jdk81 wrote:
Check the auto-choke first.
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| 91 Sierra mixture screw? https://auszookers.com/forum/viewtopic.php?f=5&t=38471 |
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| Author: | Tommo88 [ Sun Jan 20, 2013 6:39 pm ] |
| Post subject: | 91 Sierra mixture screw? |
Dose anybody know about carburetor tunning? My zook is running rich and just want to know if someone had a photo of the carb fuel mix screw or idle screw? |
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| Author: | Gwagensteve [ Sun Jan 20, 2013 8:05 pm ] |
| Post subject: | Re: 91 Sierra mixture screw? |
Idle speed can be adjusted - the screw is over near where the throttle cable attaches to the carb. There is an idle CO adjustment, it's a tamperproof screw near the base of the carb on the rocker cover side. There is no broad mixture adjustment, from my experience or from the FSM as far as I am aware. Steve. |
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| Author: | jdk81 [ Sun Jan 20, 2013 8:24 pm ] |
| Post subject: | Re: 91 Sierra mixture screw? |
The tamper proof mixture screw (which can be pried off) is often more trouble than its worth removing. It only affects mixture at idle, and thats it. The main tuning is done by the primary and secondary jets. Odds are you shouldn't need to mess with these either. Until you can do some type of exhaust gas analysis, and read the plugs (if required), fiddling with the jets and mixture screw is way out of most peoples league. What set up do you have? In the FSM there's loads of info on how to love your carby. Check the auto-choke first. Check the float level (these seldom get changed by themselves, more so by people being rough when pulling the carby apart, or "adjusting" the float themselves). etc |
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| Author: | JrZook [ Sun Jan 20, 2013 8:27 pm ] |
| Post subject: | Re: 91 Sierra mixture screw? |
jdk81 wrote: Check the auto-choke first.
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| Author: | Tommo88 [ Mon Jan 21, 2013 1:38 pm ] |
| Post subject: | Re: 91 Sierra mixture screw? |
It would be the standard carby that came out on this car. This car has never been modified of tinkered with just hasnt been tunned in a while i suppose. I would much rather do this all myself all i need is a manual and some tips. I can borrow a timming light from a friend so i can have a look at that also. How does the suto choke work? |
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| Author: | jono165 [ Mon Jan 21, 2013 2:29 pm ] |
| Post subject: | Re: 91 Sierra mixture screw? |
The sierra carb is pretty straight forward. At that age theres probably some gunk in the fuel bowl and through the jets. I rebuilt mine when I got it because the auto choke wasnt functioning properly. You shouldnt need to adjust the idle mixture unless is hasnt been tampered with, off idle all the fuel metering is done through the jets. The auto choke operates on coolant temperature so when the car warms up the wax pellet expands turning off the choke. It is not uncommon for the choke hose to become blocked which means the wax wont heat up resulting in high idle. When first started it should idle around 1500rpm until warm and should then idle at 850rpm i think it is. Theres a sticker under the bonnet usually that has the idle speed, timing, and spark plug specs as well as valve clearances. If you have a rocker cover leak when you change it its a good time to check your valve clearances. Theres a website called acks FAQ which has service manuals on it that you can download. Just be careful the American Samurais had a hitachi carb not the aisin one we got here so any SJ413/Drover/Sierra manual will do. You can probably find a tutorial online of how to rebuild the sierra carb, theres a couple of toyota ones that are also similar. Edit: if you rebuild your carb its also a good idea to run a little inline filter between the fuel pump and the carby. |
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| Author: | Tommo88 [ Mon Jan 21, 2013 3:31 pm ] |
| Post subject: | Re: 91 Sierra mixture screw? |
Thanks heaps mate that has turnend me in the right direction. I'll buy myself a rebuild kit and get started in the next few weeks. Cheers 
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