Power to Ecu, But no fuel or spark?

[[TRE05]97ka24DE]

I just installed a redtop and have a #62 ECU. No spark to the plugs and fuel pump wont turn on. Checked ignition and power wires to the ECU, and read 12volts. so I was thinking maybe a bad ecu, Opened it up and didnt see any burn marks. Plugged it up to see if Ecu would turn on and yes it has power because Red light in the back turns on. Also Ecu relay works because I can hear it click on and off. But my main issue is in the dash cluster in the ON position the check engine light isnt on?????

[[TRE05]97ka24DE]

anyone???

[[TRE05]97ka24DE]

today I tested wires going to the ecu. and the start signal wire read 12v while cranking. but the fuel pump output read 0 . So I put 12V to the wire and still NOTHING!!!! why is my fuel pump not turning on.

[drkidd22]

Check your fuel pump fuse and the fuel pump relay. Pin 104 of the ECU goes low and activates the relay, so check that wire for continuity. When you turn the key to the ON possition do you hear the fuel pump turn on? check all your wiring for continuity, one by one. What car is it? 97 240sx?


Modified by drkidd22 at 7:33 AM 3/19/2009

[[TRE05]97ka24DE]

thats for the response. I checked the 104 plug yesterday and when the ignition was in the on postion it had no power coming from it. what it seems like is that power and all inputs are goin to the ecu but the ecu wont respond. Its an s13 redtop in a 97 240sx. today im goin to try to bypass the fuel pump relay to see if it will turn on.

[drkidd22]

You will not see power on ECU pin 104. It just grounds out(goes low) to acctuate the relay. Power should be coming out from the relay to the pump, not pin 104.

[[TRE05]97ka24DE]

I will try and ground it out. and see if the fuel pump turns on

[[TRE05]97ka24DE]

I gounded the wire out and nothing. fuel pump did not turn on. I cant find the fuel pump relay for the s14 to bypass it. but when I grounded out the wire shouldnt that have grounded the relay which would turn on the fuel pump on? but nothing happened??? and still the check engine light will not come on when the ignition is in the on position.

[drkidd22]

You can find the relay by testing the wires, I'm not sure, but I think the fuel pump relay is behind all the fuses on the driver's seat (look at the FSM), and if it is there, it's a pain to get to it, did you find the fuel pump fuse??. Other than that start from the back. You can put voltage directly to your pump then. You might want to take it out and put it in a bucket of gasoline to test. You can test it on the car too. Just unplug the fuel pump connector on the trunk take your battery to the trunk and apply voltage, watch for the right polarity, Use the FSM. BE VERY VERY CAREFULL, A SPARK CAN TAKE YOUR LIFE. DO AT YOUR OWN RISK.

[drkidd22]

I just looked at the FSM and the fuse(15A) is on the driver's side fuse panel and the relay is right behind it. With the ignition switch OFF, unplug the relay then turn the Ignition switch ON, Put the meter ground lead to chassis and with the red lead see if you have 12V on pin #1 and #3 of the relay.

[[TRE05]97ka24DE]

tripped the fuel pump relay. Fuel pump turned on. found out the problem. i checked the 104 Black/red wire from the ecu to the fuel pump relay and there was a break in the line. On s14s theres a dash plug that gets wired in from the white plug near the ecu. and that black and red fuel pump wire gets rewired to black/pink wire on the s14 plug. after closely looking I relized there are 2 black/ pink wires on that plug and the wrong one was wired up. rewired it and checked the line with the meter everything checks out but the relay still wont run on by itself. thinking I need a new ecu. and still no spark????

[drkidd22]

Ok, so the pump problem is fixed right? Well at least you kinda have an idea of what it is. Now do your timing and make sure it's correct, test the power transistor, and all the wiring going from the power transistor to the ECU, if one wire was broken I won't find it strange that you will find other wires broken too. If I were you I would take out the complete hardness and gut it out and test each single wire, use the schematic. I had similar problems to what you are having and I found my hardness burned and wires making contact, it had tape over it, so just an advice.