Injector/Fuel issues (Stock harness issue)
11-06-04, 11:20 PM
#28
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Originally Posted by f1blueRx7
I'm saying, what should the Black Yellow wires measure AT each injector plug. Because it's measuring out to be (fluctuating) 5-7-0VDC. It's not constant. And I understand it should be 12VDC constant.
11-06-04, 11:26 PM
#29
There are two wires at each injector... Regardless of what color each one is... your saying only ONE wire should have voltage? Because that IS the current situation.
I'm sorry for confusing you. I was assuming the wire on my harness was B/Y because I was going based on the 88 High IMP diagram. I know that I can pull 12VDC Constant off the LG wires... but the other wire has no voltage.
I'm sorry for confusing you. I was assuming the wire on my harness was B/Y because I was going based on the 88 High IMP diagram. I know that I can pull 12VDC Constant off the LG wires... but the other wire has no voltage.
11-07-04, 12:23 AM
#30
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Only one wire at each injector should have voltage. It should be approx 12 or whatever your battery voltage is at that time.
The other wire on each injector goes to the ECU. The ECU only puts a ground on that wire when the engine is running. It pluses a GROUND to that wire to cause the injector to pulse. It does this in milli seconds. Only happens when the engine is turning.
If you put the injector plugs back on....and go to the ECU and pull the smallest plug off....and put your meters neg lead on a good ground like the ECU attach bolts....and the positive lead on the plug that you just pulled off at either pin 3C, 3E, 3F, 3H.....you should see battery voltage of approx 12v.
YOur not going to see any pulsing unless the small plug is put back on and the engine is running. You backprobe one or the above wires and you should see a voltage drop from whatever the alternator is putting out to the battery. Only the primary will have a voltage drop. The secondarys should remain a steady reading. Usually at idle you'll only see a one to two volts drop from about 13v. In other words maybe down to 10-11v or so at idle.
The other wire on each injector goes to the ECU. The ECU only puts a ground on that wire when the engine is running. It pluses a GROUND to that wire to cause the injector to pulse. It does this in milli seconds. Only happens when the engine is turning.
If you put the injector plugs back on....and go to the ECU and pull the smallest plug off....and put your meters neg lead on a good ground like the ECU attach bolts....and the positive lead on the plug that you just pulled off at either pin 3C, 3E, 3F, 3H.....you should see battery voltage of approx 12v.
YOur not going to see any pulsing unless the small plug is put back on and the engine is running. You backprobe one or the above wires and you should see a voltage drop from whatever the alternator is putting out to the battery. Only the primary will have a voltage drop. The secondarys should remain a steady reading. Usually at idle you'll only see a one to two volts drop from about 13v. In other words maybe down to 10-11v or so at idle.
11-07-04, 12:47 AM
#32
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Well, if you have approx 12v at each of those four wires, it ain't the harness.
It's also unlikely the injectors are bad. I've taken injectors that have not been in a engine for over a year and they work just fine and dandy.
If the cas is connected up, and you have 12v on each of the pins at the ECU for each injector......and the fuel pump is running.....they should be injecting when you crank the engine over.
Another AND is ...and if you have not been moving the fuel lines around on the engine. Sometimes the return and pressure lines accidently get crossed. Won't work like that.
Ever pull the plugs out and crank the engine to see if you have a mist of fuel coming out the plug holes?
Maybe swap in another ECU and try it.
Look and see if you have 12v on the black/yellow wire on the white, two socket connector at the LEAD coil assy. It should be there since you have 12v at the injectors. But check anyway.
It's also unlikely the injectors are bad. I've taken injectors that have not been in a engine for over a year and they work just fine and dandy.
If the cas is connected up, and you have 12v on each of the pins at the ECU for each injector......and the fuel pump is running.....they should be injecting when you crank the engine over.
Another AND is ...and if you have not been moving the fuel lines around on the engine. Sometimes the return and pressure lines accidently get crossed. Won't work like that.
Ever pull the plugs out and crank the engine to see if you have a mist of fuel coming out the plug holes?
Maybe swap in another ECU and try it.
Look and see if you have 12v on the black/yellow wire on the white, two socket connector at the LEAD coil assy. It should be there since you have 12v at the injectors. But check anyway.
11-07-04, 05:08 PM
#36
Well I did some more work today. Wired the injectors in to the rail (so they wouldn't pop out under pressure) and tested them, No spray. Wired them to a 12v powersource and they were spraying fine (per the FSM instructions).
So I started messing around with the wires down by the ECU. On the front harness -> Emissions harness plug I found a loose connection.
That wire indicated was making a clicking sound on the relays under the driverside of the dash. I replaced this wire and made a good connection and now I can hear this relay click on when I turn the car on. It still did not resolve the issue however. My next step is new harness/ECU.
Another thing I should note for you hailers, This is an 88GXL with a 87 turbo 2 motor, drivetrain, ecu, and harness.
So I started messing around with the wires down by the ECU. On the front harness -> Emissions harness plug I found a loose connection.
That wire indicated was making a clicking sound on the relays under the driverside of the dash. I replaced this wire and made a good connection and now I can hear this relay click on when I turn the car on. It still did not resolve the issue however. My next step is new harness/ECU.
Another thing I should note for you hailers, This is an 88GXL with a 87 turbo 2 motor, drivetrain, ecu, and harness.
Last edited by F1blueRx7; 11-07-04 at 05:14 PM.
11-07-04, 05:53 PM
#37
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No telling when Hailers will be back on, so I'll try to help you a bit...I tried to speed-read everything since I've last posted, and one question pops up- Have you read the 3 grounds from the ECU pins to the chassis? Two of them are on the same small ECU plug as the injectors, the third is on the middle plug, IIRC. All of these three go to the rear rotor housing ground. If the harness is good, and the ECU is good, the only thing left for correct injector operation is that ground.
Turn off all power on the car, read the ECU pins to ground (whichever pins they are in your application). Meter to resistance. Should get a couple of ohms or less (zero being what you're looking for).
Turn off all power on the car, read the ECU pins to ground (whichever pins they are in your application). Meter to resistance. Should get a couple of ohms or less (zero being what you're looking for).
11-08-04, 10:51 PM
#41
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If you're at the point that you're "grasping for straws", so to speak, the ECU checks will be more of a peace of mind thing now. Even if you can't start (or warm up) the car, a lot of information can be gleaned from most of the sensor readings.
So, is it worth your time? I dunno, what else do you have to do?
So, is it worth your time? I dunno, what else do you have to do?
11-09-04, 12:06 AM
#42
I think alot of frustration here would allieviated if I was to work around the problem and jump a few months ahead here by installing an engine management system. I'll go through the ECU tommorow with the meter and give a reading on all the pinouts.
11-09-04, 01:34 AM
#43
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injector problems
Sorry to interrupt, just reading this thread, I'm going through the same problem right now.(no fuel in one rotor) I just found a worn wire(It was rubbing under my cold air intake) coming from the solenoid resistor. Could it have hurt the ECU in anyway?
11-09-04, 01:49 AM
#44
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If I read right, you have 12v at the injectors and AT the ECU pins with the key to ON.
So, the way I look at it, you need to determine if you have spark. IF you have spark, but the injectors are not injecting, my guess is that for some reason the injector drivers in the ECU have gone **** up. So go look for spark. Got spark? Then get another ECU. used.
So, the way I look at it, you need to determine if you have spark. IF you have spark, but the injectors are not injecting, my guess is that for some reason the injector drivers in the ECU have gone **** up. So go look for spark. Got spark? Then get another ECU. used.
11-09-04, 01:52 AM
#45
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yeah, spark is fine on all wires and the rear rotor has fuel. The front one is bone dry. I had the entire engine bay stripped. Also did a street port and removed all the emissionsions. Sorry if i'm being a bit vague i'm just trying to keep it short.
what I was wondering is if a shorted wire(grounded) at the solenoid resistor could cause any harm.
what I was wondering is if a shorted wire(grounded) at the solenoid resistor could cause any harm.
Last edited by brent clement; 11-09-04 at 01:57 AM.
11-09-04, 11:07 AM
#48
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Shorted wire would probably blow a fuse, then nothing would be working...
No, the CEL won't show a dead injector...
Last time something like this happened to me (only one rotor working), it turned out that some injectors I had purchased from another forum member were rusted shut (yet the coils still read out good). Might want to check out that possibility also
No, the CEL won't show a dead injector...
Last time something like this happened to me (only one rotor working), it turned out that some injectors I had purchased from another forum member were rusted shut (yet the coils still read out good). Might want to check out that possibility also
11-09-04, 11:26 AM
#49
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Much appreciated. It seems i did way too many things at once and now I'm paying the price. LOL. Anyway, I guess I'll just have to sort it out one problem at a time. The cars been sitting for almost 2 years now. It ran fine when i pulled the motor.(just a coolant leak.o rings) Problem is I built another fc this summer so I didn't finish everything on the 86 at once. I'm gonna patch up the wire at the solenoid resistor and swap the injector and hope for the best. Do you know if ether will hurt the motor? Hoping it won't but I'm afraid to find out the hard way. I used to use it on my fb in the winter time and the car went 220 k before dieing
11-09-04, 02:04 PM
#50
I'm going to swap ECU's. I think I found the problem. That one wire I was referring to earlier that I re-ran because it was making a clicking sound... That wire fried the injector driver in the ECU I'm pretty sure of it. I'm going to do an ECU swap, and an injector cleaning for my primaries. Then I'm going to try it again.
wish me luck.
-Mike
wish me luck.
-Mike