72 240z will not start

[glacier985]

First things first my 72 240z will not start and stay running at all. Since I purchased it almost three years ago it has slowly got harder and harder to start. I'm totally new to carburetors and need some help. I'm checked a few things and got an idea that the carbs are the problem.

Engine (from the documentation I have)

L28 with what I believe is the original L24 head

Some type of Camshaft Upgrade

Header

Port/Polish

SU Round top Carbs

Pertronix Ignition/Coil

To start this winter I replaced the points and coil with the Pertronix parts. My idea was to do this and tune the car up in the spring well come spring and it won't start. I went through the list of things I would do on a fuel-injected car. First I drained and replaced with fresh gas. Next I checked that there was spark, there was a nice blue spark. Then I checked that the carbs were getting fuel, fuel was getting to the bowl and then out the bottom line to the jet (I think that is what its called). Sure enough everything was good so I charged the battery and tried again, no go. Next I sprayed some starting fluid into the carbs and it fired up and ran for maybe 3 secs. Now that is where I'm at and not sure where to go from here.

A few things to note, cylinder number 6 has an issue compression was 50 psi while all other cylinders with 165 - 170 psi. After some tests I believe it is either valve related or head gasket related. I know this needs fixed, but I would like to at least get the car idled on five cylinders before I tear into it. Unless I should do otherwise.

[tlorber]

I just went through this on a '73 with the same symptoms. When choked, the nozzles were not pulling down far enough (if at all) so the mixture was not rich enough. Once I made sure the nozzles dropped, the car started.

Hopefully your issue is as simple.

[siteunseen]

I recently bought a '72 that didn't want to run. After loosening the intake valves to spec and replacing the fuel filter it fired right up.

[Mark Maras]

The problem is fuel related. but checking the valve clearance first is a must do. These carbs are very simple to work on so don't be intimidated. Remove the air filter & housing. While another person operates the choke reach under each carb & check for full movement of the nozzles. With the choke on, grease the nozzles. Check the oil level in both carbs. With the carb intakes exposed, lift the pistons all the way up & let them drop. They should drop at about the same speed & should feel smooth. Pull the float bowl covers & verify that there is fuel in the bowl & it is about 19mm from the bowl rim.(warning, the gaskets will Pringle on you so it's a good idea to get new ones first).Turn the mixture screws all the way up & note the turns. If the float level is close the m. screws will be about 2 1/2 turns down. Let us know.

[bartsscooterservice]

Next I sprayed some starting fluid into the carbs and it fired up and ran for maybe 3 secs. Now that is where I'm at and not sure where to go from here.

QUOTE]

Sounds like a carburetor problem then.. it's not getting fuel.

Also check your ignition timing.

[240260280z]

I concur with Bart. btw I just resolved a 510 no-run problem where there was spark on cranking and none with the key on run so make sure you have 12V to the coil + with the key in start and in run.

[bartsscooterservice]

@ blue: at my work on scooters, I sometimes find the problem that you see a spark outside the engine, but they spark is to weak to fire under compression in the engine. Then when changing the coil it fires right up. Makes you believe you have a good spark..

I also had when using brake cleaner fluid sometimes it fires a few seconds with a bad coil, because it ignites more easily than gasoline.

Edited May 25, 2014 by bartsscooterservice

[240260280z]

[glacier985]

I just went through this on a '73 with the same symptoms. When choked, the nozzles were not pulling down far enough (if at all) so the mixture was not rich enough. Once I made sure the nozzles dropped, the car started.

Hopefully your issue is as simple.

So the car is running thanks to this right here, when pulling the choke lever they were not moving the needles much at all similar to your issue. After some moving by hand I was able to loosen them up enough to get the car started. Now its onto to fix whatever issue I have with cylinder 6 so I can get my z back on the road.