1990 300zx NA--Crank, No Start Condition. Please Help!!!

[EzioWolf]

I just got this car and it hasn't run in about a year. I have a new battery and the starter are reading fine. The car turns over with out any problems but it just won't start.

The fuel pump is acting slightly different than others situations. When I have the car in the key off position the fuel pump does nothing. When the car is in the key on position (with out turning over the car) the pump turns on but it will never shut off. When I turn the car over the pump works harder and still will not shut off until I turn the ignition back to the key off position. Also I do get a fuel smell after trying to start the car.

I have replaced the fuel pump relay, and I believe I have cleaned and checked all of my grounds. All of the wires and wiring harnesses seem to be intact. Also I removed the hose after the fuel filter to see if I was getting fuel, and sure enough the key wasn't even on for a millisecond and fuel was shooting out like a waterfall.

I have been researching on this for about two weeks now and have had no success. The closest thing I had seen to my situation is that someone diagnosed it as a bad Ignition Coil Relay.

Can someone please help me out with this? I need to get this car on the road so I can get rid of this altima with a ridiculous car payment.

[Rogue One]

Just a quick heads up. I deleted your other thread. This helps prevent any confusion and keeps your problem in focus.

[Taleek]

Well basic things to check, suck, squeeze, bang, blow. In other words make sure you do actually have fuel getting to the cylinders, also, do a compression test to ensure you're getting correct compression, check your ignition, make sure you're actually getting a spark. And compression test will cover the blow part. That's where I would start at least, I can speculate on your possible fuel pump problem, but its gonna be something among those of why your engines not running.

[RubyRed300ZX]

You need spark, air and fuel. With spark at the correct time. I know that's all obvious. However, just a reminder. Also, flow and pressure are two different things. You may have flow; but, you may not have enough pressure. You need at least 20psi to get it to start. Should have 43.6 psi I believe. But, you need at least 20 to get it to start.

[EzioWolf]

Just an update, I do have sufficient spark on all six coils. I have done a compression test and the compression is fine. Also it seems like it's getting enough air cause my buddy held his hand up to the intake and said it was sucking really good. I will do a fuel pressure test today to see what I come up with.

[EzioWolf]

Also would a missing MAF Sensor keep it from starting? I looked it up and a couple place said it shouldn't keep it from starting, but it would restrict RPM at 2400 at max.

[Taleek]

Right, "a missing or malfunctioning MAF would make the ECU refer to the TPS for information on driving condition. ECU will limit engine speed to less than 2000-3000 RPM depending on model."

So basically no, a missing MAF sensor shouldn't prevent the engine from starting, it will however limit the RPMs.

Have you finished the fuel pressure test?

[DCaff300ZX]

Two things- first, when you pulled the fuel line and it was shooting fuel that is because the system is pressurized to 43.6 psi as mentioned, and you need to relieve that pressure before removing the hose. The second thing also mentioned is that as you will be testing for, there is a required amount of pressure for the injectors, which is most likely where your issue is. Either the injector is dead and not functional, or more likely is stuck "on" and allowing too much fuel to push past into the cylinder and also therefore reducing fuel pressure for the rest of the injectors.
Best test for you now is to ohm the injectors and each should be at 15.2 ohms or close to that (can't recall the EXACT 15.whatever ohms) and if any other reading, the injector is bad and needs replacement.
I also would get a functional MAF involved for peace of mind, and because no MAF is also a large vacuum leak without MAF signal. Trying to jury-rig during a testing procedure is never a good way to go- better off to be as close to 100% as possible to avoid confusion and any other possibility.

[EzioWolf]

Unfortunately I have been unable to fulfill the fuel pressure test so far. I haven't had time to go get the gauge for it. After I do the fuel pressure test and the tests on the injectors I will give you guys another update. I will get a hold of a MAF very soon as well. I tried bypassing the Fuel Pump Control Unit to see if it was causing the fuel pump to act weird, and I had no luck there. I'm getting a feeling that it may be the ECU acting up.

[EzioWolf]

Ok guys I did the fuel pressure test and I'm reading 43.6 psi with the key on. After I get it up to that pressure and I turn the key off it goes down to about 15psi and then very slowly drops in psi from there.

[Taleek]

Sounding like Dcaff is going the right direction maybe. Have you tried the injector OHM test to ensure they are good? Do you know if the engine was taken apart, or even the timing belt was removed? If you're getting the proper pressure and spark then whats left is the timing. Assuming of course the fuel injectors and spark plugs are ok.

[DCaff300ZX]

Thanks Taleek...and yes, I'd head for the injectors and connectors next, ohming the injectors looking for 15.2 ohms rsistance IIRC (PLEASE check that!) with anything out of spec being your problem. Check the connectors as well for green corrosion and clean completely using electrical grease when reassembling, this can sometimes be the problem or at least part of it.
Let us know what you find and get for readings.

[EzioWolf]

Ok guys real huge update. SHE STARTS NOW!!! Fist time she has started under my ownership! I was told, by my friends father which is a master tech in Japanese vehicles, if the car would start with starting fuel to keep the car running however I could so I can force fuel through the system. So after the car started I kept RPM at 3k for a few minutes and then slowly lowered the RPM until I let off the throttle completely.

After that, the car did start by itself, but the idle was at 300 RPM. With it idling at 300 RPM, if I stepped on the throttle it would take about 6-10 seconds for it to reach 1k RPM, and then after that the throttle response would progress like normal.

Do you guys think I should still check the injectors? Also I will be replacing all spark plugs anyways, so I will let you guys know If that makes any changes.

Also how do I pull the connectors off of the injectors? Is there a way to pull them off without removing the intake? please let me know. Thanks!

[DCaff300ZX]

Definitely check the injectors.
The connectors come off after you remove the little wire clips, although I've also heard others say they can work them off without removal of the clip but I've never been able to do that myself. They break easily also as they are old and brittle. Replace the clip before replacing, you then just push it back on (after cleaning) and it should snap in and stay seated. Use di-grease when replacing also, to inhibit corrosion and ensure a good contact.
I'd also be sure there is a new fuel filter and from the rpm you mention, perhaps test for fuel delivery issues such as poor fuel pump pressure, and bad fuel pressure regulator/dampener.

[EzioWolf]

Thx Dcaff! Ill get on it as soon as I can and give you an update!

[EzioWolf]

Alright So I did the test and injectors 1, 2, 4, and 6 are stuck closed. I will be getting 6 new injectors and a gesket kit for the upper intake plenum. Anything else I should get?

I also got a new MAF, new air filters, new fuel pressure regulator and damper, and a new fuel filter.

[maik3r]

I just had to do all this on mine and I would suggested checking all your vac, coolant and idle air hoses, namely the preformed ones. If they're dry-rotted like mine, it's best replace them while the plenum is off and if they've not been replaced they will like split and be unusable. Z1 one has the idle air set for relatively cheap, ~$40. Same for the coolant hose kit, price varies. Good Luck

[EzioWolf]

Thanks for the suggestion. I was debating on replacing those old hoses.