Quote from
7.4 4x4 on December 4, 2025, 4:47 pm
I just got my 300002 back, they changed out the ECU. With the new unit, I now have a different wiring harness. They are sending me the engine side, should have it later today.
Before I get into the issue, I want to say that FiTech has obviously upgraded their customer service. For years, all I've heard about is how bad the Customer Service is. Well, I called on Wednesday, got an RA number, sent my unit in on Thursday. They tested it, cleaned it, put a new ECU in it, redid the wiring, and sent it back in 7 days, one of which was Thanksgiving. It was under 250. I am very happy.
On to the question: Obviously they have gotten away from the PWM fuel pump thing. Does anyone know why? They are now running a external relay box meaning the fuel pump runs at 100 percent all the time. I don't like that, I'm running this in a rock crawler, so it spends a great deal of time just off idle. Do I need to install an external fuel regulator after the pump to keep the pressure down at the TB? Is that constant pressure going to overwhelm the regulator in the TB? I'm running a 50101 pump, 240lph.
And second question: Does anyone have a wiring diagram for the new harnesses, the one with the three yellow wires ? Just want to see what's what on the new harness so I dont fry something hooking it all up.
I just got my 300002 back, they changed out the ECU. With the new unit, I now have a different wiring harness. They are sending me the engine side, should have it later today.
Before I get into the issue, I want to say that FiTech has obviously upgraded their customer service. For years, all I've heard about is how bad the Customer Service is. Well, I called on Wednesday, got an RA number, sent my unit in on Thursday. They tested it, cleaned it, put a new ECU in it, redid the wiring, and sent it back in 7 days, one of which was Thanksgiving. It was under 250. I am very happy.
On to the question: Obviously they have gotten away from the PWM fuel pump thing. Does anyone know why? They are now running a external relay box meaning the fuel pump runs at 100 percent all the time. I don't like that, I'm running this in a rock crawler, so it spends a great deal of time just off idle. Do I need to install an external fuel regulator after the pump to keep the pressure down at the TB? Is that constant pressure going to overwhelm the regulator in the TB? I'm running a 50101 pump, 240lph.
And second question: Does anyone have a wiring diagram for the new harnesses, the one with the three yellow wires ? Just want to see what's what on the new harness so I dont fry something hooking it all up.
