I am trying to slow the idle speed on my '95. I have the factory manual but don't or can't figure it out. It says the idle adjust screw is on top of the carb but it appears it is air- fuel adjust only. Where is the speed adjust? I would like to get down to 800-900 RPM like factory specs.
This screw is on the front, not on the side where you find the mixture. Its right beside the solenoid with the wires coming out of it. Its a little hard to see sometimes as its pretty much right under the crossmember that holds the shifter. Look in from the drivers side towards the front of the carb. It actually is more on the front than the top, but comes up a bit. Often hidden under a vacuum line or the wires for the solenoid. I am pointing at the screw. hope this helps.
In the manual there is a label there that says MAS? what is it? Does it stand for Mixture Adjustment Screw?
Mas & Sas KG, First - Welcome. And yes, in my Mits manual it abbreviates the two adjustment screws as: MAS - mixture adjusting screw SAS - idle speed adjusting screw later, slim
Thanks slim... one question i have an F6A carb engine mounted at the rear...everytime i start up my engine, it revs up for about 3 seconds and dies down to idle RPM...i tried adjusting the MAS which is in the middle of the 3 and 2 hoses(right?) - turned it 2 turns up after the engine started stuttering...second i adjusted the one screw right of the MAS(if your facing forward) - what it did was increase idle speed when i turned it so i adjusted it to have the idle speed at normal by listening to the engine... what do you think should i do? i will try to post the pic later if i get my hands on my card reader...thanks
But what is the problem? The high rev then idle down? Its supposed to do that to a certain degree depending on the temperature.
KG, First, I agree with MiniBrutes, I wouldn't be concerned with a slight rev up at start if it settles down to normal idle (as you posted). And if that was the only problem----don't know that messing with your MAS would have done anything to correct that. As for as where your MAS is located on the F6A - couldn't tell you. And for your second question (about what you should do), I would adjust your MAS back to where it shud be (do this at operating temp) and then adj your idle speed to 900 rpm (+- 50rpm) and then drive it. If you can't tell the "sweet spot" on your MAS adjustment drive it a while and then pull/check your plugs. Hope this helps...........later, slim
Does anyone know what the high idle should be? mine truck seems to go to about 2600rpm as soon as the rad fan turns on? BTW: I have a '93 DD51T
High idle has a couple of settings. 1 is the thermal warmup and 2 is the "accessory high idle". Usually the high idle for the accessories should only be a hundred or so RPM higher than idle. Just supposed to keep the engine from chugging or stalling when the a/c, heater fan, rad fan, etc turns on. The thermal warm up high idle should come up to say 1500 ish. The other should not be over 1050 or so. These are just my opinions though and do not have any scientific data to back that up. Its just what works for us. So, then when your fan comes on, its like a turbo boost eh!
When the headlights are on or the rad fan is running, I can drive through the bush at a perfect crawl. I have read through the Carb adjustment diagrams that Don posted in the gallery. Do you know how to adjust the 2 seperate "high idles". I see the screw and cam for high idle, is this the accessory one or the warm up one? I get the therm controlled one and the wax plug, but how is the accessory idle initiated? Thanks, Rob
The accessory idle has a vacuum diaphragm which is controlled by a solenoid usually under the seat. Once the solenoid opens it sends vacuum to the diaphragm which pulls the throttle. I don have my info here in front of me, but just look at the carb while someone turns your headlights on and off. You will see the actuator move. Adjust the linkage it is attached to and all is well. We had a lady call up on a truck that would go wide-open when she turned her heater fan on high. Someone replaced a carb for her but didnt set the 2nd high idle. Probably didnt even know it existed, but she would turn on her fan and start accelerating. We laughed about that one. WOT with the fan. Hehe.
Carb tune Can someone help in tuning 94 suz carry carb. It ran great when I first brought it home. Started run rough after 1st tank of gas. I took of fuel filters and cleaned gas tank bc found water in filters. Changed plugs and air filter. Ran fuel cleaner on alltanks since. Now running rich but need help on adjusting carb and where to set fuel mixture screw and idle. Any help will be greatly appreciated.
