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Newzowner

Im at wits end please help

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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?

 

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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

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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?

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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.  

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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

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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.

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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. :)

 

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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. ;)

 

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 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.

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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 

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@NewZowner - Welcome to the group! Not many of us in Utah. I do get down in your neck of the woods during the winter. Some of the best golf in the country is in the greater St George, Hurricane and Mesquite area! Sorry I can't help with your carbs, I got refurbs from ZTherapy for my early 71 this year and the car seems to run just fine without even touching them. Before I had my mechanical problems back in 2003 when I parked my Z for 14 years I did enter my 71 in the Huricane Easter show in 92 and 93. Was subjected to a lot of "rice" comments, but ended up getting a 3rd place trophy in sport cars in 93. I'll be waiting to hear your tales of taking your Z through the Virgin River Gorge. That seems like it would be great fun!

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@ w3wilkes 

I will take it to through virgin river gorge that sounds like a lot of fun

And if you in the area maybe we can play wolf creek or something its one of my favorite tracks in the country and i played from the bay area to main

In regards of the z i found a bad wire in the distributor it looks burnt when i checked spark it was fine but when i ran the motor the other day for about 45 mins i think it burnt then i was trying to tune the carbs without a unsync meter and that wire was on the verge of going out i will continue to play with her after thanksgiving and post some updated when i get back home 

Keep them purring z fans happy thanksgiving

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@newzowner Just a note on gas for your Z... The Maverick at the Washington Parkway exit (Exit 13) sells non-ethanol fuel. I'd recommend you run that in your Z. The non-ethanol fuel stores way better than fuel with an ethanol mix, won't attract water the way ethanol mixed fuel does and is less corrosive on the fuel line rubber sections.

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Looks like there's more ethanol free gas around St George than I thought. These list all Utah and Nevada stations by town. You've got choices in St George, Hurricane, Washington. Also Kanab, Cedar city and Mesquite.

https://www.pure-gas.org/index.jsp?stateprov=UT

https://www.pure-gas.org/index.jsp?stateprov=NV

 

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Hi everyone i hope you had a good thanksgiving

Here is my situation i had some time to play with the z today over the weekend i rebuilt the carburetors again it seemed that i didnt do a great job cleaning the fuel lines because something junked the carbs however i cleaned them out real good rebuilt the carbs i am now getting clean fuel to the carbs i am getting spark to each plug and i can start it for a short time but carb is farting spitting and popping i cant get it to stay started long enuff to time it what could my problems be?

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On 11/16/2017 at 2:11 PM, Newzowner said:

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

It ran great for while but now it doesn't and it spits and pops.  Spitting and popping is often a sign of a lean mixture.  Could be a vacuum leak or it could be the carbs need tuning to add more fuel.  You could do some tuning, but make sure you know where you started so you can go back.

You can get pretty close with ignition timing by eye.  Put the damper pulley mark on 10 degrees and rotate the distributor until the points are just about to open.  Make sure that you're aware of the rotation direction.  Maybe the distributor vacuum advance got stuck in an advanced position.  

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Another thing, how far down are the nozzles?  The initial setting according to everything I've read and watched is 2.5 turns counter clockwise.  You can add more fuel that way too, go 4.5 if you think it's lean and try that.

Did you set your floats with the lids upside down?  At .550"?  I did and had a problem for a year.  The newer needle valves aren't strong enough to set them that way, they won't hold the weight of the float like the Grose jets would.  You have to hold them right side up and blow through the fuel inlet, pushing the float up until your breath stops.  An easy way to get close is to get the float's tang looking like this one.  Mine was raised up like Evel Knievel's Snake River Canyon ramp.

ignore that red circle

Image result for set floats siteunseen classiczcars.com

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