Hi everyone 

Here is my situation i bought a 72 240z

That was sitting for many years i dropped and cleaned the fuel tank cleaned out the fuel lines put a new electric fuel pump new filters put 5 gals of 92 octan its now getting clean fuel to the carbs i purchased and installed carb rebuild kit i put new plugs and wires and it is getting spark i fired it up after a oil change and prepped the motor i had to play with the carbs for like a hour to start it had to use quick start to prim it and she ran great for 45 mins or so shut it off now she will not start anymore any ideas or things i should check

P.s the carb next to the firewall sucks in a lot of air the the front not so much?

 

Got spark?  Check fuel filter.  Is gas pump pumping and how much pressure?  Sync the carbs with an airflow meter when it starts running.  Check carb floats,   Dual carbs tend to double the fun of troubleshooting.  Good luck.

Dennis

I cant sync the carbs because it wont fire up anymore the rebuild kit said to adjust the float bowl to 14 mm is that correct or can that be my problem?

The new valves are pretty tough to get right, for me anyway. If you followed the Ztherapy dvd they're way off.  I took me a year to get mine right.  First red flag was the ramps on the floats were at about a 45 degree angle. They should be about level.

You hold the lid upright and blow through the fuel inlet, pushing the float up until the air shuts off.  That'll get you close then rig up a glass and mark that 23mm from the inside roof of the lids. Get it to stop flow at that line.  I have some pictures I can post in the morning.

The new valves are sensitive and won't hold the weight of the floats upside down like the dvd shows. You have to do them right side up.  

Here's the one, lots of ideas and opinions plus a bunch of joking around but something may make sense or a light bulb in your head.

http://www.classiczcars.com/topic/55190-float-level-advice-please/

 

I cant sync the carbs because it wont fire up anymore the rebuild kit said to adjust the float bowl to 14 mm is that correct or can that be my problem?

 

Wow thank you for the information!!!

I will try tomorrow

Thank you for the information

I will try tomorrow

 

There's an FSM factory service manual for your year car on this site somewhere. It goes into SU tune procedure  in detail with illustrations. If you don't have a printer you can put that chapter on a flashdrive and take it to a copy place to print it. It makes the tune way easier when the chapter is sitting on the fender.

Here's another thread that helped me.  It's not the FSM but I did copy and paste the steps and print them out, I put mine under the driver's wiper blade.  Still have that piece of paper.  The way it looks I assume that's the "dirty" part. 

 

The FSMs are in the downloads section. I have it linked in my signature. You can see my signature if you're not on a mobile device.

@Newzowner You might want to say were you live. There may be a knowledgeable member close enough to you that could help. You don't have to suffer alone.

 

 Pull the plugs and check the color. That will give you an idea of the fuel to air mixture on the carbs. Another easier way to check the float levels is, pull the suction chambers (domes), pull the pistons, (be careful with the needles, I always set my pistons on the cowl with the needles sticking thru a cowl slot). With the mixture screws 2 1/2 turns down the fuel level should be about 1/16" below the top of the brass nozzle the needles fit into.

Thank you everyone for the great advice

After reading those threads i think my floats are way off wack

I didnt just get a great vehicle when i bought a z but i got some great people to discuss common frustrations with as well with lots of knowledge thank you

P.s I live in st george utah

I have a chance to play with my z for a couple of hours today hopefully ill get her to feeling better