Car cranks but wont start

Thanks Casey40510. how do you carry out a smoke test and a compression test?Don't you think the problem is with the ECU not supplying enough voltage to the injectors to open the nozzles enough to let enough fuel to be squirted out? What causes no distinct voltage pulses at the injectors leads? Thanks.

Hi, sorry for the long delay. I like to pull the vacuum hose from the brake booster and blow smoke into the hose with a machine, but there are lots of different ways you can generate smoke. One of the wires may seem like it looses power when the engine is cranked, but that is just pulsing from the engine control module. You would need an oscilloscope to measure the square wave-form that is created when the ECU grounds the circuit over and over, equal to 1/2 the number of RPM the engine is spinning. Compression testing is done by removing one spark plug at a time, screwing in the compression tester and cranking the engine. a few times. Of course, disable the ignition system so it doesn't try to fire and start. The gauge will show the highest amount compression that cylinder registered. It can show you a few cool things. For instance, if two adjacent cylinders register low, likely a blown head gasket. Now, I didn't see before that you said removing and installing the connectors at the ECU causes it to start. That is exactly where I would be. Try to start, if no start wiggle those wires without removing them. Try to start again, etc... I don't think the injectors are the cause if they are firing, I think the ECU is doing it's job, but I would need to see the square-wave from the injectors to determine that for sure. You can also look on the inside of the connector (male and female side), and see if you can identify corrosion, bent pins, cracked or frayed wires going into the connector, etc...