Hello,

My 1972 Plymouth Duster has a 225 cubic inch slant 6 and It's having trouble idling. The engine will run fine except when its going slower than 15 miles an hour on the road or when it comes to a stop. At this point, I have to throw it in neutral and keep hitting the gas pedal so that it doesn't quit running. I know there's a small vacuum leak somewhere that makes a load whistle sometimes but Its never caused this type of problem until now. Could this be the cause of a major vacuum leak? perhaps the carburetor is just getting to old?

Thanks,

 

Could also be a bad hose ????
Or a vacuum plug fell off???

 

The vacuum leak would be the first thing to repair. You may have more than one leak now.

 

DD -

Vacuum leak (big or small), or fuel metering problem (carb).

Archer

 

The engine has a small one barrel carburetor with 3 hoses of which I have replaced two of them. I don't see anything wrong with the 3rd hose with the naked eye. How do I go about testing to see if there is a vacuum leak somewhere?

 

Don't forget to check for a leaking power brake vacuum hose or the brake booster itself. You can check for other leaks around the carb base or intake mounting by carefully spraying ether around them. The RPM will change if there is a leak. I have heard WD40 will work too.

 

DD -

Spray the running engine. including gasket areas and both ends of vacuum lines with a soapy water solution and listen for a change in rpm/sound.

Archer