[lyndon123]

Hi guys, im very new to sierras and have just picked up my first one..

since i have had it its been idling high, i beleve its because the previous owner has advanced the timing, as i set it back to std and it was idling fine, but that stopped me from getting upto 100kph witch is dangerous cause i live on a highway, i was just wondering how to bring my idol back down to less than 1800rpm and when i turn lights on its well over 2300rpm and its very annoying

thanks in advance

[Ben_Sierra]

There is an idle adjustment screw on the side of the carb. Someone here will have a pic...

But a high idle iteslf wouldn't prevent you from reaching 100kph, so something else is not quite right either...

We'll need more info to diagnose...

[royce]

pull the top air intake thingo off your carb and first check the choke is fully turning off when its up to temp

the idle screw is accesed from teh passengers side rear of the carb, its part of the throttle linkage

for the high idle when lights are on, get somebody to turn the lights on and watch the front of the carb you will see a vacuum actuator move, its adjustment screw sets the high idle

[SJ70MOZ]

what should it idle at with the lights on?

[royce]

they have a setup to up the idle speed with high electrical loads, which is lights and heater fan, stop the battery going flat

[foolsp33d]

this can also be checked by unplugging the electrical plug on the front of the carb. and listening for the click IIRC..idle up we are talking here... you could also turn your headlights on and disonnect the vacume line to the idle up thingamabob..

It would also be worth checkingwhere your accelerator bolts into the cab. I noticed driving today mine has deeloped a bit of a loose bolt syndrom and its causing the pedal to not return .. i physically have to lift it with my foot between gear changes and when slowing down.. is a RIGHT PITA!

[SJ70MOZ]

royce wrote:

they have a setup to up the idle speed with high electrical loads, which is lights and heater fan, stop the battery going flat

yea i understand what the stepup solenoid is for but i don't know what rpm the motor should run at when its under electrical load. Turn my lights on and it bumps it up to 2grand!

[Rhino]

SJ70MOZ wrote:

what should it idle at with the lights on?

Mine rises by close to 500rpm for lights then same again if i switch the fan on.

[jdk81]

idle at 850 rpm.
high idle around 1300 rpm or so is fine, check the manual
EDIT: manual is in download section

Manual says 1000 rpm.
Mine idles higher when I turn the parkers on because there is almost no load, once the headlights are on the rpm drops down as the alt is supplying the power for the lights (2 x 130/90W).

[SJ70MOZ]

yea that makes sense. Thanks for the advice guys and sorry to lyndon123 for hijacking ur thread

[royce]

SJ70MOZ wrote:

royce wrote:

they have a setup to up the idle speed with high electrical loads, which is lights and heater fan, stop the battery going flat

yea i understand what the stepup solenoid is for but i don't know what rpm the motor should run at when its under electrical load. Turn my lights on and it bumps it up to 2grand!

ha lol sorry teach me for not reading properly

I unplugged mine, unless you are up around 2 grand its not really helping

[Che]

Is there another way to adjust idle?

I recently replaced my accelerator cable and it was about 1/2 cm shorter than the one it replaced. Idle speed screw is wound out as far as it'll effectively go, so too the new accel cable (where the thread/bolts fix onto the carby attachment) - it can't be lengthened any more without falling off the thread.


Idle speed is still 1300 RPM and I can't drop it anymore.

[Ben_Sierra]

Get the right length cable....

There should be a small amount of freeplay in the cable at idle...

If there isn't and the cable is wound right out, aint nothing gonna fix it...

[SJ70MOZ]

royce wrote:

ha lol sorry teach me for not reading properly

I unplugged mine, unless you are up around 2 grand its not really helping

so having not plugged in hasn't caused any problems? Or have u up graded ur alt?

Its only going to make a difference at idle isn't it, so if ur not idling for long periods the charge rate shouldn't really be affected. Am i on the right track?

[Ben_Sierra]

Yes, it only makes a difference at idle.

All the time your driving around it will be fine.