1991 Honda CRX start issue

I bought a 91 Honda CRX with a B series swap about 3 months ago. Test drove fine. Got it home and drove it a mile down the road and the 60amp battery fuse blew, 50amp ignition fuse blew, the ECU fuse blew, and the ECU blew up. Troubleshooting for weeks I found several bare wires grounding everywhere that were installed aftermarket. I ripped everything out that was homemade for this swap and bought a professionally done harness. Installed all new fuses and ignition switch and then found no spark. As we are going through the coil and ignitor test bad. Change them both and still no spark. Figure the Cam sensor is bad. Got a whole new distributor and now I have great spark. Still won't start. Ran a 5v reference test and found the injectors read 9,11, .010, 11
Now I'm guessing if I unplug injector 3 and the wire goes to 5v then it's an injector if it does not then it's the wire. I also think there's more at play here considering the rest are way over 5v. I'm told fix the one and the rest get in line but I don't believe that one bit.

You're going to need 12v for these injectors to work

Noah wrote:

You're going to need 12v for these injectors to work

I understand that. I'm trying to see if my logic is sound in the sense that if I unplug the injector and still don't get battery voltage on the wire then the wire itself is shorted out somewhere? I also need to figure out why injector 1 doesn't read battery voltage as well.

If you unplug an injector and don't see battery voltage on the power wire, you could have a short, but this would likely result in a blown fuse, and 0v on the wire. (Short meaning copper wire touching ground)
Where as you are measuring 5v-9v, I think it more likely you are dealing with a voltage drop. A poor connection or high resistance somewhere between the injector harness and whatever feeds it power (fuse box, main relay, ignition switch). You'll need a diagram or some kind of service info to find the source.

Noah wrote:

If you unplug an injector and don't see battery voltage on the power wire, you could have a short, but this would likely result in a blown fuse, and 0v on the wire. (Short meaning copper wire touching ground)
Where as you are measuring 5v-9v, I think it more likely you are dealing with a voltage drop. A poor connection or high resistance somewhere between the injector harness and whatever feeds it power (fuse box, main relay, ignition switch). You'll need a diagram or some kind of service info to find the source.

So 5v reference signal doesn't exist with these cars? Key on II. I should see battery voltage on the wires the injector wires to ECU? That's what I'm trying to make sure is that the ECU is getting signal from the injectors. I still have a crank no start after going through and finding I needed a dizzy. Now I believe it might be fuel related even though when trying to start I can smell the fuel.

There is a 5v reference voltage, it just has nothing to do with the injector circuit. It is used on sensors like the throttle position sensor, coolant temp sensor etc.

The injector is fed battery voltage on one wire and it is controlled by the PCM supplying ground on the other wire.
So, in it's un-energized state, the injector will have battery voltage on both wires (with the injector connected) going all the way back to the PCM.
To verify the circuit isn't open or shorted you can simply check for battery voltage at the injector control circuits at the PCM connector.
From the test you describe, the injectors don't have the proper supply voltage, so this test is unnecessary at this point until you restore battery voltage to the feed side of the injectors in my opinion.

Noah wrote:

The injector is fed battery voltage on one wire and it is controlled by the PCM supplying ground on the other wire.
So, in it's un-energized state, the injector will have battery voltage on both wires (with the injector connected) going all the way back to the PCM.
To verify the circuit isn't open or shorted you can simply check for battery voltage at the injector control circuits at the PCM connector.
From the test you describe, the injectors don't have the proper supply voltage, so this test is unnecessary at this point until you restore battery voltage to the feed side of the injectors in my opinion.

When you say PCM are you referring to the ECU?

Monde wrote:

Attachment not found

Not sure what this is but I don't really want to download something like this.

Monde wrote:

I edited my previous post and added an explanation to it.

Wire color is proper. I wanted to rule out a short in light blue wire for injector three. Ran a test with multimeter and got a beep. Wire must be good. So now if I read your post right I should check to ensure the main relay is getting 12v at blue/white and also yellow/black. I have checked every ground wire involving ECU. When I touch my multimeter to the green/black and touch the other lead to a known ground I get a beep.

What is the engine and computer combo in the car?
I know you said it was a B series swap, but a concrete year/make/model of the donor car would go a long way.

Noah wrote:

What is the engine and computer combo in the car?
I know you said it was a B series swap, but a concrete year/make/model of the donor car would go a long way.

Engine is a B20 with a B16 head. They are OBD 1 and I have an OBD1 ECU with OBD 1 alternator and Dizzy. The ECU came from a running drive b swap that was just like mine from a 91 Honda Civic. The engine harness is professionally built from Monotech.

And yes, PCM, ECU, ECM etc...
But I should have responded in kind, sorry for the confusion.

Okay so after going out there and getting some readings I want to outline a few things to try and make it clear what I did. First I turned the key to on position 2. This is the position just before the starter engages to start the car. When the key went to on position 2 I heard the fuel pump cycle and the main relay click. These are good signs for a honda now for the wiring.

Ignition switch plug under the dash
Blue/White 12V

at the main relay these readings were taken with red probe going into the main relay and black probe on the closet body ground
Position 1 is a yellow wire 12V
position 3 Yellow/Black and 2 wires are going into this 12V
Position 5 Black/Yellow and 2 wires are going into this 12V
Position 7 Yellow/Black no voltage
Position 2 black no voltage
Position 4 Blue/white and 2 wires are going into this 0V
Position 8 green/black and 2 wires are going into this 0V

Fuse number 2 shows 0V inspected fuse and it is in good condition
here's where things get interesting and I will try to explain it the best I can after cycling the key again I got the below

red probe in Blue/white wire at the main relay
black probe in Green/black at the main relay
reading -12.51V
Green/Black to body ground 12V

This seems to tell me that the Green/Black might be having an issue? Green/black is supposed to be grounds and should not have voltage and the Blue/White should have power at the main relay. Where would you guys go from here? Trace green/black and see if I can find where both wires go and test them for resistance end to end or test resistance on Blue/white?

Crank no start. Infector 3 has 0 volts and injector 1 has 9 volts

Crank no start. Infector 3 has 0 volts and injector 1 has 9 volts

I also want to point out that your diagram doesn't have trh same color injector wires (if I am reading it right). Looks like red, red, yellow, yellow?

I have CODES!!!! I must have fried the cluster when all of this happened. New cluster and I can get codes. I have code 6 on a crank no start. I still have an issue with power to injectors though.

I have no injector resistor box. I am running injectors that don't require one.

Monde wrote:

I can't get a diagram for your car. The missing feeds to these injectors should not cause the car not to start. Is the engine flooded by any chance? Do we have fuel, Spark, compression, and even Timing? Have you tried an alternative Fuel Source?

The engine swap.makes it hard to get a diagram. Code 6 causes hard cold starts. I'm changing that sensor today and will see what happens from there.

Nothing good. So I have a fuel pressure gauge in my rail. Pump primes and pressure goes to 40 PSI. When pump turns off pressure goes away. Pulled injectors out with rail attached and turned the key. Injectors stay dry. Had my wife crank it and injector 3 is dumping fuel while injector 1 is barely putting anything out. 2 and 4 seem to operate as intended. I changed the ECT and I still have the ECT code. We think it needs the other temp sensor changed at the thermostat housing as well. As for fuel pressure dropping, I pinched off the the return line and cycled the key. I held pressure the whole time until I let it go then pressure dropped. From what I am being told there is a check valve in the fuel pump causing this issue.