sportroadster Posted August 3, 2018 Share Posted August 3, 2018 Having some problems keeping my 28 master roadster running After I fuel up vacuum tank manually car will run for about 5 mins then dies, interesting thing is that it starts right back up and then run for a minute or 2. What appears to be happening is that there is some vacuum and fuel flow to put some fuel in the upper vacuum chamber but not enough to trip the switch to dump the fuel to the lower chamber. once engine dies vacuum is lost and fuel gets dumped. Took tank apart and mechanism seems to be working fine. Vacuum is good enough to run my windshield wiper and I blew out the fuel line back into the tank (there are some very small particles that come in with the fuel') Car did fine on a 50 mile tour we took and then this started. Any hints on how to resolve this, thanks Link to comment Share on other sites More sharing options...
Leif Holmberg Posted August 3, 2018 Share Posted August 3, 2018 Check the brassfilter and the tube inside the gas tank at the rear.Dirty brass filter or a hole in the tube inside the gas tank? Leif in Sweden. Link to comment Share on other sites More sharing options...
Morgan Wright Posted August 3, 2018 Share Posted August 3, 2018 Sounds like the vacuum valve is not shutting off all the way when the engine is running. If the upper tank is filling but not dumping when the engine is running, there must be a little bit of vacuum when the vacuum line should be shut off. Maybe the vacuum needle is clogged with gunk and doesn't close all the way, the needle at the top of the vacuum tank. Take the needle out and wipe it. Link to comment Share on other sites More sharing options...
sportroadster Posted August 8, 2018 Author Share Posted August 8, 2018 Appreciate the recommendations Took the vacuum tank apart again and verified mechanical and valves operations worked properly, they were In the process the top plate gasket broke so I build a new one and low and behold after reassembly everything now functions properly Did a 10 mile test run and no fuel supply issues so gasket must have been leaking slightly. Still need to fix the contaminates in the fuel tank, anyone have an idea how to remove the tank from a roadster, does not appear like I can drop it down Again thanks for the help. Link to comment Share on other sites More sharing options...
Leif Holmberg Posted August 8, 2018 Share Posted August 8, 2018 Of course you can drop it down,but you probebly need to remove the right side "side apron"? after that removed the 2 staps that hold the tank. If the car are on a "lift" you can probebly remove the tank without removing the side apron if you can turn the tank 180 degrees after removed the 2 straps,and the fuel line .There are 2 different type of tanks on 120-128 models ,1 with the filler tube thru the side apron and one stright up .Be sure to empty the tank at first. Leif in Sweden 1 Link to comment Share on other sites More sharing options...
Morgan Wright Posted August 8, 2018 Share Posted August 8, 2018 If the gasket was leaking you would have less vacuum not a vacuum that sticks on. You must have fixed the valve without knowing it. Link to comment Share on other sites More sharing options...
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