e7ernal
07-08-2017, 02:38 PM
I have a s13 sr20det that was recently swapped into a s14 zenki. Bought a used wiring specialties harness from someone and the f3 plug wouldn't latch properly. At this time i could hear the fuel pump turning on but the plug was so loose even when latched it would just come out and turn all power to the ecu off. The pump was turning on but no crank. so, I zip tied the plug in place to prevent it from coming loose and found out the reason why it wasn't cranking was because the harness was meant for a manual and didn't have the neutral bypass plug so the next day I jumped the plug and it started cranking but now the fuel pump won't turn on at all.
So thinking it was the used harness I bought a brand new wiring specialties pro harness and the exact same thing is happening. I inspect the egi fuse, fuel pump fuse, pump relay, and ign relays. I have a spare s14 sitting in the driveway so, I take the corresponding relays and try swapping them and nothing. Even though the fuses also look good I replace them with brand new ones. At this point, I try jumping the fuel pump directly just to make sure it didn't crap out on me randomly and with direct 12v & ground it turns on, so the pump isn't dead. I test for voltage at the pump relay... nothing. So I decided to check the ECU relay to make sure the ECU is turning on. With the key in the "ACC" position, I get 12.4v on both the power wires but the moment I turn the key to the "ON" position the voltage drops to 1.1v.
The motor does crank still so I took out a spark plug and grounded to the firewall while we tried cranking and got spark so I know the ecu is turning on and somewhat functional. Tried swapping it out with another ecu and the same problem.
What would cause such a major voltage drop? The weird thing is the pump was being activated at first but then just randomly stopped. I have the entire dash apart and have tried countless things and cant seem to figure it out. Please if anyone has any feedback it would be greatly appreciated.
So thinking it was the used harness I bought a brand new wiring specialties pro harness and the exact same thing is happening. I inspect the egi fuse, fuel pump fuse, pump relay, and ign relays. I have a spare s14 sitting in the driveway so, I take the corresponding relays and try swapping them and nothing. Even though the fuses also look good I replace them with brand new ones. At this point, I try jumping the fuel pump directly just to make sure it didn't crap out on me randomly and with direct 12v & ground it turns on, so the pump isn't dead. I test for voltage at the pump relay... nothing. So I decided to check the ECU relay to make sure the ECU is turning on. With the key in the "ACC" position, I get 12.4v on both the power wires but the moment I turn the key to the "ON" position the voltage drops to 1.1v.
The motor does crank still so I took out a spark plug and grounded to the firewall while we tried cranking and got spark so I know the ecu is turning on and somewhat functional. Tried swapping it out with another ecu and the same problem.
What would cause such a major voltage drop? The weird thing is the pump was being activated at first but then just randomly stopped. I have the entire dash apart and have tried countless things and cant seem to figure it out. Please if anyone has any feedback it would be greatly appreciated.