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Hi all, I was reading a post on Facebook where a shop reportedly a car came in with a freshly swapped SR20DET and when they began looking at the ECU map (Key on Engine off) someone noticed the intake and boost pipes had filled with gasoline which was leaking out, a result of the injectors being open when the key was in the ignition on position. I would assume the fuel pump was on the whole time the key was on as well. What's interesting is that a number of people in the comments mentioned how they had experienced the same thing with their swaps? I'm curious how this is even possible? From my 300ZX TT I'm familiar with the fact that Nissan's of that era ran constant +12v to the injectors. I always assumed injectors only fired when triggered by the cam and/or crank sensor or RPM signal? I don't doubt this shop experienced what they stated but if this is the case why wouldn't a stock Nissan with +12v constant supplied injectors flood the engine when the key is on but engine off? Is it only due to the fact that the pump only comes on for a few seconds with key on to pressurize the system? I'm genuinely curious what caused this situation if someone can elaborate. Thanks!
If the ECU isn't controlling the injector outputs and they are going to ground, then an injector being supplied 12V+ will remain open. If the pump is also running then the engine will fill with fuel.
Thanks BlackREx that's the only way I could see this happening - if someone applied direct ground to the injectors and the fuel pump was running. I guess I assumed the injectors were wired to the ECU correctly and wondered if there was a condition that could cause this to happen if the injectors were wired up correctly.
Can't really comment other than to say that some applications have permanent grounds and switched +12V, some permanent +12V and switched ground/return.
Get them wrong and you're either looking at full open or nothing.
I would hope it was found before the engine was hydraulically locked on the fuel in the cylinder - that would be a very expensive mistake!