| Show 1 e r HO 1 I to in t n n r r re re reDY BY DY ISRAEL EL KLEIN Science Scle-nce Editor XEA NEA Service car is running I along THE smoothly and picks up quick quick- quickly ly when there I la Ls a sudden series of backfires Its It's especially when the engine Is I speeded up or the car Is climbing a hill hlll with the accelerator ac ac- accelerator accelerator down don to the tho floor board that this backfiring occurs occur What's the trouble 1 The fuel ruel system cistern most likely is b 1 clogged The line from the main tank to the vacuum tank may have some lome dirt or sediment In Int Jt t. t enough to top stop the stop the flow to the tank The strainer at the tho th top of the vacuum vacuum acu lm tank may mo be holding up the th low How of fuel tuel The carburetor may mayy In be clogged with dirt The way to find the seat of ot such euch obstruction is la to work back back- backward backward backward ward front from carburetor to main tank First tho the carburetor If It the carburetor leaks lealS badly the tho float needle valve doesn't scat seat proper proper- properly ly due to sediment under It The needle valve should be turned a afeW afew feW lew times to clear this sediment If It the carburetor Is dry however how how- however howver ever ver the trouble Is in the system Ahead of ot It Next the vacuum tank Some Some- Sometimes Sometimes Sometimes times fuel is drawn direct from this tank to the Inlet manifold due to a a. leaky valve in the tho tank This can be bo ascertained by re releasing re- re releasing leasing the connection to the man man- manifold manHold manifold Hold and noticing whether any fuel tuel Is dripping from It This line should be dry for It Is used as a suction line to the vacuum tank To test the vacuum tank re remove rev re- remove move the tho lug at the top and pour In a tI small amount of gas Start the engine and rust ruB with the throttle closed as near as possible to idling when suction Is b great great- est While the engine Is running put Jut your finger at the plug open open- opening openIng opening ing and feel teel If It there Is any suc suc- tion If It oo so the tho vacuum tank is working properly and the trou trou- trouble trouble I ble is somewhere re ahead of ot this Of Ot course there must be bo gas in inthe Inthe the main tank If It so the vent ent ventIn ventin entIn In the cap must be open If 11 that's the case the trouble most likely lies In the lino line between the main tank and the vacuum tank Probably Probably I ably a a. chunk of ot dirt lodged in a aI I curve stopping the flow of ot gas gu I To clear this release the line at atthe atthe atthe the top of the vacuum tank at attach at- at attach attach tach the hose hoso of ot a tI tire pump and I pump air through It a few rew times This well force toree any obstruction back baek into the main tank and open the fuel tuel system To avoid recurrence of ot the trouble the main tank should be drained and cleared of sediment |