderparker]

I just got my 79 spider carbed home and I need some help. The exhaust is backfiring a bunch any time I step on the gas. Is this related to the dizzy? Spark plugs? Oil or fuel getting in the exhaust some how? Any advise from Nyone would be much appreciated. I'm really looking forward to getting this baby back on the road! I'm no mechanic, just your regular backyard mechanic, figure it out as you go. Thanks, Chris

[vandor]

Are you sure it is into the exhaust and not the intake? The latter is a lot more common, and usually caused by a lean mixture, which is because of a vacuum leak or worn out carb.

If it is indeed backfiring into the exhaust then you may have a bad valve. First I would do a compression test and even a leakdown test if you have the tools, that will tell you the condition of the inside of the engine.

[So Cal Mark]

Csaba is right, ya gotta determine where the backfire occurs. If it's in the exhaust it could be an ignition issue or an exhaust leak. If it's backfiring on acceleration, could be a failed accelerator pump or ignition misifire

[79spiderparker]

Thank you both. I will work on determining where the issue really is and go from there. I'll keep you posted from here on out guys. I've only been on this site a few days, and I already don't know where I'd be without it. Thanks, Chris

[santafe308]

it could be as simple as a empty cat? and the smog pumps hooked up. if i hook my smog pump up to the head it back fires from my muffler on deceleration because i have no cat pipe straight to high flow muffler. just my 2 cents. i could be way off an have a problem my self?