Need help with weber carb

[MitMon88]

I Put a 32/36 Weber with a electric choke on my montero. It works fine when its warmed up and on the road, but its hard to get driving because the carburetor doesn't want to idle in the cold. I've adjusted the idle speed to 1 1/2 turns, and not over like it says in the paper work. And the choke plates are closed when cold. Looked for vacuum leaks around the intake and tested for vacuum and both were good. The screw behind the choke doesn't step down the rpm like it should, kinda feel like it doesn't work even though I made sure its touching the cam step down thing. Not sure what it is:confused:, any help is appreciated, thanks for reading.

[SubGothius]

With the main idle screw turned in 1-1/2 turns, did you also verify the idle mixture screw is turned out 2 full turns from fully-seated (just snug, not tight), then fine-tune that with the engine fully warmed up? You'd just turn it in 1/4 or even 1/8 turn at a time until the engine starts noticeably stumbling, then back it off to the last adjustment point you were at before it started doing that. If the mixture screw winds up more than 2-1/4 turns out or less than 1-1/2 turns in, your primary idle jet needs to be larger or smaller respectively.

The screw behind the choke element steps UP the RPM above base idle when the choke is closed, which engages the fast-idle cam against that screw. Try this with the engine off and fully cold:

Open the main throttle slightly, press the choke plates closed, then release the throttle. This should set the choke fast-idle cam against the adjustment screw for that. Turn that screw all the way in (just snug, not tight); you can ease it back out later once you're sure you've got basic cold-start functionality working. Loosen the ring holding the choke element and fiddle with turning the element housing either direction until you're sure the spring inside is at rest, not applying any tension either way. Gently turn the element counter-clockwise until it just barely starts to apply tension, then tighten the retaining ring. Make a mark or scratch across the edge of the element housing to the linkage housing behind it, as a reference point for this adjustment.

Press the gas pedal twice to squirt some fuel into the carb, make sure the choke plates and fast-idle cam are still engaged as described above, then try starting the engine. DO NOT touch the gas pedal while cranking or during the first 10 seconds or so of warm-up. If it starts, let it warm up for at least 10 secs. or so and then blip the throttle to release the fastest idle step on the cam (there's another step or two until the choke opens fully). Let it warm up to full, regular operating temp, then check the position of the choke plates, which should now be wide open. If they're not open, loosen the retaining ring again and rotate the element housing gently clockwise until the plates are just barely all the way open, then tighten the retaining ring agin.

Find the mark/scratch you made earlier, which will now be misaligned, and make another mark to complete the "missing half" of either original mark. This along with the original mark will indicate your most likely range of adjustment to fine-tune the timing of choke opening if needed.

If the engine did NOT start with the choke closed as described above, your primary idle jet is probably too lean; try going up a size.

[geezer101]

Biggest question will be - is it a genuine Weber? You won't be the last one to get burnt by the knock off carbs from China and they can't be tuned to run due to the way the metering galleries are designed. If you know it's legit, follow the advice SubG has posted up for you. Good luck :thumbup:

[MitMon88]

Thanks for your help! Great information, I'll go out and try your suggestions.

[MitMon88]

Bought it from Pierce Manifolds and it has markings that appear to be authentic, such as made in spain.

[MitMon88]

"Open the main throttle slightly, press the choke plates closed, then release the throttle. This should set the choke fast-idle cam against the adjustment screw for that." "DO NOT touch the gas pedal while cranking or during the first 10 seconds or so of warm-up. If it starts, let it warm up for at least 10 secs."- This was a major help in resetting the fast idle cam. Also knowing not to use the gas pedal when cranking made a world of difference. Thanks again for the advise, runs like a champ!

[SubGothius]

Bought it from Pierce Manifolds and it has markings that appear to be authentic, such as made in spain.

Yes, if it's got the Weber name/logo and "Made in Spain" cast directly into the carb body/top cover, not just an ink stamp or decal, that confirms it's the genuine article. Glad my tips helped you sort it out! :thumbup:

And just to clarify/confirm, you shouldn't need to engage the choke/fast-idle cam manually like that once you've got everything adjusted properly. Just press the gas once before cranking to engage the choke and fast-idle, maybe press it once again (or maybe twice if it's REALLY cold) to squirt some more fuel in, then crank away, let it warm up for 10 secs., blip the gas to settle the idle, and drive off.

[MitMon88]

Thanks for clearing that up, works great. Starts up in a snap!