In Reply to: fuel pump pressure? posted by jonz on September 06, 1999 at 22:20:04:
I've noticed the half full fuel filter on my car. It runs fine none the less. The down draft webers are designed run on pretty low fuel pressure, on the order of 2.5PSI. If you don't have a way to measure the fuel pressure going into the carb I would take Ben's approach. If things are getting "cruded up" you WILL see crud in the fuel filter, fuel pump filter ( my pump has one, I'm not sure if all of them do), and especially in the tiny and tightly knit filter at the input of the carb. The carb filter is exposed by turning that 17mm? nut that lies below the fuel input nozzel and is the first place I look since it is so easy to examine.
I'm guessing binding throttle linkage, worn throttle shafts, or some other air leak. Make sure that both butterflies are closing all the way down all the time. Make sure that all of the spring are there.
I still haven't been able to spray anything into my throttle shafts and cause idle fluctuations, but if I pump the throttle 20 or 30 times with the car off I get I slight gas leak out of the rear primary shaft. This is the only test I know of to check for worn throttle shafts aside from taking them apart ( not for the faint of heart).