timh Posted August 19, 2001 Share Posted August 19, 2001 I'm having a problem very similar to one Mikely had with his fuel system. I have a 75Z with a moderate 350, a new holley electric pump/regulator and 3/8" aluminum fuel line. I'm using the stock tank, the fuel pump is mounted just below the stock position (it's within and inch of the tank bottom). The pump is wired with 10ga wire and a Painless Wiring relay kit, it was running at 12.3V when my pressure was down to 4.5 psi. I have rerouted the fuel line through the fender, to the firewall, where the regulator is now mounted, then to the carb, a 600cfm edelbrock. My fuel pressure starts at 7 psi, after about 15 minutes it drops down to 6 psi, at 25 minute it has dropped to 4.5 psi. Can anyone offer a solution? Tim Quote Link to comment Share on other sites More sharing options...
Mike C Posted August 19, 2001 Share Posted August 19, 2001 What have you done to modify the charcoal cannister or venting to the tank? Could well be a vacuum inside the tank. Quote Link to comment Share on other sites More sharing options...
timh Posted August 20, 2001 Author Share Posted August 20, 2001 Would taking the fuel tank cap off eliminate that as a possibility? I've tried that without success. I didn't put the canister back on, that'll be my next step. Thanks Quote Link to comment Share on other sites More sharing options...
Mike C Posted August 20, 2001 Share Posted August 20, 2001 I would have thought it would...I had all sorts of odd fuel problems with my last 240. Acted like vapor lock, so off came mechanical pump and in went a pusher. Still would act like vapor lock, so on went more pump and a regulator. Still on occassion, would stall and act like vapor lock. Switched to a clear fuel filter and lo-and-behold, it was not getting gas on occassion. Shutting off the pump and shaking the car side to side returned proper operation. I sold the car before pulling the tank, but it seems that something was obstructing the pickup in the tank randomly. (I finally learned I could shut the pump off while driving and shake the wheel side to side, turn the pump back on and continue on my way. This trouble only happened about three times a year in the 7 years I had the car.)I don't know if the Z pickup has a "sock" on it like a GM, but that could be a source of partial blockage or something else loose in their or it could be pulling air somewhere in the fuel line. If not in the new part, possibly where the pickup is soldered into the tank. Quote Link to comment Share on other sites More sharing options...
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