1999 3800SC into 1986 GT. turn on key, fuel pump "primes" 3 seconds, turn it over, no start. if I crank it over for about 10 seconds( till oil pressure builds), then it starts and runs normal. Ideas ?? waiting for new "oil Sender"
I believe that the ECM is looking for a signal that the engine has started before re-energizing the Fuel Pump Relay. That's why you can finally get started, when the OP sensor sees enough pressure to close thanks to the cranking. It should be getting that signal based on starting with the 2 second prime, and the OP sensor is a back-up. Unfortunately, I've given away all of my manuals to do more research. Hopefully, someone can jump in and help with details. I can't remember which sensor provides the signal, but I think it's the ICM??
but the fuel pressure is Remaining at 50 PSI Before AND "while cranking", at no time is it dropping.
OK, so if you have fuel and air, then spark is the only thing left in the equation (unless the ECM is not firing the injectors for some reason). Without the 3800 manuals, I'm unable to research this further, but it sounds like no issues now with OP switch, FP relay or regulator- all of those seem to be dong their job. I would focus on the ECM ( see if the injectors are firing right from the start), and then go through the troubleshoot guide for the ICM.
It DOES have both power/pulses to the injectors and spark to the plug as soon as it's turning over. the pulses don't seem to coordinate with the "spinning" rpm of cranking. seems like 1 pulse per 2 revs, maybe 3
Try spraying some starter fluid into the intake. If it starts immediately then this will confirm that it's a fuel system problem. Helps to narrow down where to look for the problem.
