Can anyone confirm on an 85 hijet the valve looking filters on the vacuum lines on the carburetor are check valves? Parts 55 and 95 on the vacuum line diagrams for s83 Should these allow air through if you blow on them? Neither of the two... the one between the choke, or the one between the heavy load idle control would allow air through when I tried blowing through them.
vacuum leaks are 85% of carb and idling problems, use a vacuum gauge or carb cleaner, carb cleaner will send the engine to high idle if you have a vacuum leak, make sure the vacuum port in the air cleaner canister is working properly, also check that your vacuum advance hose isn’t cracked coming off the distributor to the vacuum manifold tree. The vacuum manifold tree is brass on the bottom to go in to the block and plastic on top. Plastic wears out with time and will break or leak, which causes a vacuum leak. Some manifold vacuum trees are 3 or 4 port, make sure to replace it with a new one. When I buy parts I buy 3 at a time that way I have them on hand or in case they can’t get them any more. The vacuum manifold tree is located behind the carb. If you looking at the carb from the right side of the bed, it will be to your 1 O’clock tucked down inside. Remember to use a marker or different colored tape to mark the vacuum lines so you know where everything goes back too! Good luck!’
I have this exact same question, any new insights? I can not blow through either of those check valves in either direction. They are black body with green nipple on one end and clear opaque on the other. I installed a new thermostatic vacuum switch since my was broken. And I discovered a couple missing vacuum lines. I just need to know if these vacuum check valves are bad. And if so has anyone seen any available anywhere. I can’t find them anywhere.
