Electric fuel pump question

[Pasquale]

Hey everybody,

 

I just picked up my 73 240z last weekend and I'm having a really hard time starting it and when it does start keeping it running.The previous owner said it has two pumps a mechanical one on the motor and an electrical one in the general vicinity of the fuel tank that he had disconnected (reasons unknown). The motor will fire really strong at first then slowly die out from a lack of fuel. I have deduced that the electric unit is to prime the carbs and the mechanical unit continues the flow after that. My question is how integral is it that the electrical unit be installed? I've been researching all week and I really can't find a straight answer. What do you guys think?

 

thanks in advance.. Pasquale.

Edited August 8, 2011 by Pasquale

[beermanpete]

The electric fuel pump was added by Datsun in an attempt to solve vapor lock problems. The car should run with either pump on its own. Mine ran ok with only the mechanical pump. When that pump failed I removed it and installed an electric pump (A Holley, not the OEM type).

 

The first thing to do is determine why the car is not running. If you believe it is not getting fuel to the carbs then check the fuel pressure and flow rate. The difficulty is that the mechanical pump is rated for its pressure and flow at 1000 RPM. At cranking speed the flow should be a series of distinct strong pulses. Pressure should be as rated (3 to 4 PSI) as long at the float bowls are already filled (i.e., no fuel flowing).

[Pasquale]

Well i picked up a new mechanical and electric fuel pump. Im going to install both just because I bet they're both original I guess it wouldn't hurt to put some new clean running parts in my old rust bucket lol. I'll have an update soon and probably a plethora of new questions after wearing out the search feature first of course lol.