![]() ![]() I haven't heard the crackling with my carb but I figured that's what happened since it seems to empty its self when I shut it off. That was with the original carb spacer that had coolant running through it. I'm used to it in fact! But I did try a borrowed carb one time and when I shut the car off that thing sounded like a deep fryer crackling away. What symptoms lead you to believe fuel is boiling?I could be wrong about the boiling, I've sure been wrong before. Adding the return style fuel pressure regulator solved the problem.ġ969 R Code Mach 1, Drag Week 2005 Winner BB/NA with 511" FE(10.60s 129), Drag Week 2007 Runner Up BB/PA with 490" Supercharged FE (9.35 151)ġ964 Ford Galaxie, Drag Week 2009 Winner Modified NA with 585" SOHC (9.50s 143)ġ968 Shelby GT 500 Convertible, 492" 667 HP FEĢ005 Ford GT, 2006 Drag Week Winner, 12.0 Daily Driver The advantage here is that the fuel is constantly circulating through the fuel lines this keeps it cool, rather than allowing it to heat up while sitting in the fuel line in the engine compartment while the carb is using very little fuel. This is a fairly major modification, requiring a return line going from the regulator back to the tank, in addition to the normal line from the tank to the fuel pump. Eventually I went to a return style fuel system. It helped, but did not completely cure the problem. This kept the fuel line away from as much engine heat as possible. First I repositioned the fuel line so that it ran from the fuel pump, out towards the fenderwell, up the fenderwell and then across the engine compartment to the carb inlet. I was able to solve the problem using a two pronged approach. So, modern gas + carbuetor and high underhood temperatures can lead to fuel boiling issues. ![]() It kinds of makes sense that when you think about it modern vehicles don't have carbs, and they run EFI systems where the fuel is kept under pressure right up to the point of injection, and the pressure is around 40 psi in most cases. Apparently, with modern gasoline, and especially with ethanol blends, the boiling point of the fuel is much lower than it was back in the day. I thought it was vapor lock for a while, but one day I duplicated the conditions with the car in the driveway, and after the hot restart watched the carb, and about 20 seconds after the restart all kinds of fuel started bubbling up out of the primary side vent and flooding the engine, killing it.īy the way, an IR thermometer on the float bowls of the carb showed a temperature of about 180 degrees at the carb. Typically what would happen to me is I'd stop for gas, then start the car and drive off, go about 100 yards, and the car would quit. As soon as it entered the float bowl, it was back at atmospheric pressure and would boil, spitting out of the vent and into the engine. However, the fuel was under pressure up to the carb, so it would not boil until it hit the carb. What happened on my car was after the car was warmed up, then shut off for a while, the fuel in the fuel line would exceed the boiling point. ![]()
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