Desperately looking for help with my vespa ET4 . I've got an et4 that simply fails to start . It's got a good spark , the fuel pump seems to be working , i,ve taken the fuel pipe off the tank , tried starting and it pumps fuel , however , it doesn't seem to be getting fuel into the cylinder . Is there a fuel cut off on the carb ? yesterday it wouldn't start at all ,so this morning i took the pump out of the tank , blew it out , replaced it and it started , went to restart it half an hour later and it just will not start . I've worked on hundreds of older vespas and know my way around 2 stroke engines with my eyes shut but this thing is really baffling me . Thanks in advance , Doug
The fuel "pump" is a vacuum petcock. The vacuum from the engine opens the valve and lets fuel flow. Test it by pulling the vacuum line from the intake and the fuel line from the carb. Suck or apply pressure to the vacuum line and fuel should flow. If not then bad hoses or petcock.
I seem to remember when I had one that the fuel system was very temperamental and was very fussy with regard where the fuel line should run. if I remember right it had to run lower than the inlet into the carb and then upwards into the carb sort of like a waste pipe in a sink. and of course very important that its getting sucked with a good vacuum from engine. why these couldn't have been electric pumps Ill never know.
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