Car idles with mixture screw seated

[clarkedj]

I have a 1978 Spider 1800CC with a 32 ADF carb. I upgraded the fuel pump from mechanical to Electronic. The mechanical failed. After the addition of the new fuel pump the car started to run rough. The specs on the pump say it provides a pressure of 2.5 to 4.0 psi. The car idles with the mixture screw fully seated. Previous posts say that the engine is idling on th main throttle I believe this is so as I can see the gas coming through the jet at the top of one of the carb. Do I have to reset the linkage? If so does any one have a procedure? Should I put a pressure regulator in the fuel line to reduce the pressure? Any ideas would be very helpful.

Thanks

Ed Clark

[So Cal Mark]

make sure the idle speed is correct. Measure the fuel pressure, if it's okay, check the float level, and make sure the needle and seat seal when the float is up

[clarkedj]

SoCal,

I will get a gauge and measure the pressure. If the only change I made to the systems is the e fuel pump would I really have a problem with the seal of the needle and the float level. I would think that would have showed up before the e fuel replacement. Car was running beautiful before the fuel pump replacement. Thanks for the info.

Ed

[So Cal Mark]

I would think the pressure is just too high, but it could be within range but higher than it was before, aggravating a leaky needle and seat or sinking float. Does your carb have a fuel return line on it?

[clarkedj]

yes

Ed