Help, No start after performing maintenance.

[aworthybrother]

My m42 (140,000 miles) was running perfect since I parked it last year November. I then started fixing the mess under the intake and while I was in there, I had the fuel injectors reserviced. Also, while in there, I replaced all 3 belts, thermostat, thermostat housing and water pump, cleaned the ICV and throttle body.  So after putting everything back together, I turn on the ignition with engine off and started putting coolant slowly with the heat set to the highest to prepare bleeding the coolant system. When I tried to start the car, it just cranks and would not start.
 
I then replaced the battery, the crank position sensor, cam position sensor even though the volt-meter reading was good. I also removed the intake manifold again to check on the fuel rail and there's fuel.  I also reseated the fuel injectors (it has new o-rings), also replaced the plugs.  When I removed the old plugs it was dry and not sure if fuel is reaching the combustion chamber. Also checked the fuses and they are all good, but not the relays. Dont know how and which relays to check.
 
Also, while doing the mess under the intake, there are 2 sensors by the engine block for the coolant, I dont think I messed up those 2 connections because 1 has 2 pins, the other has 1.  But bentley said another reason for a no start is a failed coolant sensor? Is this correct?  I havent tested those 2 sensors with a volt-meter.
 
Since the car was running perfect before performing these said preventive maintenance, Anything specific I should check that I could have messed up while performing any of the above procedures?
 
Appreciate any help.

[DesktopDave]

Coolant temp sensor wouldn't kill the motor.

I'd verify that your fuel lines are correct.  The relays you should check are the three on the firewall.  They're for the O2 heater, the fuel pump and the main power.  Do you get a check engine light?  If that lights while you're turning the car on, the DME is getting power.

I'd suspect the DME is being wonky & not priming the fuel system.  Typically that's from the crank sensor not sending a clean signal.  Is the gap on the sensor OK?  Resistance readings in spec?  680 ohms IIRC.

[aworthybrother]

Coolant temp sensor wouldn't kill the motor.
 
I'd verify that your fuel lines are correct. The relays you should check are the three on the firewall. They're for the O2 heater, the fuel pump and the main power. Do you get a check engine light? If that lights while you're turning the car on, the DME is getting power.
 
I'd suspect the DME is being wonky & not priming the fuel system. Typically that's from the crank sensor not sending a clean signal. Is the gap on the sensor OK? Resistance readings in spec? 680 ohms IIRC.

Check Engine Light works fine. Stomp test comes back with 1444.
 
Fuel lines are correct because the only fuel hose i replaced are the 2 short (3" long) hoses which in no way I can swap or criss-cross. When I replaced these 2 short hoses, and replaced the injcetors with the re-serviced one, the fuel rail was emptied with fuel during the process.  Then installed everything back together to start the car which failed.  I then removed the fuel rail to check, and there is fuel, meaning fuel pump worked to push fuel into the rail.
 
How do I check the 3 relays in the firewall with a volt meter?
 
Also, if all 3 relays are good, what else should I check?
 
Thanks.

[DesktopDave]

I test relays with a spare socket I salvaged.  It's hard to test them in the car, but if you have a buddy turning the car on and off you can hear & feel them them click.  I always carry spare relays and a few bits of 14 gauge wire in the trunk tool kit.

First I test the relay powered off...30 to 87 (load or switch side) need to have very high resistance (ohms) or no continuity (diode test on my meter).
Then I put 12v to the control side (that's normally terminals 85 & 86, polarity doesn't matter unless it's a diode relay) & test for low resistance/continuity on the load side (terminals 30 to 87 for a four pin relay).  Five pin relays are pretty similar...but 30 & 87a have continuity with no power to the control side.

Here's a great reference to relays:
http://www.autoshop101.com/forms/hweb2.pdf

You triple checked all your electrical connections too, right?  Are you sure the crank & cam PS are plugged into the right connectors?  They can fit in the wrong plugs and that'd keep the motor from starting.  What about the coils...if you worked on them, are you sure they all match 1-2-3-4?