If this is in the wrong forum section please delete.

Me and my friends did our first motor swap on a 98 z-28, we took the old ls1 out and installed a new Gen III Iron 5.7. During the motor swap we installed new clutch, ls6 intake, long tube headers, and all new sensors, Anything from crank sensors to oil pressure sensor. We also ran black nylon hose for a new fuel line going into new fuel rails.

So after we got everything in and after we primed the system of course, we go to start it and the only thing that happens is that it turns over but no fire. So we checked and we have no spark and the fuel pump is not kicking on. Also we have no gauges.

We have checked all wires, fuses and relays and everything seems fine, we have been looking all week for anything but we are having no luck. So now we are asking for help. Any ideas?

 

Did you re-install ALL the ground wires?

 

Did you use the correct reluctor wheel? 24x or 58x?

Do you have RPM signal?

It could be any number of things.

 

Sounds like your not getting power through the circuits. Have you checked all your connections?

 

Fuel pump should come on at the turn of the key and your fuel pressure should come up on the fuel rail.

 

Make sure your getting power to the fuse box. Could also have a bad fuel pump relay if your getting power but not at the fuel pump.

 

Yes, we made sure the right reluctor was on and that was a 24x along with the right crank sensor.

And negative, we are not getting a rpm signal. We are not getting any signal on gauges. No rpm, no fuel tank level, no oil presser, no water temp, and no battery. Which is wierd bc we are getting the motor to turn over but its not giving me the volts on the battery. The only light that comes on is security?

Can a relay go bad just sitting? I have no proplem buying a new one but i dont want to start chasing problems.

 

have you checked for any DTC's? I know you may not be getting a RPM signal on the cluster but you need to see if the PCM is seeing it.

If the CAN BUS is down nothing will work on the cluster except for maybe the speedo, depending on what year it is.

Check for DTC's. My guess is you have some.

As mentioned check all of your grounds. Does the BJB have power to it?

If all you did was just an engine swap it sounds like you forgot to hook something back up.

 

Ground wire on the back of the driver side cylinder head. Ground wire from the harness near the alternator power wire that attaches to the frame and I believe there is another ground on the passenger side of the block.

 

ECM connections red and blue in the correct ports. Are the connections hooked up correctly near the passenger side kick panel.

 

Did u change anything in the ecm that might of tripped security? Or reactivated it?

 

I was also thinking the security as well. Maybe the VATS kicked on, but we did nothing to the computer but unplug it and pull it out of the car, surely that wouldn't affect anything. all fuses have been tested. checked for every ground. all sensors hooked up correctly. correct 24x wheel. everything seems in order verified via another running/driving fbody

 

This might be completly wrong, but i have been digging heavily into tuning the last few days. I read something in master efi tuner about the ecm not controlling the timing at startup. (I guess the ignition module does?) Then the ecm applied a signal to take over, so it could calculate misfires. I'm not sure if this would apply to your setup. I honestly dont remember what it was for since ive read so much tuning documentation the last few days. But if it is the case, perhaps that module is Not sensing whatever it needs to fire the engine. Maybe a simple missed plug or bad module? Could be the same power that activates it also activates the fuel pump?

again. This could be completely wrong maybe someone else can chime in.

 

Once you figure out what it was be sure to post it on here to help others who may run into this problem.

 

I'd be looking at the battery and alternator power wires and checking for proper routing to their respective circuits. You should have two main power wires, one to the alternator and one to the starter, and grounds for both. I could dig up a schematic if needed, but at least verify you have power going to the right places. If this is wrong, then you won't get any power to anything, which is what is happening here.

I doubt it is a relay or fuse. Your alternator might not be plugged in or something silly like that. You would still get power from the battery in this case though. There is a ground there from the block to the frame as well. I know everyone has said to check grounds repeatedly, but this is NOT a VATS issue, it's a power supply issue. If it were VATS, the engine usually starts then dies, and you will have the security light, as well as power to your cluster.

Check all wires from the battery. If needed, replace them. You might just have a short in your ignition circuit, or something is hooked up backwards somewhere, perhaps at the starter. I don't know, but I am just thinking out loud here. Check the power going into the fuse blocks too, (also on the battery/ignition circuit) and see what is going on there. You should a lot of hotwires throughout the car. Definitely anything that is hooked to the battery should have between 11-12v at all times, key or no key. If one of these wires is shorted out, then it could cause your complete loss of power, mainly the huge 2 and 4 gauge wires you see in the engine compartment. Check them all for power and ground, starting at the battery, and slowly working your way to the key, coil packs, fuel pump etc. Most of the "hotwires" or "hot at all times" wires are RED, PINK, or sometimes YELLOW or ORANGE <(some cases in the dash I've found).

A good wiring schematic is very useful here in figuring out what needs to have power and when.