[newzuki]

Noob question.
Just go my 1992 Sierra project blue slipped and registered. All good. Very pleased with drive ability and new suspension etc.
But one small query. When decelerating in 3rd and 2nd can sometimes backfire in exhaust.
It’s timed well at 850rpm and 8 degrees off flywheel.
Does smell a little “fuelly” in exhaust. Could the carb being running a bit rich. Is so is there a mixture screw on the carb that can be adjusted leaner.
Thanks,
Matt

[Jack jr]

G'day I would check if the exhaust has a leaking gasket or a hole.
Cheers Jack jr

[newzuki]

Thanks
After further searching on the forum have realised that there is a blocked off mixture screw that is better off left alone.
Some suggestions about checking vacumn lines?
If air is getting into exhaust that would give enough O2 to allow combustion?
Thanks

[alien]

Are you still running the factory wax / auto choke?? If so, odds are it's failing/failed =)

[newzuki]

Yes I assume so. Can it be removed?

[Gwagensteve]

I'll fix it for you:

alien wrote:

Are you still running the factory wax / auto choke?? If so, odds are it requires adjustment =)

I can't stand the idea that people pull things off of carbs and therefore put up with progressively less functionality and more compromise because they failed to bother to find out how it works.

As much as I couldn't care less about carbs, they're not as complex as people think and they're not a magical box of hocus pocus.

Get a factory service manual, set the carb adjustments up as described and then, if something doesn't work follow the troubleshooting guide to fix it.

there's a perception that every carb needs "rebuilding" and this is false.

Generally, the idle jet gets blocked with debris from a failing fuel pump, and other than that, ignorant mechanics and owners have been in there "tuning" them by fiddling with every external adjustment, when, basically, they can't be tuned because there's no need, they just need to be setup as the factory intended.

[alien]

But those wax chokes do fail and get stuck running rich.