Put engine back in car, it cranks but won't start?

Hey guys. I just put the engine back into my NB2 Miata after having it out for a month or two working on various things (oil pan seals, turbo fittings, motor mounts, etc), and just put the engine back in a week or two ago. I got all the fluids and everything else I need back on the car, and tried to just start it up today.

Well, it cranks pretty strong but will not fire. I did try to prime the fuel pump a few times by turning the ignition on and off, but it doesn't seem to be helping. I heard what I thought was fuel being sucked up, but I'm not well versed in what that sounds like.

I went over the car and checked all electrical connections, and they all seem to be there I'm also running a Megasquirt, which I put a kind of rough base tune on late last summer.

I'm just not sure where to look from here. Any tips on getting the car to fire up after putting the engine back in? It has a full tank of fuel, but of course when the engine was out, the fuel line was emptied of gas.

I have no idea if there is anything like this on a Mazda 1.8, but on some 80's Hondas, there is an electrical connection under the distributor that is really easy to miss, and you end up with the same "crank but no start" condition.  So, what I guess I'm saying, is my suggestion is to triple check all your connections.

I had the same issue on a JDM K24.
Loosen up a connection carefully on the fuel rail & see if you have pressurized fuel. 
Then listen or feel the injectors if they are clicking. 
Take your intake loose & spray some PB Blaster or parts cleaner in the intake. It fired when spraying in the pb blaster & fuel pressure, but the injectors weren't clicking. The injectors had dry old gas in them & could not actuate. Swapped in the set from the 230,000 mile motor & it fired right up.
 

Have you connected to the squirt and make sure everything is awake and talking correctly?

mdshaw- Thanks! I have a mechanic's stethoscope, so I will check and see if they're clicking. Do you mean loosening a fuel line on the rail?

GPZ11- I did connect to the Megasquirt and it was reading data, but I didn't dig too deep into the menus, just the dashboard.

So, I just went out to the car with my mechanic's stethoscope, and noticed before I even used it, that when turning the ignition to the "ON" position, I believe I can hear the injectors clicking. I will post a video below. However, during cranking, it doesn't seem like they are clicking. Could this be the issue? I also don't remember them being so loud.

https://youtube.com/shorts/ekYhnzBcnRI?feature=share

EDIT: Just pulled a fuel line and had a nice big splash of gasoline go everywhere...so now I know that the fuel pump is pumping fuel (along with having a mess to clean up).

Maybe get a FI niod light to see if they are firing?

https://www.google.com/search?client=firefox-b-1-d&q=fuel+injector+noid+light

It's almost impossible to keep a Miata from cranking. That circuit is about as complicated as a flashlight and completely independent of anything else. All it tells you is that the battery has some juice in it.

The fuel pump prime happens when the ECU powers up. So that doesn't tell us much either.

So you have to go through everything else. Fire up that MS and check all the inputs, especially those related to engine rotation. Too much air gap on the crank sensor, for example. Or (and this is a fun one) a crank trigger wheel that's installed backwards. Go back to what you touched when the motor was on the stand, then confirm that all connectors and grounds are installed on the engine. Most likely it's something simple like that.

Did you spray a little pb blaster in the intake? Just a quick way to see if you have spark. It will fire & rev a little.  Or hookup an inline spark checker light, or the ol screw driver close to ground spark check.

It's most likely the ECU doesn't know the engine is turning so it's not firing injectors or plugs. It will still prime, though, so wet plugs are inconclusive. You have an ECU that will talk to you, so talk to it and see what it's reporting during cranking. It's highly unlikely that something failed spontaneously, so it's something that isn't being told to do its job.

Fuel lines reversed? 

Ask me how I know.

I'd check the crank sensor gap and connector.  Make sure the connector is clean and fully seated.  And what Keith said.  See what the Megasquirt thinks is missing.

wheelsmithy (Joe-with-an-L) (Forum Supporter) said:

Fuel lines reversed? 

Ask me how I know.

I'm going to say you were working on an NA :) That's a popular one.

NB is a single line system.

Have you tested to see if you have spark? 

Thanks guys! As Keith mentioned, its a NB so I'm sure the fuel lines are connected correctly being that there was only 1 line I had to disconnect. I am going to head to Autozone to purchase an in line spark checker to check spark, so I will report back on there.

Now, I did go into the Megasquirt and try to poke around there. I am no expert at all with Megasquirt, and did a rough tune before starting the turbo install on my Miata while it was naturally aspirated. I have a tuning appointment in May for the car, so I'm just trying to move as quick as I can.

One thing I noticed is, while cranking, the Megasquirt is reporting an injector pulse width of 0. Seems like the injectors aren't firing, or is the pulse width of 0 normal during cranking? Any other tips on what I should look at in TunerStudio while connected to the Megasquirt? I apologize; I am a noob when it comes to tuning and ECUs.

I did take a datalog of cranking, so if anyone who is well versed in Megasquirts wants to take a look at it, I can somehow get it over to you, since it looks like files can't be uploaded here. I tried looking through it myself, and what I found was the MAP did drop, but it also looks like there is a spark advance of 0 during cranking. So looks like I also have no spark?

Thanks for any help I can get with this, I'm anxious to get it started so I can continue onto the next part of my build before my tuning appointment!

Do you have an RPM signal while cranking? It will not run otherwise. That drives everything. 
 

If not, remember that crank sensor people keep mentioning? Check the air gap, the connection and if the trigger is backward. Also, make sure the cam sensor is in place and plugged in. 

What did you do to the engine while it was out?

You don't need a special tool to check spark. Pull a coil pack (if it is cop) and put a spare plug in it. Ground the plug and crank it and look for a spark.  Otherwise just pull a plug wire and do the same. 

Keith Tanner said:

Do you have an RPM signal while cranking? It will not run otherwise. That drives everything. 
 

If not, remember that crank sensor people keep mentioning? Check the air gap, the connection and if the trigger is backward. Also, make sure the cam sensor is in place and plugged in. 

What did you do to the engine while it was out?

I will check my datalog again, but I believe the RPM during cranking was also showing 0. I will take a look at the crank sensor as mentioned before. I'm not sure what air gap is, so I will have to look into how to figure that out. I will check out the cam sensor too.

What I did to the engine while it was out is replace the front and rear oil pan seals, drill and tap the pan, then install a turbo drain fitting, reseal the pan, install new Mazda competition motor mounts, delete the A/C, install a turbo oil feed tee at the oil pressure sender, deleted EGR tube and solenoid, installed a coolant reroute, and installed a new throwout bearing on the transmission.

EDIT: You know what, now that I see what the crank position sensor looks like, I did indeed remove and reinstall that while installing the oil pan. What should I look for when looking at it? I had no idea it may have a certain orientation, etc.

No point in checking spark until the ECU knows the engine is turning. 
 

Air gap is the gap between the teeth and the sensor. It's 0.040" iirc. Too close is okay, too far means no signal.

Keith Tanner said:

No point in checking spark until the ECU knows the engine is turning. 
 

Air gap is the gap between the teeth and the sensor. It's 0.040" iirc. 

 

Got it, thanks! I actually just edited my above post, and I did actually unbolt and then bolt the crank sensor back onto the car while installing the oil pan. Is there a certain orientation it should be in?

I cannot thank all of you enough. My crank sensor was just too far away! Moved it closer, and it started right up! I am relieved, thank you everyone for the suggestions and help!

Victory!