View Full Version : idle issues

07-08-2008, 03:07 PM
Hey MC Fans-
First time logger, long time reader- have 91 prostar 190 w/351 ford- the engine runs fine above 2000 rpms. At idle or anything under 2000 rpms it dies out. Replaced spark plugs this spring ran fine for a month. Thought maybe bad gas-added system cleaner- no help. Any ideas?

07-08-2008, 03:15 PM
Fuel system cleaner isn't servicing the fuel system, just the fuel. You should have at least one filter and these don't last forever. How clean is your flame arrestor?

07-08-2008, 04:41 PM
Have not checked flame arrestor. Plan to do so now. I was also going to check PCV valve, carb fuel screen and fuel filter?

07-08-2008, 04:55 PM
Might as well do it all. There's also a screen on the fuel pickup tube that's under the aluminum fitting the fuel line attaches to. remove the fuel line and the fitting unscrews. The fuel line barb is threaded into an anti-siphon valve and this can clog, too, so you'll want to check that as well.

07-08-2008, 05:00 PM
I will try that. Thanks for the help!

07-08-2008, 07:22 PM
Your problem is totally symptomatic of a vacuum leak or a clogged idle circuit in the carb, OR a stuck float/needle/seat, causing it to flood at low consumption modes. Does it emmit black smoke when the symptom is present?

It can't be a restricted fuel filter, screen, or flame arrestor if it runs fine ABOVE 2K RPM (though that doesn't mean that those items aren't over due for service).

To fix the immediate problem, identify if it is smoking (black) when the symptom is present. If not, check for vacuum leaks. If none are found, you'll need to remove the primary side metering block from the carburetor and give it a thorough cleaning.