1981 280zx will not start

[Eric280zx]

42 minutes ago, siteunseen said:

I would take a screwdriver handle and tap on the injectors to free up a stuck magnet. I bought a motor with a bad carbeurator and the oil was half gasoline from the stuck carb float dumping all that fuel on the head then it drops down the front cover/timing chain hole straight into the oil pan. The plus side, if you could say that was the gas had washed the head/valve train to look like brand new. But it's not good especially on the valve seals.

You can get a piece of hose to use as a stethoscope to hear the injectors clicking. Whichever one doesn't click is stuck, tap it until it starts clicking hopefully or you may have to replace it.

I have the fuel rail removed right now with everything else connected and I'm going to switch the key just so it starts priming, got the idea from Dave WM. I'll observe if gas is leaking out, should I expect very little or none at all? If it's an obvious leak I'll tap it in hopes that it stops. 

[Eric280zx]

37 minutes ago, Dave WM said:

don't forget to check the cold start injector.  Pull it out of the manifold and look to see if its leaking, in warm weather (over 70f) it should not spray, and it should only spray when the key is in the "Start" position even when its cold. Often times people goof up the bullet connections for the temp sensor for the EFI and the cold start thermotime swtich, make sure they are correct.

Ive heard of people talking about the cold start injector but never gave it any thought, I'll locate the injector and see if it sprays, it shouldn't pray like you said because where I am it's 78 degrees, then I'll have a look at the connections to see if it's correct. 

[Zed Head]

"I have the fuel rail removed right now with everything else connected and I'm going to switch the key just so it starts priming, got the idea from Dave WM. "

 

That's a good idea.  Is the CSV out too?  Watch all seven.

There's no prime pulse on 1981 I think.  That came later and even then it often doesn't work.  Disconnect the starter solenoid wire, and turn the key to Start.  The engine won't turn but the pump will get power.

Edited September 28, 2017 by Zed Head

[Eric280zx]

40 minutes ago, Zed Head said:

"I have the fuel rail removed right now with everything else connected and I'm going to switch the key just so it starts priming, got the idea from Dave WM. "

 

That's a good idea.  Is the CSV out too?  Watch all seven.

There's no prime pulse on 1981 I think.  That came later and even then it often doesn't work.  Disconnect the starter solenoid wire, and turn the key to Start.  The engine won't turn but the pump will get power.

So I primed the engine and I can hear the presssure regulator working and no leaks on all seven. My outside temperature is 73 degrees and when I cranked it the only one that sprayed was the cold start valve ( cold start injector). I'm going to do it without he starter, I didn't read that till now 

[Eric280zx]

okay so, I disconnected the starter and when I started it, none of the injectors sprayed but the csv ( cold start injector) did and it sprayed for over 15 seconds and it would've easily kept going. Is it supposed to do that or is that what's my problem? Could be the temp sensor misguiding the csv 

[Zed Head]

It's supposed to spray until the thermotime switch heats up and opens the circuit.  The engine should have started on the CSV fuel.  Maybe you have bad fuel.

[Eric280zx]

7 minutes ago, Zed Head said:

It's supposed to spray until the thermotime switch heats up and opens the circuit.  The engine should have started on the CSV fuel.  Maybe you have bad fuel.

I've cleaned the fuel tank, added a new fuel  filter, cleaned rail, and injectors. Then I put 5 gallons of regular gasoline. Then every time I crank it, spark plugs get wet with fuel. With the test I did, none of the injectors sprayed just the csv. Other forums say it should've only sprayed for 2-12 seconds, could my thermotime switch be bad? 

[JSM]

Something doesn't make sense. You know it runs on starter fluid and the injectors are not firing. 

Have you confirmed The fuel pressure off the rail yet? Also have you confirmed the fusible links by the batter for the EFI is good?

I'm really confused how your getting gas in the oil and it won't start, but will start with starting fluid. If it was flooding it wouldn't run on starter fluid and all the extra gas. 

[Eric280zx]

2 hours ago, JSM said:

Something doesn't make sense. You know it runs on starter fluid and the injectors are not firing. 

Have you confirmed The fuel pressure off the rail yet? Also have you confirmed the fusible links by the batter for the EFI is good?

I'm really confused how your getting gas in the oil and it won't start, but will start with starting fluid. If it was flooding it wouldn't run on starter fluid and all the extra gas. 

The engine ran for 5 seconds the very first crank by simply adding starter fluid (engine was completely dry) so once this happened I did some things to the fuel, spark, and compression to all be good but it seems like every time I crank it afterwords, it floods and spark plugs get wet and the possibly faulty or misinformed CSV is just pouring gas making its way through the timing chain, crankcase, and oil pan. I have not checked the fuel pressure since I am already getting too much fuel and didn't think it'd be a problem but if it can help determine the problem I can definitely do it. Where is the fuse from the battery to the EFI? 

[JSM]

You can always cap of the CSV for the time being. Slide a bolt into the hose leading to it. 

The fusible links are in a little box next to the battery. 

 

[Dave WM]

do what JSM said, disconnect the CSV hose and cap it for now. should not be firing at all unless its cold where you are. At lest you will stop flooding the crankcase with gas (I would drain the oil and refill again until you figure this out, no reason to destroy the bearings in case is starts from gas thinned oil). you need to get to a point where NO fuel is spraying with the key in start and the starter solenoid disconnected. You should just see the pressure jump to 36 psi, then release the key from start and it should stay there at least for several minutes. How well it holds pressure will tell you if you are leaking fuel OR the fuel pump check valve could be bad. Regardless, get that working before moving on. Its best to resolve one system at a time rather than jumping from one magic bullet to another. Don't start replacing parts unless you know they are bad, doing so only adds more variables that can cause it to be harder to figure out what is wrong.

Next you need to review the FSM and sort out the EFI injectors. Grounds and fuse links (including the main  positive one right of the battery that feed the ECU harness). Don't be confused by the color of wires Red and Black do not always relate to positive and negative on the harness. Think that was an issue for another poster recently. You need to check voltages AT the disconnected 36 pin connecter. This assume the fuel injectors are not the problem (gummed up) a noid light would be a test to see if they are getting pulses.

the only shot gun approach that you can consider is a check of all grounds and connectors (bullet and EV1 style on the sensors and injectors). these corrode and can give all kinds of problems, not easy to find using the typical voltage check due to the low currents of the test equipment (typical of DMM's). A  very corroded contact will not drop voltage when measured with a high impedance voltmeter, but in actual use when current loads are much higher the resistance cause by the corrosion can have a large voltage drop.

Again make sure the thermotime and the temp sensor wires have not been switched around they have the same connector ends (bullet) and can be reverse causing all kinds of issues. You can tell for sure by simply tracing from the theromtime (large on the thermostat) wire harness, trace to where it connects back to the cold start valve. its in a shared harness with the temp sensor but you can tell which is which by careful observation. the Temp sensor is the smaller of the two things that screw into the from of thermostat. It to is frequently a problem, but its easy to test and is part of the 36 pin check out items in the FSM. Its a simple thermistor type device so the test will include comparing the water temp (or ambient if the car is cold) to a chart where there resistance changes with temp. When these go you tend to have rough running due to too rich as they typically drift up in resistance. However again this is just conjecture as to what could be wrong, test things before replacing. And don't overlook the possibility of corrosion or wiring errors (which is why I suggest the shot gun approach on the cleaning of connections).

One last thing to note, the wire harness is well past its expected life span, with that in mind exercise care when connecting/disconnecting/flexing etc... its easy to break wires, just adding to user caused problems that then need to be sorted.  If you see a LOT of green corrosion on the pins of the connectors its likely that you will need to do some extensive surgery to excise the problem wires as that green has a way of working up a copper wire. Just keep this in mind when looking over stuff.

 

 

 

 

 

 

[Eric280zx]

9 hours ago, Dave WM said:

do what JSM said, disconnect the CSV hose and cap it for now. should not be firing at all unless its cold where you are. At lest you will stop flooding the crankcase with gas (I would drain the oil and refill again until you figure this out, no reason to destroy the bearings in case is starts from gas thinned oil). you need to get to a point where NO fuel is spraying with the key in start and the starter solenoid disconnected. You should just see the pressure jump to 36 psi, then release the key from start and it should stay there at least for several minutes. How well it holds pressure will tell you if you are leaking fuel OR the fuel pump check valve could be bad. Regardless, get that working before moving on. Its best to resolve one system at a time rather than jumping from one magic bullet to another. Don't start replacing parts unless you know they are bad, doing so only adds more variables that can cause it to be harder to figure out what is wrong.

Next you need to review the FSM and sort out the EFI injectors. Grounds and fuse links (including the main  positive one right of the battery that feed the ECU harness). Don't be confused by the color of wires Red and Black do not always relate to positive and negative on the harness. Think that was an issue for another poster recently. You need to check voltages AT the disconnected 36 pin connecter. This assume the fuel injectors are not the problem (gummed up) a noid light would be a test to see if they are getting pulses.

the only shot gun approach that you can consider is a check of all grounds and connectors (bullet and EV1 style on the sensors and injectors). these corrode and can give all kinds of problems, not easy to find using the typical voltage check due to the low currents of the test equipment (typical of DMM's). A  very corroded contact will not drop voltage when measured with a high impedance voltmeter, but in actual use when current loads are much higher the resistance cause by the corrosion can have a large voltage drop.

Again make sure the thermotime and the temp sensor wires have not been switched around they have the same connector ends (bullet) and can be reverse causing all kinds of issues. You can tell for sure by simply tracing from the theromtime (large on the thermostat) wire harness, trace to where it connects back to the cold start valve. its in a shared harness with the temp sensor but you can tell which is which by careful observation. the Temp sensor is the smaller of the two things that screw into the from of thermostat. It to is frequently a problem, but its easy to test and is part of the 36 pin check out items in the FSM. Its a simple thermistor type device so the test will include comparing the water temp (or ambient if the car is cold) to a chart where there resistance changes with temp. When these go you tend to have rough running due to too rich as they typically drift up in resistance. However again this is just conjecture as to what could be wrong, test things before replacing. And don't overlook the possibility of corrosion or wiring errors (which is why I suggest the shot gun approach on the cleaning of connections).

One last thing to note, the wire harness is well past its expected life span, with that in mind exercise care when connecting/disconnecting/flexing etc... its easy to break wires, just adding to user caused problems that then need to be sorted.  If you see a LOT of green corrosion on the pins of the connectors its likely that you will need to do some extensive surgery to excise the problem wires as that green has a way of working up a copper wire. Just keep this in mind when looking over stuff.

 

 

 

 

 

 

Very detailed information, thank! So right now I checked fuel pressure and at prime it's at 40psi and starting is 38psi but when I release the key the psi slowly go back down and doesn't stay like Dave said it should. No fuel is spraying, all seven injections didn't drip, so up next is the fuel pump check valve that could be bad. Where is it located, I'm going to replace this part and see if it maintains the 36psi and not just drop