I have a 46 merc with sbF 302. When cold it starts and runs fine with fuel filter on carb side full. When the motor heats up the filter starts emptying out and motor dies. I have a new electronic fuel pump(Holley blue), rebuilt Holley carb, new coil, wires, and plugs. Brand new tank as well. Any help would be appreciated. Also has anyone ever ran a return line for the fuel system to circulate?
don't know about the lock... but to recirculate the fuel stirs the gas in the tank... helps keep today's gas from gelling... buddy / mechanic will not run a carb on any of the rods he builds... runs injection so it stirs the tank...
Fuel line getting too hot more than likely, need to shield the supply line and a phenolic carb spacer. Nice 46 and 41 in the pic! Sent from my iPhone using H.A.M.B.
What about the gas tank breather (vent) line, it could be clogged or collapsed causing a vapour lock? It needs to be open to allow in air to displace the gas being used by the engine. Just a thought.
Is the fuel also being routed thru a mechanical fuel pump? Where is the electric fuel pump located, and is it mounted above the fuel level in the tank?
Well that eliminates a couple of potential issues. I'd say the next step would be to run the engine till it warms up and stalls. Then disconnect the fuel line at the carb, route the line into another container and turn the pump on and see what kind of output it has. And as already mentioned, make sure the tank is properly vented. Or loosen the filler cap and see if that allows more fuel flow. Is there a filter anywhere inline between the pump and the carb?
It should be fairly easy to add a return line to the tank.. you can drill the filler neck and use JB Weld on the fitting, and add or replace the filter with a "return line filter" that has a restricted return fitting on it. This is what I did ... not knowing that my problem all along was a defective ignition module. (ok, dumb - shoot me..ahahah).... https://49fordcoupe.smugmug.com/Fighting-Vapor-Lock/
Especially if the gas cap is new and the car quits right at about the same amount of running time every time I'd be looking into making sure that the cap is actually vented. I see that you answered his post further down. Two simple ways to test it. Run it until it quits again and remove the cap and see if air rushes into the tank. It may seem like it is coming out but it would have created a vacuum in the tank. If the gas level is low you might hear the side of the tank pop back out. The other way would be to leave the cap loose or off and see what happens. Vapor lock issues that I have had always have happened while running in hot weather and under a load. But that was a cooler full of Ice water dumped on the intake and fuel pump a 44 ounce cup at a time pulling a grade in Utah in 1977.
There is a filter between the tank and fuel pump, and one between the pressure regulator and the carb