OK, I did a swap about 6 years ago of a LSJ engine into a 1986 Lotus Esprit. Got and MEFI4B ECU with Painless Performance software and a custom wire harness. Life happened and I had to put this on hold to now (so never fired it up)

Fast forward to the present. The engine cranks and does not start. I have verified I have spark. I have a return fuel line with pressure regulator and gauge. Fuel pressure is 60 psi, Pulled the fuel rail out but kept it hooked up electrically. When ignition key is on, fuel pump comes on for a couple of seconds to build pressure than stops. When key is turned to start, engine cranks but the injectors are not firing. I noticed two things when the engine is cranking (a) fuel pump does not run and (b) the tachometer was reading zero. I suspect that it is not seeing a crank sensor signal.

The crank sensor is 2 position. I looked at the harness for the crank sensor. It is a twisted pair with a braid shield. The person that did the wire harness tied the twisted pair into one connector pin and then the braid was to another connector pin. He did this on both ends of the harness (the one end to the crank sensor and the other end to the MEFI4b.

I would of thought that each wire of the twisted pair would go to their own terminals that connected to the crank sensor (so one wire of the twisted pair to one terminal and then the other wire to the remaining terminal) ....and that the shield would then terminate to a ground in the MEFI4b.

Does anyone have insight on how the harness is set up for the MEFI4B for the crank sensor?

I am not able to reach the person that made the harness

 

I am very familiar with the LSJ running the MEFI ecu. Here are some of my notes I have taken over the years.

Crank sensor plug
Pin 1 - Red/white wire
Pin 2 - Clear/bare wire
Has shielding around both wires and are a twisted pair

ECU connector J1
Red/white wire to pin 10
Clear wire to pin 25

If that is correct on your harness, unplug the cam sensor and see if it fires. The MEFIs really dont care about the cam sensor but if for some reason its out of time, it wont start with it plugged in. Like you said, after the fuel pump primes and you go to start the engine, it should kick on the fuel pump as soon as it sees the crank start to spin.