Power to injectors

[Zed Head]

On 4/14/2017 at 9:58 AM, DC871F said:

82 NA 280ZX.

I have fuel, spark, but no power to fuel injectors. Crank angle sensor seems intact(wiring). Car has been sitting many years, has fresh fuel, no blockage in fuel rails.

I would try starting fluid, with a squirt of oil in each cylinder, before going too far, just to be sure it's an injection problem.  If you didn't flush the lines to the injectors you might be squirting old dead fuel or water in to the cylinders.  The injectors also tend to get stuck closed if the fuel in them dries out.  I've freed them up by tapping with a screwdriver.  There are many other possibilities for not firing or not injecting.  You have to work your way through them.  Using starting fluid is a good way to test many things at once.  Timing, spark, compression, etc.  

A friend and I spent hours trying to get an old 1963 Bonneville to start that had only been sitting one year.  A farmer cruised by on his tractor and told us to squirt some oil in the cylinders.  We did and it fired right up.  The rings were dry and it just wasn't compressing the fuel-air mix.

I've also had an engine that had spark but it was weak.  It would only start with starting fluid until I changed the ignition module.  Your ZX module could have bad grounding and produce a weak visible spark, not strong enough to kick off old fuel in dead dry cylinders.  Could be a combination of weaknesses.

Edited April 15, 2017 by Zed Head
Spelling and spaces

[DC871F]

2 minutes ago, Zed Head said:

I would try starting fluid, with a squirt of oil in each cylinder, before going too far, just to be sure it's an injection problem.  If you didn't flush the lines to the injectors you might be squirting old dead fuel or water in to the cylinders.  The injectors also tend to get stuck closed if the fuel in them dries out.  I've freed them up by tapping with a screwdriver.  There are many other possibilities for not firing or not injecting.  You have to work your way through them.  Using starting fluid is a good way to test many things at once.  Timing, spark, compression, etc.  

A friend and I spent hours trying to get an old 1963 Bonneville to start that ha donly been sitting one year.  A farmer cruised by on his tractor and told us to squirt som eoil in the cylinders.  We did and it fired right up.  The rings were dry and it just wasn't compressing the fuel-air mix.

I've also had an engine that had spark but it was weal.  It would only start with starting fluid until I changed the ignition module.  Your ZX module could have bad grounding and produce a weak visible spark, not strong enough to kick off old fuel in dead dry cylinders.  Could be a combination of weaknesses.

I removed the fuel rail return line and got fresh gas in the rail, but in the back of my mind I thought about the injectors being clogged. Honestly I should have stopped after not getting it to fire off after new fuel and new pump and just removed the rail and injectors to clean and inspect.

Just did the EFI relay check and its good. I installed new coil just for troubleshooting and no change. Ill try the oil and start fluid and if no change, ill put the meter down and pick up the wrenches and remove the rail and injectors to see condition.

Thanks

[Zed Head]

Another test for the injection system is to connect a lead to the coil's negative post.  Let the other end hang free, turn the key On then tap the free end of the lead to ground to create a spark.  Every third tap should cause all six injectors to click.  That test works all of the parts, including the ECU.  It provides a stronger spark though because the starter motor is not engaged.

If you sit down and think things through and collect all of these various suggestions, you can come up with a systematic plan to test parts, in addition to the factory tests.  You're talking about taking the injectors out but you haven't test their functioning yet.  You can also ground each injector at the ECU connector, with the key On, mimicking the ECU's function.  Then you'll know if they're stuck.

Lots of little tricks out here.

[Chickenman]

Go to Napa, Autozone or even WalMart. Pick yourself up a Noid light or two. You can buy whole kits for under $20 on E-Bay. I buy universal ones at Princess Auto for $1.99 each.  Plug into the end of the injector terminal and they will tell flash with injector pulse. Makes it easy for testing for stuck or dead injectors. 

 

Picture below is what I pay $1.99 for at Princess Auto:

http://www.ebay.com/itm/WILMAR-BOSCH-PFI-NOID-LIGHT-W85102-/282404897015?hash=item41c0a4c0f7:g:r48AAOSwax5Y0XZb

 

 

[DC871F]

13 hours ago, Chickenman said:

Go to Napa, Autozone or even WalMart. Pick yourself up a Noid light or two. You can buy whole kits for under $20 on E-Bay. I buy universal ones at Princess Auto for $1.99 each.  Plug into the end of the injector terminal and they will tell flash with injector pulse. Makes it easy for testing for stuck or dead injectors. 

 

Picture below is what I pay $1.99 for at Princess Auto:

http://www.ebay.com/itm/WILMAR-BOSCH-PFI-NOID-LIGHT-W85102-/282404897015?hash=item41c0a4c0f7:g:r48AAOSwax5Y0XZb

 

 

I tried that with a test light and nothing happened, which started this Easter egg hunt. (No pun intended)

[DC871F]

16 hours ago, Zed Head said:

Another test for the injection system is to connect a lead to the coil's negative post.  Let the other end hang free, turn the key On then tap the free end of the lead to ground to create a spark.  Every third tap should cause all six injectors to click.  That test works all of the parts, including the ECU.  It provides a stronger spark though because the starter motor is not engaged.

If you sit down and think things through and collect all of these various suggestions, you can come up with a systematic plan to test parts, in addition to the factory tests.  You're talking about taking the injectors out but you haven't test their functioning yet.  You can also ground each injector at the ECU connector, with the key On, mimicking the ECU's function.  Then you'll know if they're stuck.

Lots of little tricks out here.

I will go try this, thank you.

[DC871F]

19 hours ago, Zed Head said:

Another test for the injection system is to connect a lead to the coil's negative post.  Let the other end hang free, turn the key On then tap the free end of the lead to ground to create a spark.  Every third tap should cause all six injectors to click.  That test works all of the parts, including the ECU.  It provides a stronger spark though because the starter motor is not engaged.

Why does that make the injectors fire?

[Zed Head]

It's described in the FSM.  The ECU uses spark counting to know the crankshaft has turned.  It's a revolution sensor but not an angle sensor.  As noted earlier, your car doesn't have a CAS if it's NA.

[Chickenman]

6 hours ago, DC871F said:

I tried that with a test light and nothing happened, which started this Easter egg hunt. (No pun intended)

Not sure how you tested, but a test test light can sometimes fool you. Injectors always have a constant 12 volts. If you probe the hot side of injector harness, test light should light up with engine cranking over. However, that does not tell you if you are getting an injector pulse because it is the ground side that is switched on and off. NOID lights are a cheap and effective way of testing for injector pulse. NOID lights just test up to the harness end. You can still have a physically dead or stuck injector. 

Obviously if you probe the hot side of the injector terminal, crank the engine over and test light does not light up... then you know you are not getting any power at all to the injector harness and you need to find out why. 

ZH's method will also work You could use ZH's method to test each injector 1 at a time to make sure they all work. 6 injectors clicking at same time can sometimes confuse you, so I like to connect and test them one at a time in the relevant terminals.   

Edited April 16, 2017 by Chickenman

[DC871F]

8 hours ago, Zed Head said:

It's described in the FSM.  The ECU uses spark counting to know the crankshaft has turned.  It's a revolution sensor but not an angle sensor.  As noted earlier, your car doesn't have a CAS if it's NA.

I meant to say 

 

8 hours ago, Zed Head said:

It's described in the FSM.  The ECU uses spark counting to know the crankshaft has turned.  It's a revolution sensor but not an angle sensor.  As noted earlier, your car doesn't have a CAS if it's NA.

Meant to say to "Cold start valve". Ill give this try tomorrow, I really appreciate your help.

[DC871F]

4 hours ago, Chickenman said:

Not sure how you tested, but a test test light can sometimes fool you. Injectors always have a constant 12 volts. If you probe the hot side of injector harness, test light should light up with engine cranking over. However, that does not tell you if you are getting an injector pulse because it is the ground side that is switched on and off. NOID lights are a cheap and effective way of testing for injector pulse. NOID lights just test up to the harness end. You can still have a physically dead or stuck injector. 

Obviously if you probe the hot side of the injector terminal, crank the engine over and test light does not light up... then you know you are not getting any power at all to the injector harness and you need to find out why. 

ZH's method will also work You could use ZH's method to test each injector 1 at a time to make sure they all work. 6 injectors clicking at same time can sometimes confuse you, so I like to connect and test them one at a time in the relevant terminals.   

When I just was using the Haynes manual, It had a picture of a simple test light that was made up to plug into each injector plug. It said it was supposed to pulse above 80 RPM. So I made a similar test light and plug. I inserted it into the injector plug with nothing happening (no pulsing). I plug it on the hot side of the injector plug and then to ground and it shows power.

If i'm not getting the pulse, does that mean the ECU is bad? I plan to do ZH's recommended test tomorrow from the coil to see if I can get the injectors to fire.

[Chickenman]

Quote

If i'm not getting the pulse, does that mean the ECU is bad? I plan to do ZH's recommended test tomorrow from the coil to see if I can get the injectors to fire.

Not necessarily....  ( ECU bad ). Keep testing and eliminating issues one at a time. Let us know what ZH's method shows up.