I have made my own harnesses in the past with success but I made the mistake of thinking 160bucks was worth not hunting a harness at the yard well that backfired. It's an ebay harness with 2 starter positives and only 1 ground to cylinder head and one ground to the relay box I get 12v at my coil connectors but only 5v at the injectors but when I ground the injector plug to chasis it reads 12v but it only reads 5v at the connector it self vats has been deleted and it does run on starter fluid it's very frustrating because my swap is complete it's just this hiccup any help is greatly appreciated what should I check is there resistance or anything I have good ground to the block battery and chassis so it's all very confusing

 

Do you have a set of NOID lights? If not, you can rent/borrow them from your local auto parts store. Plug one into one of your injector connectors to see if it illuminates as you crank the engine over. if that light will light up, then you should have enough juice to fire the injector. I think. Are these NEW injectors? Or have these injectors been allowed to sit with fuel in them? If they have been allowed to sit with fuel in them-the fuel dries up and essentially sticks the injector SHUT inside not allowing any fuel to flow. You can test this theory by pulling one injector off the rail and taking it to your work bench. Using compressed air with a rubber tipped nozzle you can pressurize the injector with air-then with an old car battery you can apply a ground and 12V positive to see if the air will then flow through the injector. If no air flows through the injector, then the injector is stuck. It's common. It happens. If it is stuck-remove the air nozzle and fill the injector with brake cleaner=then put the air back on it and connect to voltage.. When the brake cleaner starts flowing out the injector-you will have sorted that one... Now you only have 7 more to go! I've had to do this on MULTIPLE fuel rails that have sat for as little as 2 weeks with fuel in them.. The fuel dried out and my problems began. Just like your situation the engine would run with brake cleaner being sprayed into the throttle body.. But no fuel flow from the injectors. Don't ask me how long it took me to figure this out the first time.

You also need to check that the fuel pump relay is being energized when you first turn the key on to PRIME the pump, and that it is also running when the engine is being cranked. If the fuel pump is not being controlled properly-no fuel, no fire.

Lastly, if you don't have a noid light kit, or don't want to borrow one.. Pull one side of the injector rails out of the intake and crank the motor over.. if no fuel coming from the injectors-it has to be one of the things I've listed above. Either no fuel to the injector, or plugged injectors, or electrical issue.. Simple right?

 

I appreciate you taking the time to reply and offering me your help, theres no need for noid lights here as ive been probing this issue with my dmm it seems my issue is more electrical , I wish I could up load a video here but the pcm is commanding the injector harness , my issue here is that the voltage at all the unplugged connectors is not 12v its only 5v which won't open injectors at all I'm really trying to figure out why I only have 5v at those connectors and not 12v hopefully someone else has had experience with these Chinese harness that can chime in

 

Your PCM has several 5V power pins in it for other sensors on the engine. Your injectors should be getting power from an external power source. If your injectors are getting their power from an external power source it is not possible that they are getting 5V as there is no other 5V power source (on most cars?) that has 5V. This should be VERY easy to figure out. Ohm one of your injector wires-it should go back to ground. Then once you have identified your power wire trace it back to see where it goes. If you truly are getting 5V at the inj. connector it can only mean that your injectors are being powered by the PCM which is NOT correct. I could have this settled in under 5 minutes. Think about it... NO WAY 5V only is getting to the injectors UNLESS the power for the injectors is coming from the PCM. Most stand alone harnesses also have a small fuse box... Figure out which wire is powering the injectors and while testing that wire for voltage-pull the fuses one at a time until the power goes away. If the power never goes away-then your harness is pinned wrong and you are getting 5V from the PCM (or one of your fuses just killed the power supply to the PCM and you have also lost your 5V source). Also, you could pull the fuses one at a time and look for continuity between the contacts for the fuse, and your power supply wires for the injectors. One of those fuses providing 12V MUST be connected to the power supply wires for the injector. If the vehicle were here, I'd have this done and over with in under 5 minutes.

 

When I probed cylinder 2 injector connector it had continuity with every fused power wire there's 4 positive 12v outputs and injector 2 is somehow connected to all of them I'm not good at diagnosing and this harness truly has given me a big headache that I'm not gonna mess with it anymore I've simplifies junkyard harnesses before with success so ima just ditch the China harness and im going to the junkyard tomorrow I appreciate your time man I really do
edit- 2 hold on I just tested my tach signal wire it's coming out of correct pin off the ecm but its also tied into a 12v power source so it's back feeding 12v into pin 10 on red connector what would that do???
edit 3 I appreciate your help it seems i have it sorted it out turns out pin 63 was missing on blue connector i added that i fixed the tach signal back feed and it seems there's continuity between all injector positive to the cylinder head grounds so ima gonna strip the harness lol thanks for your help

 

I'm in the same boat as you. I too am battling a Chinese harness. And i too am going to be having to just do what i should have done in the first place and reworked the original harness like i have done in the past...

 

your better off just stripping the harness and finding the issue my tach signal was directly tied into the fuse block so I fixed that also pin 63 on blue connector was missing i added and fixed that it apears that my injectors have continuity to ground itll be easy to fix and it'll be worth the fix since I would have to modefy a harness anyways , its all the same. im also gonna move the power wires and ill add fuses to them because I don't want my car to burn to the ground ima fix this harness but it'll definitely be the last ebay harness that I purchase

 

If you guys give up on the Chinesium harnesses-I'll gladly buy them from you. If you decide to ditch them-send me a message. I'm certain I can dig through them and find/fix whatever the faults are in short order.

 

I appreciate that and I got the harness stripped right now if I can't find the short I'll gladly sell this thing at a loss