Unicorn Won't start

Long story short, I purchased a speed6 as is (not running), put it all together and now it won't start. When I received it, the engine was 're-manufactured'. The engine was mounted to the car, but nothing was really hooked up. I installed all the hoses/wires/turbo/etc..

When turning the key, all I get is tons of clicking but won't crank. Very rarely, I get it to turn over. I've tried cranking it for 30 seconds at a time with no success. But it's about 1 in 10 times it starts over, each attempt is usually a day apart (typically because I run out of time troubleshooting).

Things I've done so far:
Replaced battery
Replaced starter
Replaced starter trigger wire
Verified voltage going to the trigger wire
Verified all fuses in the engine bay and under the drivers side dash
Verified continuity to any visible grounds I can see (including the HPFP ground).
Swapped relays around the fuse block
Verified continuity between the starter power wire and the battery
Bypassed fuel pump resistor

It's driving me nuts. Since I don't know the history of the car, I'm starting to think it's an electrical issue.

 

I would be concerned about the engine. Try to get a compression test on it when you can get it to crank. I wonder if it is in the ignition switch.

 

I started a compression test and realized I can't because it won't crank lol. Was pissed once I realized that.

 

May be frozen up. Got fuel, spark, ground?

 

What kind of clicking are you hearing? This is with a fresh battery and a booster pack attached? What is the condition of your battery terminals?

Define "Turn over" in terms of what you have seen, that statement can mean many things.

1/10 times it starts and runs? or the starter motor cranks? When/if it cranks, is it uninterrupted/healthy cranking?

Any other lights on the dash?

Most common reasons this platform fails to crank from my opinion:

- Poor connection to the starter motor signal wire. The single pin spade connector. Sounds like you replaced this, but have someone try to crank the car while you move this connector around. Spade connectors suck for longevity in such an environment.
- Main Relay in the fuse box. This is more common on the 3s, not sure if it is similar on the 6s.
- Start motor failure. Looks like you replaced this. IF this is still suspect, try to hold the key in the crank position longer than usual, but don't overdo it.

 

As the big dill pointed out it could be starter motor failure if you're only hearing clicking. Check your starter

Now my buddy had something similar when we reinstalled his engine, we remounted the started for whatever reason the gear didn't line up properly and weren't catching so a simple off and on solved the issue.

 

I just got this fixed. Remove the serpentine belt and confirm that all of the accessories turn. My alternator would not turn even with a breaker bar on it. Car would start easily with no belt installed. Obviously shut it down fast if the belt is off