zclocks

Dave, A couple more photos of what My 75 looks like. No Ground wire attached to the terminal block. Mine is bone stock Ron

Dave, I have a very early 75(1/75) and it looks like the FSM, at least the connector ground. No additional wire (green) coming from the terminal block. My green wires go into the harness! Ron

If you really believe it's not that bad I'd hate to see a really rusty Z. Rust never sleeps and by the time it's this visible there are real problems. Well that's your opinion and this is mine.

WOW! I have a 75 and that car is really in bad shape. It's what I would call the Datsun submarine---It's been under water most of it"s life and 58K miles? More that likely it has 258K on the car. I would be hard pressed to go higher than $500, honestly, but your better to walk away. You will put $25k into that car just to make it safe to drive and that's you doing ALL the work. I've seen several really nice cars lately for about $5k. They are out there just be patient. Ron

S30 Grit Yep, I tested my new switch and it was a solid connection through the complete range of the "Start" portion of the switch. No sweet spot just continunity. Ron

S30 Grit, I'm with Dave WM. I had the same problem your having and it turned out to be the ign switch. Perform the testing , out of the car, as Dave's video mentioned earlier and pay close attention to the resistance in the start position. Mine was OK on several tries in the start position, but not consistent.

Len, very cool! So is this a program you developing? I wish I had something is see whats going on with my beast. BTW my voltage is being sucked down by the ignition resistor or what ever is hooked to the IGN wire on the ign switch. when I disconnect both of these the voltage jumps back to battery voltage. Now I just have to discover why! Ron

Len, Just to be clear I disabled the starter per the manual to make the measurement at pin 4 . I measured the voltage at W47 and the voltage is 9.8 vdc. However, the motor starts right up and runs very nice. I did notice that the fuel pressure was at about 5 psi before I started the car. Not sure where the leak down is, but at least it starts. Ron

Superlen, There shouldn't be a relay(switch) in the path from the Ign start to pin 4. It's a straight in and out connection to the control unit(pin 4).I have a couple FI relays and will measure this path. The connections are 86 to 86a of the FI relay or am I missing something. Maybe the cold start valve and thermotime swithes are pulling down the voltage? They are connected to connection 86 on the FI relay. I'm almost tempted to relocate the FI relay . It's a PIA to access. Ron

Just an update as what I found with my start problem. Actually all of you were correct. I went back and reviewed my data I took on the ECU connector and found pin 4 voltage was low, 9.6vdc. My battery was low, 11.8 volts so I recharged and took readings at pin 4 again and it was still low, 9.6 vdc. So I started at the ign sw and worked my way down to the connector on the FI relay. The ign switch was open or a momentary resistance reading on bench testing. Luckily I had a new switch and I verified the old switch was bad. I reinstalled the new switch and again checked for battery voltage at pin4 and it was still 9.6 volts? If I held the key in the start position for 60 seconds the voltage would rise to about 11.4 volts. I connected everything up and started the motor. It started right up 6 times in succession. I let the motor get to full operating temp and it 's running great and very smooth. In addition the vacuum increased from 18 hg to 21 hg? BTW I did replace all my injector connectors several months ago and verified each is firing consistently. I installed new plugs, fuel pump, wires, cap/ rotor, checked timing, and adjusted valves several times. I'm not complaining , but I still don't understand why I have 9.6 volts at pin 4 going to the ECU at start. Appears to me that something something is pulling the voltage down. Maybe this is normal , yet the FI manual says it should be "battery voltage". I did check the relay pins 86a to 86 and there is no resistance and yet I have 9.6 volts output. Before I declare victory I will try and start the car from a dead cold start and see if that makes any difference. Thanks again for all the great comments and help....Ron

Len you are correct on what is happening. I wasn't sure what happened during the crank sequence or where the input was to tell the ECU to supply fuel. The engine will turn over during the start sequence, there is spark, but no fuel. I used the cold start injector to to just get the motor started. Once started the motor runs without a problem. I still might have a small leak in my injectors , but generally the fuel pressure stays at 32 PSI overnight and several days after the motor is turned off. Actually, the pressure is at 40 psi when the motor won't start. As soon as the motor starts the pressure drops back to 32 psi and maintain that pressure. I will check pin 4 of ECU and see what I have . Dave thanks for your input and I will check my ignition switch. Zed the fuse link I was talking about is the Green one. The 75 has 2, one Black and One Green. I did notice that one terminal of the Green was hotter than the other so I need to investigate that. Thanks all for your inputs and will let you know what I find. Ron

Ok, My basic problem is my 75 280z will not start. A couple of months ago I had a similar problem, but fixed the issue by replacing the fuel pump. Through out the summer is was hot and not a problem starting the car. First crank and the engine started right up. The first cooler day, below 95 F and the car will not start. The fuel pressure is 40 psi when cranking and 34 psi when running, when car is running the vacuum is 18 mHg, I can get the car started by actuating the cold start injector.This pumps in a small amount of fuel and the car starts right up. I did go through all the measurements in the FI manual and discovered that there was a bad connection at the TPS. This was corrected and the car started right up. So I shut down and tried to restart with no luck. I did go through all the rest of the measurements on the connector of the control unit and everything seems OK. If I had to guess I would say the control unit is not activating the injectors or is not receiving the correct input. Why then does everything work when a small amount of fuel is added at the AFM ? The only other observation is that the green fuse link is getting hot to touch which I believe supplys power for the AFM? Any inputs would be appreciate. Thanks ...Ron

Hey Motorman, Does the Fry's in SD look like it's going out of business? I went to Fry's in Fountain Valley a couple of days ago and the store is really empty. I guess Amazon and the other on line stores have really put the hurt on Fry's

Thanks for posting my article. I've attached a photo of a random 240 clock , which is the one that Jeff has, and this is what causes most the 240 clocks to stop. I have worked on many 240 clocks over the years and it's always the same thing. If you add oil this is what you will end up with. If you try to clean things in place you can't do a very good job and you will damage parts. There are plastic parts in the clock (some plastic motors in later 240 clocks) which can be attached by several cleaners. I use only IPA (alcohol) which does a good job, but you need to scrub the parts to get the gunk off . The 280 clocks have a completely different design which uses plastic gears against metal. If you oil on these parts you can degrade the plastic over time. There is nothing in this clock that needs be oiled. The 2 main rotating components are metal against nylon. Nylon is self lubricating and it shouldn't be oiled . Again this clock mechanism needs to be disassembled and cleaned, not oiled. The main failure of the 280 mechanical clock is the circuit board. I do repair these and sell them on my web site. Anyone can usually repair either of these 2 clocks, it just takes time and patience or you can send it to me. Just my 2c.....Ron PS: The first photo is the 240 clock and the second is the 280 clock

View Advert 280z coil bracket Looking for the coil wire bracket in photo. Please pm or e-mail if you have one for sale. Thanks....Ron Advertiser zclocks Date 07/20/2019 Price Category Parts Wanted Year 0 Model 280z

FOUND SMOKING GUN!!!! I finally found the source of my miss and sometimes backfire thru AFM. With all the things I had done I didn't look at the spark at the plugs. So...... I removed the spark wire at each plug, plugged in a spare spark plug and started the motor. Each plug was firing, but VERY weak. To cut to the chase the ignition coil was the problem. Let me rephrase that....I was the problem. I remove and replaced the coil many years ago for whatever reason. The Primary side coil resistance is supposed to be 0.40---0.55 ohms, per service manual for the 75. The Fire ball I put in there many years ago was 1.6 ohms. This might not seem to be a big change , but when I replace the coil with a "Flame-thrower -2" what a difference. The new coil has a primary resistance of 0.6 ohms , but try and find a coil today which is 0.4 ohms is not possible. I know I have my OEM coil , but at the moment I can't locate it .BTW this new coil is used with the OEM ballast resistor. This is a good day!!! PS : I should give credit to a u-tube guy with a site called "Restoration for beginners". He seems to have good understanding of basic mechanics and after watching his segment on ignition systems, which covered coil replacement, he ran into the same problem with selecting coils. Oh yea his car is a 78 280z.

View Advert 75-76 280Z Clock For sale is a very nice 280z clock that keeps excellent time. The circuit board was rebuilt , mechanical internals cleaned , lens polished , set knob re-blacked and lamp replaced. Thanks for looking......Ron Advertiser zclocks Date 07/19/2019 Price $155.00 Category Parts for Sale

You may have just ruined the clock motor and the other bearing parts made of nylon and plastic. Most brake cleaners contain Tetrachloroethylene , ACETONE and chlorine all of which are great grease and oil removers, but detrimental to most plastics. Just a FYI

View Advert WTB Quartz clocks WTB clocks from 77-78 280z and 79-83 280zx . Please e-mail quantity and price. Thanks.... Advertiser zclocks Date 07/17/2019 Price Category Parts Wanted Year 0 Model 280z

Hey Dave, I was going thru a few boxs of Z parts and found a 75 transistor Ignition. It's completely made by Hitachi . They were one of the big part swingers of the day. I'm impressed with the design and construction. Looks like the main power transistors were also from Hitachi. As soon as I can i'm going to install it and see if it makes any difference in my car. If not then I could have a spare or something else to repair.

Dave, Yes, caps have a limited life and so do power transistors. No telling what material they used. If I can get a transistor unit I'll see about replacing the transistors and caps. Ron

Yes, I should know better. I've seen so many corroded connectors on clocks that I just replace every wire /connector. The thing that fooled me is that the connectors didn't look bad, but corrosion is resistance. Thanks again for the input. Ron

Dave you are correct there are 2 transistors in the control unit that are associated with the pulse to the injectors (FSM EF-51).One transistor is associated to injectors 1-2-3 and the other with injectors 4-5-6. I did this check with the 3 volt lamp as indicated in the manual and both transistors check out. This isn't an exact performance evaluation , but rather an overall output check. Funny I remember many years ago I had a lamp that was provided with a FI meter I purchased and no explanation of what it was for. I don't know what happened to it, but that was the lamp as mentioned in the manual. I also pulled the dropping resistors and cleaned everything including the connector contacts on both sides. All the resistors measured 6.5 ohms. After I reinstalled I checked that the power relay was working and there was battery voltage at the control unit pins for each injector. The car is running MUCH better and no backfire thru AFM. The drop outs are farther apart and very small compared to previously. I went back and retested with my Colortune unit and the visual blue flame is much better on cylinders 1,2,3. There are still some drop out or miss fires, but not as many. The intensity of the Colortune flame is much brighter. Cylinders 4,5,6 are unchanged, bright in color intensity and no drop outs. So, I think part of the problem may have been with the connectors on the dropping resistors or the control unit connector. What I am going to do is remove and clean all connections on the distributor, transistor ignition unit, and injectors. All my injector connectors were replaced about a year ago and I still have to replace the AFM connector. It looks good but the boot has deteriorated. I would like to dig into the transistor ignition unit and see what's going on there. I need to hunt down an OEM unit for testing. Anyone have a spare they would like to part with? I still believe there is a slight problem, but I think I'm on the right path. Thanks for all the inputs it's really helped. Ron

I haven't swapped injectors, not my favorite thing , but that's just about all that's left. My car use to idle very smooth and had quick throttle response. I know there's a definite miss in 1-2-3. Could be the injectors not working correctly although they sound good . What are the chances that just 1-2-3 injectors are bad? Ok, thanks for the input and I will proceed with my quest. Ron

Thanks Mark. I'll take a look at all 3 again. Yes, the plugs are BP6ES, NGK plug wires and Nissan cap / rotor.