# Cranks No Start, Need Help or Guidance



## Mo_Heato (Apr 14, 2020)

Hi, so basically after I bought my z, it ran pretty nice after I replaced the battery cables, brake lines, and clutch parts. Then, my dumbass got excited and hooked the battery up backwards while getting ready to drive it.

So I replaced the main battery fuse, and car wouldn’t get fuel to the injectors. I ended up replacing the fuel pump, injectors, fuel filter, & then it got Good fuel pressure to the injectors, I’ve also replaced spark plugs/wires, ignition coil, CAS, did a full timing belt service, replaced my fuses, tested the relays by the battery, chts sensor/harness, alternator, and some gaskets.

I have not put a new battery in which I’m thinking I should and I opened the ecu and it doesn’t look fried, but I don’t know where to go from here if anyone has a process I can go through or any ideas it would be amazing.


----------



## rogoman (Dec 16, 2004)

After you did a massive replacement of parts, I assume that it still will not start? Before we can help you, we need to know the model of the Z car, (like a 240, 300,370, etc), the year, turbo or non-turbo, transmission type.

One of the first things to do is perform an ECU code readout with a portable scan tool to see if any fault codes are set. The tool can be purchased at most auto parts stores or online at Amazon.com. Post the actual codes here on the forum so that we may be able to help you further. If there is one or more fault codes set, they can help point to the malfunction. If you have a copy of the FSM for your vehicle, the code readout procedure is described there along with a listing of codes. You can download a copy of the FSM from these web sites:
Nissan Service Repair Manuals
Owner's Manuals. 

The section EC.PDF is the one you need to read.

At this point you'll have to determine if there's an ignition or fuel delivery problem.


----------



## Mo_Heato (Apr 14, 2020)

Okay, it’s a 1984 Nissan 300zx NonTurbo. I have one but I can’t hook up a scanner to it, I did read blink codes though and got a code 12 for a bad MAF.


----------



## rogoman (Dec 16, 2004)

Mo_Heato said:


> Okay, it’s a 1984 Nissan 300zx NonTurbo. I have one but I can’t hook up a scanner to it, I did read blink codes though and got a code 12 for a bad MAF.


Are you able to start the car up at this point? If the MAF is bad, you should still be able to start the car up. However it'll run in fail-safe mode where the maximum RPM would be around 2500.


----------



## Mo_Heato (Apr 14, 2020)

I still can’t start it up, before I sprayed starter fluid in and it would start and once it stayed on for a good 20 mins and revved up fine, idk why it won’t start now even with spray. I’m sure my spray damaged the MAF


----------



## rogoman (Dec 16, 2004)

Mo_Heato said:


> I still can’t start it up, before I sprayed starter fluid in and it would start and once it stayed on for a good 20 mins and revved up fine, idk why it won’t start now even with spray. I’m sure my spray damaged the MAF


At this point you'll have to determine if there's an ignition or fuel delivery problem:

* Testing fuel delivery:
An easy way to test the fuel pump and filter is to disconnect the fuel feed hose from the fuel rail and connect it to a long length of spare hose with the other end draped over the fender going into a catch can placed on the ground. Now turn the ignition key to the run position but *DO NOT START THE ENGINE*. You should see fuel going into the can at a good rate for several seconds. 

Tee-in a temporary fuel pressure gauge between the fuel feed hose and the fuel rail. Turn the ignition key to the run position but *DO NOT TRY TO START THE ENGINE*. The fuel pressure reading should be around 37psi which would be a static reading.

The fuel injectors may not be firing. This can be tested with a "noid" light probe for each injector harness connector; the probe kit can be purchased at most auto parts stores or online at Amazon.com. If you find that the "noid" light is not flashing for all the injectors, this could be due to a bad crank angle sensor or a bad ECU. The crank angle sensor is located inside the ignition distributor.

* Testing ignition:
Pull several spark plug wires test; use a spare spark plug in the plug wire to test; ground the plug base with a jumper wire to the engine block; see if you're getting a spark while trying to start the engine. If there's no spark from any spark plug, then the ignition coil, power transistor, ECU or the crank angle sensor could be bad.

* The cam timing may be incorrect:
Check for a broken chain guide. If the engine uses a timing belt, see if it's broken or it may be cracked and has skipped some teeth.

* There may be a major intake system vacuum leak. Check the intake manifold nuts to make sure they are tight. The gasket may have failed. Also check the intake plenum bellows at the throttle valve and at the MAF for cracks or loose clamps.


----------



## Mo_Heato (Apr 14, 2020)

Ok I just changed the intake gaskets, and tested for spark and did a timing service, so I’ll do the fuel tests and noid light and check for any air leaks


----------



## Mo_Heato (Apr 14, 2020)

Also some of my vacuum lines are broken around the engine bay but I don’t know what all of them go too, I did replace the fuel vacuum lines and more but do you have some kind of diagram for that? I can’t find one in my FSM


----------



## rogoman (Dec 16, 2004)

Mo_Heato said:


> Also some of my vacuum lines are broken around the engine bay but I don’t know what all of them go too, I did replace the fuel vacuum lines and more but do you have some kind of diagram for that? I can’t find one in my FSM


Try here: vacuum lines 1984 300zx - Google Search


----------

