tetert1

I have a 4-72 240Z I found a bullet wire that's hot that goes to the ignition I hooked up my electrical fuel pump to it... it is on the firewall next to the alternator

And My 72 Z was doing the same thing I did about all the same things you did. I bought clear hoses from Amazon 5/16 and quarter inch and fuel pressure gauge and install them so I could see what the fuel was doing to carbs. If you don’t have clear fuel hoses you’re blind unless you have x-ray vision .I was getting air bubbles to theMechanical fuel pump low Pressure and carburetor float bowl’s making the engine run lean and run hot Hot exhaust manifold and muffler.Vapor lock in fuel line I check my timing on my distributor it was set to retard. I advance the timing to 5°or 10• BTDC now the engine runs a lot cooler and no more air bubbles vapor lock So maybe your engine is running too hot and lean because your exhaust manifold is right under your carburetor float bowls Also check your Guide flow valve next to your coil. three-way valve ,blow it out see if you can hear airAnyway that’s what happened to my Z hope this helps..Also it helps to have a half to 3/4 gas in your tank

From the AC compressor clutch I ran the positive wire with a toggle switch to a hot wire. Found some rubber O-rings from O'Reilly's that were close to what was on it..Filled compressor with R134 freon.and it's blowing cold air.

thank you for your help and concern

There is no lever to power on the AC you just turn on the fan switch and turn the thermostat control to the right and a tiny green light comes on and cold air starts coming out the vents so where does the black positive wire from the compressor hook up to? Maybe I need to hook it up 2 a positive wire to the blower fan motor with a toggle switch. When I hooked a positive wire from the battery to the loose black wire from the clutch the green light from the control thermostat box came on

here are some pictures the black clutch positive wire is hanging by thermostat control box ..where does it hook up to? Can I hook it to the blower motor positive wire?

It's a 71 Z with a factory AC it was working at one time. the guy was supposed to fix my gauges and lights and he took out a whole bunch of wires and put some gauges in on the bottom of the glove box I left the car there and when I came back a few weeks later he did all the stuff I didn't even tell him to anyway I'm trying to get the AC hooked up again and running the clutch compressor positive wire comes through passenger side. And it was tied up by the thermostat control box where does it hook up to. I have seen a 72 and it goes in by the driver side and runs up to where the fuse boxes and it does have a fuse in the line.. tomorrow I'll try to take some pictures and show you what I mean on the 71 Z

71Z..where does the positive black wire on the AC compressor hook up to? a mechanic's did some work on my electrical system and left that wire lose. Does it hook up to the AC control thermostat box if it does but were? when I look in the back there's only one red wire hooked up going back torn Center panel. the black wire from the compressor clutch is just hanging there it's been cut. Does it need to be hooked up to the positive blower motor ?

First put clear hoses on your fuel lines to the carburetor so you can see if there's air bubbles vapor lock. Vapor lock will make your engine run lean and will make it die and hot exhaust manifold, Muffler, fuel line ,carburetor bowl ..if there is. Check your distributor and timing.. loosen the bolt on your distributor. Turning toward advance will make engine cooler.. I sent mine from the center of the dial on distributor to the left.. or get a timing light from Harbor Freight $25.. always check the basics first

How would you recommend unplugging the return line.. steam it out add chemicals? Try maybe pressure washing ,maybe a radiator shop might help? Small drill bit?

Like I said my return line on the fuel rail has a pinhole orifice I stuck a needle in it and it's blocked off won't go through is it supposed to be that way

is it possible that air is getting sucked in at the Overflow tubes on the float Bowl back down to the fuel line? I stuck a needle in the orifice in the return line and it seems like it's plugged

while I'm running the engine I place my finger on the Overflow tube on the float Bowl it was sucking air on both of them.. when I put my finger on it ,engine try to die. Also check my fuel return line at the orifice tiny pinhole try to stick a pin in it wouldn't go in something very hard like metal is it supposed to be like that or is it supposed to be free of obstructions??

my 72 Z has a short one on the front and a long one on the back I also took apart the mechanical fuel pump while on the engine and check the diaphragm it was good.. started the engine ran good for 10 minutes and then bubbles started appearing starving. Carburetors ..are there any good videos out there showing you how to tune 240Z carburetors the right way ? I might have to take it to a z mechanic anyone know a good one in the Houston area

thank you I appreciate your reply

I took the back carburetor float out to inspect it by the firewall it has a long needle in it like the pictures you have on the float the one on the left it's the one I had in the rear carburetors by firewall..if you are saying the long valve goes on the front carb than mine are on wrong.. . is that the right one? yes the AC works a guy just put 13 freon in it with the fittings and it cools good since before summer. . that mechanic said those AC compressors are indestructible hadn't been used since 1981. license plate

also I got a gas can and ran a hose from the mechanical pump to it and still getting air to the carburetors and when I shut the engine off air is coming back towards a gas can so the fuel pump must be sucking air .. ever heard of mechanical fuel pumps doing this?

Thanks for the great pictures also the float jet needle that is longer goes to the back carburetors and the short one go to the front carburetors right??

thanks for the pictures that explain the different sizes in the floats. Are there filters in the float bowls you need to change too or check?

tomorrow when I have time I'm going to try the clear hose..thanks

thank you for these pictures my carburetors are just like these it has a n otch that's in the way when you try to pull floats head. When you change the needles on the float bowls is there there one for the rear and one for of Front... different ones? also can you purchase any that have a greater flow rate? I have blown real hard into new and old needles and hardly any air comes out. so maybe I need to buy one with a greater flow rate

yes what's the trick to get the floats off and put back on I had a hard time getting them off and a harder time putting them back on I didn't want to damage them. a guy that works on them in the Houston area said to set them at a quarter of an inch from the top? I'm also trying to find a fitting that I can put on the tank drain plug so I can connect the fuel hose. Thanks for all your help

Well I just ran a braided fuel line from the tank to electric fuel pump in the engine compartment not as much bubbles as before when the engine gets hot the clear fuel hoses next to the engines start bubbling go to the rail and then to the Su carburetors the clear hoses that go to the carburetors are almost empty barely getting fuel what do you recommend should I set the float bowls. Hoses on top of the float Bowl that go to the air cleaner are sucking air in. when I put my finger on it to stop the air the carburetor wants to die.. gasoline in the clear fuel lines are getting too hot next to the engine and the gas is turning to Vapor I think. I'm going to get a can of gas put the hose in it and see if I get any bubbles in the carburetor fuel lines and see if they fill up like they should

thank you so much for the reply I'm going to check the height of the float and someone said to replace the hose on the bottom of the floats they get old and suck in restricting fuel