KA-T No start (Spark and Fuel)

[ceezer]

I will attempt to be as descriptive as possible. 1992 KA24deT, some 200k on chassis, about 180k on 1991 swapped dual cam.

Short version: Fuel pump not priming, no spark at all.
Have tested: ECU, Relays and fuses, Coil, power transistor, CAS, Dizzy,

Longer version:
Went ahead and installed a turbo kit (t25 bottom mount with ecu for 370cc injectors, n60 mafs), adjustable SARD fuel pressure regulator, and gauges (boost, aftermarket tach, oil pressure, and oil temp). After completing the job, the car started and was allowed to run for about 30 minutes while burping radiator and checking for any leaks. Shut the car to fix the tachometer and when we went to start it, it cranked but didn't turn over. The fuel pump (walboro 255lph) would not prime and it was later on that we also found it to not be sparking. To temporarily get the car going, we ran new wire running from the battery to a switch to the fuel pump. At this time, the fuel pump primed, stayed on, and showed the correct fuel level.
Next, to diagnose the no spark, we pulled out the entire ignition coil and chip, with bracket and all, and placed it into a working 240sx and sure it fired up just fine. To test the CAS and dizzy, we took it out and put it in the known working 240 once again and it fired up. Using a test light, we tested all power transistor wires and discovered that the white wire (coming from ecu pin #1) was not lighting up when connected to the test light. It did, however, have continuity.
Onward in our investigations, we swapped out the ecu for the stock one (again only temporarily) but still no spark. We have swapped all fuses and relays from the donor 240 but nothing.

Help is needed. Please and thank you all.

[rcdad123]

look for a wiring diagram for your car and find out where and what that white wire you are talking about goes and does. if its a signal from the ecu, ecu could be bad. if its a signal from a sensor going into the ecu, check and make sure that sensor is not shorted out. or if you want to install your injectors and ecu on the donor 240 and check if that runs, then ecu is good. good luck and please post if you find the problem.

[mxexux]

whoa let's backtrack here to the important part... What exactly did you do to "fix" the tachometer. This is obviously where something went wrong since the car ran before and not after. Try undoing whatever you did to the tachometer and try starting it again.

[ceezer]

look for a wiring diagram for your car and find out where and what that white wire you are talking about goes and does. if its a signal from the ecu, ecu could be bad. if its a signal from a sensor going into the ecu, check and make sure that sensor is not shorted out. or if you want to install your injectors and ecu on the donor 240 and check if that runs, then ecu is good. good luck and please post if you find the problem.

It's a signal from the ignition chip going into the ecu (pin 1) btw its a straight shot with no relays breakers or fuses in between. I also already tested both the ignition coil and chip on the donor 240. also tested the tuned ECU on the donor 240 and it turns out it went bad so I tested my stock ECU and it started on the donor but not mine.

[ceezer]

whoa let's backtrack here to the important part... What exactly did you do to "fix" the tachometer. This is obviously where something went wrong since the car ran before and not after. Try undoing whatever you did to the tachometer and try starting it again.

I'm almost positive now that I fried my harness as well as the ecu when I messed with the tach. instructions on the tach state to run the sensor wire on the negative from the coil... I wired it into a black wire but it turns out it was a signal wire and not the ground wire.

[Taylor008]

More likely that ECU is fried than harness.

Dork. Why didn't you use the existing tach wire?

[ceezer]

I got a new ecu and wiring harness and still nothing. and once again i tested the ignitor chip, ignition coil, all the fuses, relays and the dizzy on a donor car and she fired right up. we tested both the chip and coil and they both get power but neither is grounded through the harness. any one know why that might be? again its a new harness

[OrangeVirus1]

there is 4 things needed to get a car to start :
air
fuel
compression
spark.

if it is getting fuel and spark, it is either not getting air, or not compressing.

[Taylor008]

With key on/engine on, does your ECU's red light glow? There's a little window you can look through.

[lougskypes]

you are right,neither is grounded through the harness. any one know why that might be? again its a new harness.thanks http://www.maxin.us/imax/images/3.gif

[ceezer]

okay so i went out and swapped in a new ignition switch and still nothing
again fuel pump is turning on via switch car is cranking but not turning over and all the spark components were tested on a donor car and they all checked out good but once everything is back on my car i don't get spark. i checked 2 known good ecus and neither one lights up... i might have fried them both but i will find out for sure tonight on the donor 240. i also switched out all the relays and fuses just in case.
fyi when i have the key to the on position everything that should turn on inside does except the fuel pump but again i ran that through a switch. perhaps the fuel pump and no spark are the result of the same problem

[NinjaX]

okay so i went out and swapped in a new ignition switch and still nothing
again fuel pump is turning on via switch car is cranking but not turning over and all the spark components were tested on a donor car and they all checked out good but once everything is back on my car i don't get spark. i checked 2 known good ecus and neither one lights up... i might have fried them both but i will find out for sure tonight on the donor 240. i also switched out all the relays and fuses just in case.
fyi when i have the key to the on position everything that should turn on inside does except the fuel pump but again i ran that through a switch. perhaps the fuel pump and no spark are the result of the same problem

check for resistance in the wires, if u get OL its an Open, 0.0-.9 good connection, if u get any thing higer u have resistance. Even if there is Continuity it still doesnt test for resistance same with the test light.

[Taylor008]

Why are you asking for help but not reading my posts?

I don't think you're getting ECU power.

[milto0n]

Why are you asking for help but not reading my posts?

I don't think you're getting ECU power.

Where does the ECU draw its power from?

[godrifttoday]

More than likely your distributor 180 degrees off, take of the distributors and make sure it lines up to the marks,

[Taylor008]

Where does the ECU draw its power from?

Ignition> to gray harness clip by the battery.

ECU switches the ground for the fuel pump. Pump always has power. If fuel pump is not priming on it's own, ecu is not turning on.

[ceezer]

Ignition> to gray harness clip by the battery.

ECU switches the ground for the fuel pump. Pump always has power. If fuel pump is not priming on it's own, ecu is not turning on.

Dude! :eek2:
This makes so much sense. I'll check that out tomorrow morning.
please excuse my ignorance BTW i didn't understand you before.

[ceezer]

Milto0n you b*tch when you gonna come help me make her run?

[Driftwire]

Def sounds like your no getting any power to your ECU. Some fried ECUs will even show a Red light.

>.>

[ceezer]

which pin would i use if i wanted to run a wire from the battery to a switch to that pin? is it pin 36 or 38? i just checked and 36 is ignition switch, input and dedicated while 38 is power suply for ecm +12v, input and switched.
thanks again in advance