Ajf40

Hello,

I have been reading and doing extensive research on my Nissan 90 300zx. I bought it off of a customer for $300 but it had been sitting for 3 years. Here is the problem that I am having and what j have done so far:

Replaced cas (found broken plug connector on cas)

Before when I did the test with the cas there would be no injector tick and no spark (grounded on plenum while turning cas with key at on position) nothing at all

Replaced cas and now the radiator fan will spin randomly, which I have read the same with several others doing the test. So I don't think this is my problem

Removed ptu ohmed no problem found checked ground and continuity between ptu and ignition coils all check out and j am getting the 12 volts to coils between ground and between 2 wires in coil

The engine turns over and I know I am getting fuel to the injectors. When I remove gas cap after attempting start it is pressurized also removed line going from fuel filter and it has good pressure

So my fellow z owners what would most likely be the cause of no fire and no fuel? Checked codes and only code is 55 which I believe is normal. Why would it not know it is having a problem? I am thinking this might be ecu related since from my research only the cas and ecu are involved with the function of both the injectors and spark. My only concern is when I ohm the injectors and the coils I am getting a high reading in all of them....out of range I just have a hard time believing that every injector and every coil needs to be replaced any advice would be much appreciated

rogerz

try this before tearing your hair out and throwin new parts at it.

When trying to start without success you can easily inject enough unburned fuel to effectively flood the engine (using old carburetor terminology). this then prevents you from starting the engine normally. If you have checked everything and still no luck try this. disconnect a wire from the fuel pump so it won't pump (on a z31 pull the fuse). you need a fully charged good battery for this. hold the gas pedal to the floor and leave it there. Then give it a long crank. you may or may not get a few pops. Do it again. it may run for a few seconds. do it again. When you no longer get any action reactivate the fuel pump and try a normal start.

Ajf40

Made some progress tonight. Rented injector light signal test kit from autozone. All connectors testing good for signal from ecu so I ether have all bad injectors or a clogged fuel rail...... Hmm all injectors are ohming bad so I guess I have to start with replacing these.... As far as coil packs they at all testing around .9 but no spark on any of them so I am going to go with my gut and order 6 injectors and the ptu..... If anyone has any comment or opinions please chime In

rogerz

did you even try what I suggested? You can't really ohm out the injectors without a really good vom. the resistance of a very small coil is not much. I think you are overthinking the problem and missing the obvious. What is a injector light test? A Noid light is what you need you apparently don't know enough about how things work to seriously test any system. without getting a true gage reading of the fuel pressure other than it comes out when I take off the hose you don't know anything. What does taking off the gas cap have to to with fuel pressure to the fuel ring. Do you think they use an air compressor to pressurize the tank and drives fuel to the engine? Your biggest problem is not knowing enough about the car to ask intelligent questions.

Ajf40

So quick to be rude. I hope you are having a better day.
I appreciate your feedback and didn't mean to offend you.
I can't try what you said because I have no spark. I don't see how it is going to even pop at all without spark.

As far as my meter I have a field piece sc620 so I doubt that is the problem ( I am an hvac technician so I need to have a good meter)

And yes you are right is called a noid light test kit....a kit that tests the signal to your injectors.

As far the the fuel pressure you are right I don't have any idea of what the exact pressure is and maybe that is part of the problem.

However I did turn the cas by hand and i still can't hear any injectors click even after replacing it, they are ohming bad, and they are getting signal to fire but not putting any fuel into the cylinder.

I will get a fuel pressure gauge to test the pressure though thank you that is good advice, I assumed he pressure was good because when I took the outlet off the filter and turned the car over it came out pretty strong. I will check it out and post back. Working on this car is a fun thing for me, I haven't been under the hood since I was 18-21 rebuilding variable valve timing (vanos units) on bmws for a small company called drvanos so my apologies for being rusty, however these are completely different animals than what I am used to.

Ajf40

Replaced ptu car started was had to keep it gased to stay running. Fixed some vacuum leaks and adjusted throttle car idles on its own now. Glad I did the ptu before I ordered injectors :-) running z for $630, much much more work needed

The_Ikon

Glad you sorted it out!