Hi Scotty
I realy enjoy your videos.
I purchased a 1967 Mustang Fastback S code with 390 engine and 5-speed before xmas 2020. Have not had the chanse of driving it much until now since i live in Norway. It runs very rough after start up, I can barely keep it running and have to pump the gas pedal. Idle setting is around 500 even after adjusted to 750 rpm day before, when the engine was warm. I looked at some carburetor adjusting videos for my Holley and I used a vacum gauge today and the car ran better after warm up. It did not hesitate when accelerating at different gear settings. But I dont understand after 10 min driving the idle rpm went from 750 to a 1000 and when starting cold idle is like 500? I start it by slowly moving the gas pedal down and up once and then it start but rough and slow. Use of the choke seems to worsen the problem and it almost sounds like its going to suffocate. Look forward to hear from you.
best regards, stigo
Any codes?
@Kerem...I don't think he'll be getting any codes. It's a 1967 Mustang.
have we already ruled out the mass airflow sensor (joking.)
It sounds like you need to work on getting your choke adjusted correctly. Your fast idle is not working, which is why it is trying to stall at startup. The engine runs better once warm, which is why the idle speed is increasing. If your choke was working right, the engine would run fast at startup and then slow down as the choke opens.
I don't think he'll be getting any codes. It's a 1967 Mustang.
Millenials, what are you gonna do...
They missed out on the good old days.
That's for sure! Had some fun recently watching a young 20-something relative trying to figure out how to work a record changer.
Anyhow, I'd say your diagnosis is spot on, either his fast idle cam isn't working or the fast idle adjustment screw is way off. For that matter who knows if the choke is properly adjusted. Once that's all working the next mystery to get past will be learning to blip the throttle to disengage the fast idle cam as the engine warms up and idle speed increases. Also wondering if his heat riser is working, those frequently get stuck and can compound carb and choke problems.