1.rinsed out as much rust as i can with water and soap from gas tank.

2. dumped 6 gallons of white vinegar into gas tank to eat out remaining rust.

3. went to dismantling yard and got lucky ran into a 78 280z and pillaged the filler neck.

4. found replacement fuel pump at oreilly auto parts and gas cap for 280z filler neck

gas cap

NAPA AUTO PARTS

fuel pump

NAPA AUTO PARTS

no fuel going to carb by the firewall.

1.checked all lines had fuel coming from mechanical fuel pump.

2.filled fuel bowl and engine fired up.

gotta rebuild carbs or upgrade .

any suggestions?

Flat tops or round tops?

Flat tops or round tops?

round tops *i was told these carbs didn't come on the 74's*

They were not OEM on the 74, but lots of people swapped them in because of vapor lock issues. That said, there are a few of us who have no problems with the flat tops.

Get a 72 FSM and start looking through the EF section to see how to tear it down. For reference, it looks like you have 3-screw roundtops. You may want to wander over to the Ztherapy site and get their Just SUs video.

The most important thing you can do with round top SUs is get your float level proper, do that and make sure your float valve is closing and opening properly and it should be no problem getting it to run (at least run poorly) as long as there is fuel getting to the carbs.

Also make sure the pistons aren't stuck and drop okay.

Second on the Just SUs video, it taught me most of what I know about em.

Edited May 3, 201311 yr by Captain_Zeros

Just some notes from a 260 owner... I have the same symptoms if I don't put on my seatbelt. Under the seat, you can disconnect the seat switch which will eliminate your need to put on the seatbelt to start the car. Also, your electric fuel pump in the back by the tank will not kick in until the engine is running at or above 400 rpm.

Edited May 3, 201311 yr by 260zCaliCar

Just some notes from a 260 owner... I have the same symptoms if I don't put on my seatbelt. Under the seat, you can disconnect the seat switch which will eliminate your need to put on the seatbelt to start the car.

However, if you connect the wires at the emergency switch as I described in post 19, you NEVER have to worry about the seatbelt interlock relay failing.

Also, your electric fuel pump in the back by the tank will not kick in until the engine is running at or above 400 rpm.

Not entirely accurate. The fuel pump relay is energized while starting.

Not entirely accurate. The fuel pump relay is energized while starting.

He was right. There are 2 fuel pump relays in the 260Z. One kills the pump when starting and the other kills the pump below 400RPM. Therefore, the electric fuel pump only runs with the car running.

I stand corrected. That's what I get from looking at only the wiring diagram which makes it look like the starter relay was a normally open contact. EF-7 does show it's normally closed.

Back in town , rebuilt carbs .

now the car starts but wont idle.

when the car starts its like its at wide open throttle and my foots not even no the pedal....

help whats wrong and what do i need to do??

things to check in no particular order:

• vacuum leaks
  
• float level is absolutely critical to making SU carbs work good.
  
• make sure your choke linkage isn't sticking open... in fact make sure none of your linkages are sticking. If you take the domes off and remove the pistons you should be able to see the carb jet, if it moves up when you press up here: that means it was sticking in the down (choke on) position and you have things to tweak on in your linkages.
  
• throttle linkage balancing screw
  
• each carb's idle control screw (look down the throat of the carb, all this does is crack the butterfly open a little at idle, does nothing when pedal is depressed) pictured: Tightening it all the way and then loosening it 2.5 turns or so should get you pretty close to a decent idle in a carb that is functioning right.
  
• if there is play in the throttle butterfly shaft you'll have a big vacuum leak no matter what and the carbs are in need of more servicing than I know how to do. Ztherapy can make 'em better than new if you can afford the price.
  
• make sure the pistons drop freely, if they're jammed all kinds of kooky stuff can happen.
  

Speaking of Ztherapy, I highly recommend their Just SU's video. It's all killer no filler and probably 75-90% of how I know a dashpot from a grose-jet.

Edited May 24, 201311 yr by Captain_Zeros
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