'73 240z not starting

[CJK '73 240z]

Hi, I am new to the forum... just bought a '73 Z a couple of weeks ago. I does not start (I bought it very cheap). It had been sitting for several years. The previous owner was not very chatty re: the history... other than to say that when he parked it, it ran. The exterior is in reasonable shape but inside, the console has been removed and the glove box is missing... tell tail signs of some electrical issues. I have replaced the battery and it will turn over but will not fire. I have also replaced the plugs... nothing. All guages are out except for amps. I have replaced all the fuses in the fuse box... still no fire. The third fuse from the bottom on the right side of the box (tail light - I think) is melted and the clip holding one end of the fuse has broken loose; however, the wire is still connected. I have spent quite a lot of time reading threads related to wiring, fuel pumps, inline fuses (which I can't find), etc but have gotten nowhere. I should also mention that I don't hear anything (fuel pump humming) as I turn the key. The question I'm throwing out is where should I start??? Given the condition of the console and glove box, the absence of dash function and the lack of fuel pump hum, I am thinking electrical... concerning since I have a very limited knowledge of automotive electronics:ermm: If anyone has any suggestions, please let me know. Thanks,

CJK

[WarrenZ]

Hi

It has most likely got a mechanical fuel pump, on right hand drive cars it is on the right hand side of the engine at the front.

First thing I would check is whether you are getting a spark at the plugs. Take out one of the plugs, connect the plug lead to it and hold it near the block while you crank the engine. You should see the spark plug fire. If no spark, check points in distributor and see what they look like. You can also check if there is spark coming from the coil. Pull the centre lead out of the distributor and repeat the same process for checking the spark at the plugs. If there is no spark there you are back into the coil, ballast resistor and the wiring.

If you have spark at the plugs it is more likely a fuel issue. Pull the fuel hose off to a carby and see if fuel is coming through (catch it in a can).

See how you go with that.

Warren

[JimmyZ]

First you need to figure out whether it is a fuel or ignition problem.

A quick way to see if it is a fuel problem is to try some starting fluid. Remove the air cleaner and spray a quick shot in one or both carbs. (Spray too much and you might get a fireball/loose some hair) If it runs momentarily on the starting fluid then the fuel system is at fault. It might be that your carbs are gunked up. Do you have the simpler SU carbs or the ones that came with a '73?

If it doesn't run on the starting fluid then ignition or an engine mechanical problem exists.

To check ignition...

Lay a clean plug/wire on the valve cover (Or good ground) and crank. Look for spark. (See link below) If you suspect something upstream such as a wiring harness or ign switch you can always run a wire from the "+" terminal of the battery to the "+" terminal of the coil. The engine needs to be turning when the ignition is on in this manner or by the switch otherwise you will burn your points. In other words, do the "+ to +" thing just long enough to verify whether the ignition system works.

Here's a link I made... or started to make for the basic 240z ignition..

http://warbuddies.homestead.com/240Zignition.html

[JimmyZ]

Warren beat me to the post.

[EScanlon]

No Tach? Since it's a 73, more than likely there is no Ignition connection to the Coil.

Without that all you'll do is wear down the battery.

Look for the 4 wire Tach connector with a Green/White and a Black/White pair of wires and connect those two to bridge the connection and send power to the coil. (The Tach Connector will also have a Green and a Black wire as part of those 4 wires.)

2¢

E

[kenz240z]

Most likely your '73 has an electric fuel pump mounted under the car back by the fuel tank on the passenger side. There is a fuel filter inside of it that you should check. Mine was filled with silt/sediment from the tank. My '73 had been sitting for 7 years before I bought it. I'd also recommend replacing all the flexible fuel hoses that connect the electrical fuel pump to the tank and the hard fuel line.

Follow the recommendations that Warren, Jim and Enrique have provided and you should be in good shape. A few other suggestions: replace the points, rotor and cap in the dizzy. Change the oil and oil filter. Drain & refill the radiator. Replace the water pump and thermostat. Replace all belts, hoses and flexible fuel lines. Replace the mechanical fuel pump and the fuel filter on the passenger side inner fender. Adjust the valves. Clean the carbies as best you can WITHOUT taking them apart or fiddling with the linkage between them. Oh, and a new air filter, too.

A few more things if your car has the round top SU carbies: Remove the banjo fitting from the float bowl cover on each carby and clean the filter screen inside. Then remove the float bowl cover, drain (if needed) and clean the inside of the float bowl (unless you have very early SU's, there should be a drain plug on the side of the float bowl). Inspect the needle, seat and float for any problems. Adjust the float (do a search, I can't remember the measurements...). Put the float bowl covers back on with a new gasket - make your own or buy new ones. Remove the dipstick on the top of the carby dome and remove any old oil that is in there and replace with clean 20 wt oil. Check to make sure the fuel nozzles aren't stuck or frozen in the carbies. Pulling the choke lever back should pull the fuel nozzles down about 1/4". If the fuel nozzles are stuck, plan to remove the carbies for thorough cleaning and a rebuild (or replace with refurbished ones from ZTherapy).

Hopefully that will cover most of it, I may have forgotten a few things. But, these are all items to consider before you run the engine for any length of time.

Once you get the engine running I would discourage you from attempting to drive the car until you have addressed the following:

Brakes

Steering

Suspension

Clutch (if equipped)

Transmission

Lights

Horn

Wipers

Seat belts

In short, you should insure that your car is SAFE to drive before you ever take it out on the road.

Keep us posted with your progress.

[CJK '73 240z]

Thanks for the great info everyone!!! The learning curve has been steep but a heck of a lot of fun. This afternoon I sprayed some starting fluid in the carbs and she fired up briefly - a small victory. I checked the fuel lines running to the carbs and they were bone dry. I also checked the line running into the fuel filter and it too was dry. My question then is... should I begin replacing fuel lines and pumps or should be looking into an electrical (fuse) issue related to the lack of fuel pressure? As I indicated earlier, I have no gauges - in some other threads it's been suggested that this may be related to fuel pump problems. Thanks again to everyone for the great advice!!!

Cheers from Canada! CJK

[JimmyZ]

You might want to drain the tank to get rid of any crappy fuel first. Pour a little fresh gas in to flush. (Maybe a quart) Do this all outdoors and on a windy day to avoid a fire/explosion hazard. Serious about the safety thing.. You want to see 2008 right?

As mentioned above it would be a good idea to replace the mechanical pump and filter. The rubbers inside the pump are probably cracked. Another problem might be that the fuel rail could have crud in it. Once you get gas flowing past the filter remove the fuel return line from the rail and check for good flow through the pinhole. The pinhole provides a restriction needed to keep pressure in the system so don't drill it if it's clogged. Rather flush the rail repeatedly with laquer thinner and blow with compressed air to clear it. Laquer thinner works VERY quickly on varnish but can also eat/damage plastic or rubber. Don't run laquer thinner through the carbs or any part of the system other than metal lines is what I'm trying to say.

It's also remotely possible that the electrical pump is toast. Run some juice to it and see if it comes to life. Easier yet, check for voltage coming from the leads with the ignition on. Make sure there is no raw fuel present or the spark could ignite the gas.

If there is no voltage you could always temporarily rig the pump with some wires. Use a FUSE! This could help you get past this hurdle if present. I know you just want to hear it run.

I recently de-cruded (tech term) a lawnmower tank that had been sitting for tweleve years using LT. After sitting overnight, the tank was down to bare metal even though the varnish was 1/8" thick!

If you have the simpler early model SU's you can fill the fuel chambers 3/4 full of gas. This will run the car long enough to prime if the mech pump is OK. If you have the 1973 carbs.. well.. you're going to do some cranking.

[JimmyZ]

BTW

My Z was down for a few years. I wasn't surprised to find that the mechanical fuel pump's rubbers were toast. What was surprising were the flakes of white mineral like stuff which in turn clogged my rail. It seems that either the fuel left it behind or the fuel had caused a reaction during drying.

Either way I had to flush my fuel rail a couple of times before all was well. Replacing the pump, filter and rubber lines exorcised this little nuisance.

2c

Jim

[CJK '73 240z]

Thanks for the tips so far, I think I am narrowing things down. I tested the electric fuel pump today and found that it has no current running to it... I'm thinking that's a problem. As I indicated earlier, the dash and console condition lead me to believe that the wiring has been an issue prior to me buying it. I traced what I belive to be the fuel pump wires from the passenger side kick plate but did not find an inline fuse (as I have read, there should be an inline fuse somewhere between the kick plate and the fuse box) - it just connects into a bundle of wires behind the radio. Here's another puzzle, once I completely removed to console I found an extra connector (unconnected). It has one green and two black wires... but where does it go/what is it for? and could it be related to the fuel pump? I have included a picture of the unidentified connector. I anyone has suggestions I would greatly appreciate them. Thanks and happy new year.

CJK

[WarrenZ]

Hi,

My right hand drive 73 240 does not have this plug. In looking at the wiring diagram for the US model it could be related to the auto transmission, either the kickdown switch and solenoid or some sort of thermo switch.

From what I can see the other side of the inline fuse for the fuel pump gets it power via the ignition switch (Black white wire) and is common with the power side (black white wire) of the 20amp "common fuse" in the fuse box. I would check if you have power at this point in the fuse box with the ignition switched on and if so you need to find that inline fuse as it is most likely blown.

Warren

[EScanlon]

Not sure what the connector you have connects to or for.

In your photo, you can see the Fuel Pump Fuse connector just upwire from the one you are holding. The Fuel Pump Fuse basically bridges the two wires coming to it. See the attached photo. Not sure what the "other" half of the connector connects or connects to. There are several circuits in the harness that in vehicles produced during model transitions that did or did not have full functionality. The Fuel Pump circuit is present from the late Series I through ...

But if you'll note, the fuse holder just connects the Black/White to the Green wire with an in line Fuse. It would be easy to say that the other connector is for the Fog Lamps, but that has a different wire color combination. (Green/White and Red, see second picture)

FWIW

E