SU carb/fuel pump problem!!!

[Guest bang847]

Hey guys, My buddy just got a 240z.. it barely made it home... oh well... this is the problem....

this car has a 5psi electric fuel pump... when the ignition is on the pump goes on but then it pumps gas right out of the SU's..

Leave the key on with car off and gas dribbles out the carb horns...

whats wrong??

[jimzdat]

Sounds like float levels are set way off, or you've got a float/needle valve assembly that is stuck, and not shutting off the fuel supply--a 5 psi pump should be OK, at least mine seems to work fine.

 

Pull the tops off of the fuel bowls; make sure there is nothing causing the needle valves to stick (if you can get rebuild kits, just replace them--ideally with Grose jets from ztherapy) then make sure your floats are set to ~9/16"--put it back together, and see what you get.

 

Remember, the float level must be below the top of the nozzle in the base of the carb body--draw an "imaginary" line horizontal across the bottom of the carb throat--if the fuel level in the bowl is above that line, it's just gonna run out the nozzle and onto the ground.

[Mike C]

You might get away with a 5 psi pump, but pressure should be 2 1/2 to 3 psi. Get an adjustable regulator. Chrome job can be had for about $25 with a dial marked in 1 psi increments from 1-5.

[Guest bang847]

Well I took the float bowl cover off and shook the float.. That stopped the dribbling... But the car wont start... I can see wet plugs and all but it seems not to fire... Ignition should be fine because it has a optical ignition system...