Small engine vapor lock12/5/2023 This happens on the "suction" or low pressure side of the system (pump) and with any increase in altitude. Any reduction of pressure will lower the boiling point. "Vapor lock" is typically liquid fuel turning to vapor (boiling). The car was restored to stock and I don't want any excess hoses, pressure regulators or gauges under the hood. In an effort to keep the bypass as discreet as possible is why I'd do it just around the pump. The pump will outflow that small oriface by a longshot to feed the Autolite 2100 carb. This would allow any excess pressure to feed back into the open fuel line when an over pressure results from heat soak. This would feed into the line right before the pump. From this tee would be a very small restrictor, maybe. One of my thoughts on fixing this was to Tee into the line just above the pump. My belief on this is the fuel in the line between the pump and carb heat soaks and is putting enough pressure to blow the needle off the seat. Perhaps dropping to a 180 might make the difference. After driving on the highway then stopping and shutting off the engine it will heat soak and you can see the fuel boiling right out of the boosters in the carb. Optimally, the best course of action would be to put a fuel pressure regulator right before the carb that has a return line to the tank.Īnother problem I have is with my 69 Cougar 351w 2v. I would guess the clogging filter which was near the carb would slow down the fuel flow allowing it more time to warm up in the pump and line to the carb. There must have been quite a bit of sediment in the tank of that truck as I went through more fuel filters in that truck any other vehicle.still do. One of the things that would help the situation was to change the fuel filter. Usually it would refill before I had to pull over. Sometimes it got so bad, when I'd stop for a toll booth on the highway, then take back off at a moderate speed it would die out. And remember fire saftey, have an extinguisher etc ready because you will be allowing fuel to escape doing this, you do not want a fire.I have a 78 F-150 with a 460. Do it while someone cycles the key, but not cranking the engine. If you have a 525EFI, 502 Mag EFI, or similar motor with a single dead head rail you can take a rag, and small screw driver and just bump the tip of the schrader valve on the end of the rail and all the vapor will burst out. On carbs you can use an electric fuel pump to fix vapor lock only because once the float bowls have vaporized the needle and seat opens (or you have supplied enough pressure to overcome the needle and seat) and will bleed themselves when fuel flow is supplied to them, EFI will not do the same thing, the injectors open for such a short amount of time and have such small outlets they will not bleed air very effectively. your only sure bet is to bleed the vapor out of the rail, usually through the schraeder valve on the end of the rail. If you have a dead head rail system no amount of fuel pumps/booster pumps will solve the issue, once the fuel has vaporized you can't put enough pressure to it to re-condense it. Most custom builders will run a flow through rail, where fuel is continually being circulated through the fuel rail and back to either a vapor seperation tank, or to the main fuel tank. OEM builders make their engines this way 1) cheaper than having a flow through and less complicated to install because there is no return line to the main fuel tank, and 2) warming of the fuel by flowing it through the rail adds slightly to it's evap rate, and this is a huge EPA hurdle in the name of emmisions testing. Vapor lock today is a symptom of a dead headed fuel rail combined with low boiling point shitty ethanol fuel.
0 Comments
Leave a Reply.AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |