The problem: Every time I turn on the ignition, I get a different fuel pressure to the carbs.
What I've done: The fuel system is virtually new. There's a new "sock" on the fuel pick-up tube in the tank,(the tank is clean & no water or trash floating around) I'm using a low pressure Carter 12V fuel pump. The line from the pump to the pressure reg is new. The fuel line goes in the bottom "in" of the Holly regulater. I have a fuel press. gauge on one side "out" and a fuel line to a dual carb block on the other "out". I've tried three different regulaters. The fuel line from the tank isn't anywhere near the exhaust, so I'm not developing a vapor-lock. The tank cap is properly vented (no vacuum in tank) I'm not useing teflon tape.
I can set the press. to 2 1/2 psig, run around a little and the pressure will creep up to 4-5 psig. If I reset the reg., the press. may or may not stay. It sometimes falls off to virtually nothing. The fuel lines go from the block on the fire-wall to the carbs which are on a Thickstun high rise so there's not enough heat there to be a problem. I keep going back to the reg. but it's so simple, (a ball-check, a pin under a diaphragm, a spring, and an adjustment screw.) I don't think it's the reg. but I can't come up with anything else. The entire system is clean. The one thing I am suspect of is a filter between the tank and the pump. The filter is new, and the pump manufacturer says if I bypass the filter I void the warrantee. Do any of you guys run a filter upstream of the pump? Would this cause the problem I described? If the filter was the problem, I could understand the press. falling, but it'll get higher more often than lower. What's up with this?? <img src="confused.gif" border="0">
What I've done: The fuel system is virtually new. There's a new "sock" on the fuel pick-up tube in the tank,(the tank is clean & no water or trash floating around) I'm using a low pressure Carter 12V fuel pump. The line from the pump to the pressure reg is new. The fuel line goes in the bottom "in" of the Holly regulater. I have a fuel press. gauge on one side "out" and a fuel line to a dual carb block on the other "out". I've tried three different regulaters. The fuel line from the tank isn't anywhere near the exhaust, so I'm not developing a vapor-lock. The tank cap is properly vented (no vacuum in tank) I'm not useing teflon tape.
I can set the press. to 2 1/2 psig, run around a little and the pressure will creep up to 4-5 psig. If I reset the reg., the press. may or may not stay. It sometimes falls off to virtually nothing. The fuel lines go from the block on the fire-wall to the carbs which are on a Thickstun high rise so there's not enough heat there to be a problem. I keep going back to the reg. but it's so simple, (a ball-check, a pin under a diaphragm, a spring, and an adjustment screw.) I don't think it's the reg. but I can't come up with anything else. The entire system is clean. The one thing I am suspect of is a filter between the tank and the pump. The filter is new, and the pump manufacturer says if I bypass the filter I void the warrantee. Do any of you guys run a filter upstream of the pump? Would this cause the problem I described? If the filter was the problem, I could understand the press. falling, but it'll get higher more often than lower. What's up with this?? <img src="confused.gif" border="0">