Vapor Lock (Part 2) - Why Your Motor Refuses to Start

[charlieparker1234]

we learnd in our 1st vid that gasoline can vaprz & it could vaprz very quickly.now driving down the road, ur engine gets hot.that's not a problm. as u drive along, the wtr pump moves the heatd coolnt out to the radiator. we can dissipate the heat. we also have a constant breeze racing thru the engine bay. now imagine what happens when u pull up to the 711 & u turn the engine off. the water pump stops. the radiator has no breeze and no cooling fan to create a breeze.

[charlieparker1234]

the air in the engine may become static. theres no air flow. now the engine goes thru a process called heat soaking. that means that all the heat thats inside the engine begins to migrate. the coolant gets hotter than when ur engine is actually running. the temp of ur engine & ur engine bay gets hottr than in any other time. our stopped car has a carb thats full of volatile gasoline sitting on top of this heat-soaking engine.

[charlieparker1234]

The eng then becmes an oven & gasoline inside the carb begins to boil, turning to vapor. think about the fuel that was in the jet thats turned into bubbles of vapor. it's gone. the float bowl is a boiling cauldron. as bubbles rise, its nearly impossibl for fuel to enter the passageway and into the jet. so while theres technclly fuel inside this carb, its of no use to the eng. vapor--not liq fuel--is what comes out of the jet & mixes w/the air entering the eng.

[charlieparker1234]

vapor is much less dense than liq gasoline so the mix entrng the motor is too lean for the motr to run on. it wont start as long as the fuel is boiling. now while ur standing w/ur hood up trying to figure out whats going on, the eng bay is venting. 10 or 15 min of this will bring the temp of the fuel in the carb back down. the fuel will stop boiling. the jet will fill w/fuel & the car will start again as if nothing ever happend.

[charlieparker1234]

to combat this prblm, the gasoline producers changed the formulations of their gasoline from season to season. this tactic works most of the time. however, if u have a tank thats full of gas thats been formulated for cool weather driving & we suddenly have a few hot days or if ur carb is exposed to more heat than it was expected, vapor lock can happn.