Carburetor 'Pops' at Low Idle, upon Starting

[Dirtymech]

Hello everyone,

This is regarding the carburetor on a 1984 Honda Accord LX. The carburetor on this vehicle wheezes and pops (i.e. intake is going out the WRONG way) when attempting to start the vehicle AND during low idle, at which it is prone to dying.

Sounds like a timing belt issue, right? Well this whole mess started immediately AFTER a broke timing belt on the vehicle was replaced. I'm trying to solve this issue for the guy who owns the car, and I wanted to check with all you smart folks here at the Automotive forums to see if you could answer this one question for me:

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Is there anything BESIDES an incorrectly placed timing belt that could cause a carburetor to spit intake fumes out the top of the carb?
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I've recommended to this gentleman that I check the timing belt for him, and if it turns out that the timing belt isn't the problem, well it isn't good for either of us. So what do you guys think? Could the valves have been damaged when the timing belt broke, or perhaps the exhaust is partially clogged? Much less likely than the timing, but possible culprits, yes?

[curtis73]

Yes. Its rare that the upper end of an engine isn't damaged severely when a timing belt breaks. The valves stop but the pistons don't. Its possible that no damage was done, but my guess (if you rule out the timing belt) is that some of the valves got smacked and don't seal anymore.

[MagicRat]

Originally Posted by curtis73

Yes. Its rare that the upper end of an engine isn't damaged severely when a timing belt breaks. The valves stop but the pistons don't. Its possible that no damage was done, but my guess (if you rule out the timing belt) is that some of the valves got smacked and don't seal anymore.

I agree. You have bent at least one intake valve just enough that it bleeds hot combustion gases into the intake manifold, which ignites the intake charge and upsets the vacuum signal at the carb, causing the engine to stop running.

Try a leak-downtest to confirm. Chances are a rebuilt head is required.

[curtis73]

If not new pistons and rods...