Jump to content

IGNORED

1977 280z no power on fuel pump


240zadmire

Recommended Posts

Hi

 

car is early 1977 280z

I recently put back the car after take it out for painting interior, engine bay.

When turn ignition to on I hear no sound on the fuel pump.

what I did:

- connect direct power from battery to the 2 wire on the passenger side and hear fuel pump.  Which means pump is good.  Check continuity from the wire to the relay connector is good.

- check the continuity base on the fuel injector bible on pin 20 against ground, no continuity.

- ignition coil and spark plugs has electrical.

 

funny thing is that both the pins of the cold start valve are positive.  I connect positive pin from the voltmeter to battery and the negative to any pin has 12 volts.

 

what did I do wrong? Some wire definitely messup

 

thanks

 

 

 

 

 

Link to comment
Share on other sites

There are three areas you can check. The FSM has the diagnostic checks for the fuel pump circuit. Involves the afm, oil pressure switch and alternator. Chances are when the engine bay was refurbished there is an open circuit at one of those areas. The FSM will lead you through the diagnostics. 

Link to comment
Share on other sites

don't worry about the cold start. Its powered only during "start" and pretty sure its activated by grounding (like the other injectors). You should get a FSM and read the entire fuel injection chapter, read it again... its very through with lots of good info, but will take some time to get thru it.

Link to comment
Share on other sites

5 hours ago, 240zadmire said:

 

 

"funny thing is that both the pins of the cold start valve are positive.  I connect positive pin from the voltmeter to battery and the negative to any pin has 12 volts."

 

 

 

 

 

 

 

 

 

The above does not sound right at all as far as how your are testing things. You would want to confirm voltage is getting to the CSV by connecting a positive meter lead to the CSV harness and the neg lead to the chassis ground. Nothing to the battery positive. Next you would turn the key to start, look to see if 12 is there only during start. If not try the other side of the harness and test again. This is with the injector unplugged from the harness. Also consider the CSV does not generally activate unless its under 70f or colder. It frequently fails to fire due to the thermotime switch going open from corrosion. Lastly a properly working system will only fire on "start" for a limited number of seconds before it disables itself to avoid flooding (thermo/time).

Link to comment
Share on other sites

9 hours ago, 240zadmire said:

When turn ignition to on I hear no sound on the fuel pump.

As everyone is saying, this is correct.  The pump does not get power when the key is on. 

Here's the pump test from the FSM.

image.png

Link to comment
Share on other sites

@Zed Head and all,

 

Just before I left for work,  I did the below:

I move the AFM flap all the way to the left and check pin 20.  Set voltmeter to continuity test and got something like 572.  Not sure what that mean.

Look at the circuit diagrams, seem like CSV and Thermotimer are connected in parallel.  I traced the circuit between the CSV and Thermotimer, one pin on CSV and the other on thermotimer and seem to have continuity.  repeat the same steps for the other pin and also got the continuity.

 

I did replace all the fuel injection connectors as they wore out.  I was very careful about which pin for which side.  I also did replace the connector for the thermotimer and the coolant temperature.

I did not replace the CSV and Auxiliary connectors as I ran out of connector.  I was very careful about the which wire goes to which.  Hopefully I didn't screw up somewhere by connect positive to negative wires. 

I will check again when I get back home.

Thank you all for the help.

will keep everyone posted.

 

regards

 

Link to comment
Share on other sites

@Dave WM

 

History of the car was that it sat for 10+ years.  Was running very before it sat there, previous owner stated.  Bought and able to get it working and confirmed still very rough on idle.  Replace all vacuum hoses and clean up all electric connectors where possible.  Seem to fix it.  However, after a drive when put back in neutral at stop light, high rpm stayed for at least 20 seconds before idle normal. 
 

long story short, few rust here and there, paint faded... pull the engine to fix the rust.... and we all know, one thing led to another, couple of years gone by, all rust spots fixed and paint inside out.... put the car back to where it rightfully... and now I’m trouble shooting it.

 

must be some ground/wire broken somewhere.  I don’t know. 
 

regards

Link to comment
Share on other sites

you are going to need to systematically address each issue. start with getting the pump running, for this the FSM would be best.

But to jump the gun, you need to get a fuel pressure gauge installed, then pull the starter solenoid wire, turn the key to start, while in start the pump should run. if it does note the fuel pressure, should be around 36 psi. This will at least test to see if the pump can run in the most basic mode (start) and that it can produce the required pressure.

Next up will be to confirm a spark, for this you will need to replace the solenoid wire, pull the center coil wire, get it close to the chassis ground and crank the engine, this will confirm a spark.

Then you will need to confirm the plug firing order. reattach the coil wire, and see if the engine can run on some starting fluid sprayed into the TB, if it runs at all then you will need to see what the pump needs to run, some need AFM input from a micro switch, others need oil pressure, and some may need input from the alternator. All this is so the pump will NOT run if the key is in "ON" but the engine is not actually running, its a safety thing to keep gas from pumping into the engine bay, possibly fueling an engine fire. Its not something you want to bypass.

So its going to be up to you to determine what system your setup uses. It may have be altered at some point in the life of the car. Typically you could just look at the AFM and see if it has 5 or 7 leads. If 7 then its AFM controlled, if 5 then the AFM is not controlling it so something else is (does the oil sending unit have to connections or just one).

Anyway once the fuel pump is behaving as it should then you need to start looking at fuel control, that would be the ECU and injectors. What you don't want to do is load up the parts cannon and fire, all that does is introduce possible errors in the replacement of parts. there is a process that needs to be followed to sort this out.

Link to comment
Share on other sites

Hi all,

apologies if I miss state the current situation.

 

- the car crank up

- there sparks on each spark plug

- direct wire connect to fuel pump, the pump spin

- fusible links have continuity 

- starter works hence sparks on spark plugs

- turn the key to on, a noise coming out from AFM

 

connect voltmeter to fuel pump while turning the key to start got zero volt.  That’s why I start from to trouble shoot why there is no power to the fuel pump.

i will keep digging from the manual to find info.  
 

I’ll be honest, tracing wire diagrams and the symbols like relay is pretty tough for me.  The answer is all there.  It just doesn’t make much sense to me is all.  I’ll keep looking but if you have more info, please help.

@Zed Head I’m not offended that easy.  If I don’t know, I don’t know.  Remember you help me the other day with the brake could not hold pressure!? It’s only easy if someone point it out what you did wrong.  It would take me days if not weeks to figure it out.  But once you explained, made perfect sense and I thank you for that.  I learned something.

 

regards

 

 

 

  • Like 1
Link to comment
Share on other sites

Another finding, doesn’t look like oil pressure sending unit has continuity.  I took it off the engine and one pin on a terminal and the other on the body and got 115 number.  Usually if there is a continuity, i get a continuous beep.  Check the resistant and I got 89 ohms.

 

could that be it?

 

regards

 

Link to comment
Share on other sites

6 hours ago, 240zadmire said:

Another finding, doesn’t look like oil pressure sending unit has continuity.  I took it off the engine and one pin on a terminal and the other on the body and got 115 number.  Usually if there is a continuity, i get a continuous beep.  Check the resistant and I got 89 ohms.

 

could that be it?

 

regards

 

the readings you are getting is resistance in ohms. Continuity is a term used in the FSM that maybe confusing, it means there is a low resistance complete circuit. beeping is something the meter will do if the resistance is low enough. the resistance of the oil sending unit varies based on pressure IIRC something between 100 ohms (no pressure) and 30 ohms (high pressure). That is for the oil pressure gauge, and is not the issue for the pump. Since you have a 7 pin AFM the 1st thing to check would be is the micro switch working. Next suspect would be the ignition relay.

if those check out the ignition switch could be bad, it sees a lot of use over the life of the car.

Link to comment
Share on other sites

6 hours ago, 240zadmire said:

Another finding, doesn’t look like oil pressure sending unit has continuity.  I took it off the engine and one pin on a terminal and the other on the body and got 115 number.  Usually if there is a continuity, i get a continuous beep.  Check the resistant and I got 89 ohms.

 

could that be it?

 

regards

 

Absolutely...NOT. As I said in my first response, you don't have an oil pressure switch in your car. The sending unit only supplies a signal to the gauge. The sending unit should have resistance with the engine off.

EFI relay and fuel pump operation in more detail:

  1. The W/B wire (from the Ignition Relay) brings 12VDC to the EFI relay coil 1 on pin 71. The W/B wire has 12VDC when the key is in the ON position.
  2. At start, the B/Y wire from the starter brings 12VDC to the EFI relay coil 2 on pin 76. (and it is supplying 12VDC to the cold start valve via pin 47) It is also sending voltage to the ECU from pin 20.
  3. Pin 72 is the ground signal for both coils. It is grounded through the ECU.
  4. At start, the EFI relay coil 2 closes the contact between pins 73 and 74 when the ECU grounds pin 72. Pin 73 gets 12VDC from the W/R wire that comes off one of the fusible links. Pin 74 is the G/L wire going out to the gas tank.
  5. When pin 72 is grounded (Key in ON), 12VDC from the W/R wire at pin 70 (from the EFI fusible link) is connected to pins 39, 10, and 43.
  6. When the AFM flap is open, voltage goes from pin 39 to pin 36. This allows pin 36 to energize the EFI relay coil 2. The contact closes between pins 73 and 74, sending voltage to the fuel pump.

Since you said you aren't getting voltage to the fuel pump (and you have a good ground at the fuel pump), I am thinking the ECU is not providing the ground for the EFI relay like it is designed to do. Another alternative is that you have a bad/missing fusible link for the EFI. This fusible link is sometimes overlooked because it is not mounted on a nice block like the other four. (See the last response in this thread: https://www.zcar.com/threads/where-is-the-darn-fusible-link-for-the-fuel-injection.278457/

With everything connected, make sure you have 12VDC to ground at pin 70 on the EFI relay.

Make sure you have clean connections between the ECU and wiring harness. Also make sure the ECU is grounded where it needs to be grounded.

You will likely need to go through the ECU diagnostics as described in the EF section of the 77 FSM if you have 12VDC to ground at pin 70.

If you haven't done so already, download a copy of the FSM. You can find it here: https://www.classiczcars.com/files/category/13-280z/

Link to comment
Share on other sites

Hi all,

 

The micro switch on the steering column on the signal side? Is it the one where my finger point to it or the plastic where 3 wires coming in/out? And the fusible link for the ignition at the positive terminal?

 Please see the attach photos

also, I haven’t connect any light to the car yet such as signal, beam, rear.  I did however replace all the small bulbs inside the dashboard since I took it out and might as well replace them all just in case any burn out later.  I’ve replaced them all with LED.  Few tiny wedge bulbs I left a lone as I couldn’t find suitable ones.

 

since I don’t have signal lights connected, turning signal only get steady left/right.  I think it is normal?!

i will cleanup the micro switch later

 

3FC0FA4D-29D3-4EA8-B632-4557A0132836.jpeg

65411D66-AA62-4132-B107-4EB2DFD3B4AF.jpeg

Link to comment
Share on other sites

i do have the FSM and the schematic from https://www.atlanticz.ca/zclub/techtips/wiringdiagrams/F77ZCAR-WIRING1.pdf.

I've been tracing wires and trying to make sense out of it.  Below are what I replaced:

- engine piston rings

- valve seals

- head gasket

- timing chain

- valve springs 

- fuel injectors' harness

- spark plugs

- spark wires

- ignition coil

- distributor cap

- vacuum hoses

- thermostat

- radiator hoses

- radiator fan clutch

- dashboard bulbs.

 

part of the tear down/rebuild, above those were replaced.  I hope I didn't screw up too deep that there is no point of return.  The plus side to this madness was that the suggestion to squirt starting fluid and see if engine work, and it did fire up right away.  I was really, really relieve.  I hope now it boil down to electrical issue somewhere that missing connection/bad grounding ...

regards,

Link to comment
Share on other sites

dumb question.

will it cause more problems if I hot wire the fuel pump so that I can start the car?  This will by pass all the safety of the intended relays/sensors.... of course, for the troubleshooting part to make sure continuous fuel and pressure will keep the car running.

what do you think?

 

regards

 

Link to comment
Share on other sites

12 hours ago, 240zadmire said:

put a few squirt of engine starting fluid, start the engine and it fires up right away.  Please see the video.  As soon as the fume is done, engine stops as expected.  

I would focus on the fuel pump relay.  You have a lot of other stuff going on at the same time.  Very distracting.

Break the circuit down in to parts.  Confirm power to the fuel pump relay.  Confirm power on the circuit that is supposed to trigger the relay.  If the trigger circuit doesn't energize the relay then you know where to focus.  77 has the combined relay.

The FSM procedure is very complex and overdone I think.  Like an engineer wrote it!  I would just identify the couple of important pins in the plug and measure voltage there.

Link to comment
Share on other sites

I always find it best to fix the problem rather than work around it just to see it run. You know it works based on the starter fluid, so mechanically its sound and the spark is working. You need to dig in with the multimeter and resolve the problem.

Link to comment
Share on other sites

1 minute ago, 240zadmire said:

dumb question.

will it cause more problems if I hot wire the fuel pump so that I can start the car?  This will by pass all the safety of the intended relays/sensors.... of course, for the troubleshooting part to make sure continuous fuel and pressure will keep the car running.

what do you think?

 

regards

 

It's very common to hot wire the pump for troubleshooting.  Wire it to a circuit that is powered by the key or have a switch handy though so that you can turn it off quickly.

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
×
×
  • Create New...

Important Information

By using this site, you agree to our Privacy Policy and Guidelines. We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.