Thanks for reading my post. I have a '92 940Gl that appears to no be receiving fuel to the cylinders but it does get to the rail. It has spark and turns over fine but no ignition. Any suggestions on getting the injectors to operate? Thanks again.

 

are the injectors getting power? one wire, green, to each of the 4 injectors is common power, from the 'radio interference suppression' relay. the other wire, grey, to all 4 injectors is selectively grounded by the ECU to fire the injectors.

there's a gadget called a 'noid light', you unplug the injector wire, stick the noid light on the injector socket, then plug the wire into the noid light. Crank the car, and verify the noid light blinks. if it does, and you have adequate fuel pressure, it should be running.

if there's no 12V on /either/ wire to an injector, then check the RSR. I believe on non-turbo 7/9's, its behind the right headlight.

The RSR has 4 pins. pin 1 is chassis ground. pin 2 is connected to the fuel injection 'blue-yellow' power circuit by way of the other half of the fuel pump relay, this is the control power that turns the RSR on. pin 4 is connected directly to the battery + via a red wire. pin 3 is green-red to the green wires on each fuel injector, this is the switched power to the injection.

 

Thanks for the input. So far I have narrowed it down to the injectors. Its getting fuel to the rail since I replaced the fuel pump. Its getting spark but the cylindars don't seem to be getting fuel. I jumped the RSR and to no effect. So I'm guessing either the crank position sensor or the injectors are just too pluged up. It hasnt run in five years but I did get it to start and run for a couple minutes with starting fluid.
Thanks again!

 

did you A) check for voltage at the wires to the injectors, and if so, then B) run a noid light test? I would *NOT* replace any injectors unless both of those tests pass

btw, what does 'got fuel at the rail' mean? have you done a fuel pressure test?

if you're getting spark, the CPS (crank position sensor) is working, as its the timing for both spark AND injection.

 

Im going to get a voltage tester today. Good to know about the CPS, that was my next thing to check. In that case I would have to assume the fault is with the injectors. Yes I replaced the in-tank fuel pump as it was not getting fuel at all to the "fuel rail just prior to the injectors and now it does. No I havent checked the fuel pressure yet, only verified its getting fuel. I will next check for voltage to the injectors but am starting to think they are the culprit.

Thanks again!

 

unplug one of the injectors, connect your volt meter's black/- lead to chassis ground (or the battery - terminal), switch the ignition on, and touch the + lead to either pin in the plug that goes onto the injector.... one pin should be 12V, (the other will probably read some vague voltage thats not important). If you DONT see 12V on either pin, then there's a problem with the power supply. pin 4 of the RSR relay socket should be 12V relative to ground at all times, as its supposed to be directly connected to the battery.

 

I checked the current to the injector and it has good power. This leaves me to conclude that the Injectors are fouled up as I cant notice any fuel getting to the cylinders. Definately to the rail though. Power is definately good to the Injectors.

Thanks again,
Cheers!

 

Thanks again, do you know if testing the Radio Suppression Relay is possible? Also is it possible to test the injectors with a common voltage (light) tester? I am guessing not as the ECU modulates the pulse by controlling the grounding.

Thanks,
Tim

 

I highly doubt that the issue is with your injectors. They are highly reliable and I have never had one fail on the three cars I have had. If you are getting power to the injectors then the radio suppression relay should be ok as it provides power to the injectors. You really need to check with a noid light as Pierce suggested since getting power to the injector is the first step. The ECU then grounds the other pin of the injector to get it to fire. It is these pulses that you need to check for with the noid light. Without the pulses the injector won't fire.

For a noid light I used an LED connected in series with a 680 ohm resistor. Connect it in parallel to the injector. As you crank the engine you should see the LED flash. Keep in mind that LEDs are polarized so you might need to swap the leads around and try it both. If you don't get a pulse either way then your injectors won't fire.

 

Thanks for the reply. I havent ever had injector problems in any car, but this old man sat covered in moss for five years and figured they could have rusted or what not.

I understand about the noid light to diagnose if power is being supplied but it seems like it could still be faulty even if 12v power is being supplied to FI. I can definately see how it would rule out the ECU though.
Unless i'm missing something, it would have to be RSR, ECU or failed/clogged FI. However all I am sure of is it gets power (12v) to the FI,s as well as fuel (good pressure) to the "rail".

Its a bit confusing not being a pro mechanic and having so many variable systems for this make/model. It is the Regina fuel system and the new in-tank pump works good now, obviously the fuel pump/injector relay works , im assuming. So if its not clogged FI,s I have to assume a bad RSR or ECU.

Thanks!

 

the simple volt meter test (or test light) would show power is getting to the injectors or not.

 

Thanks a million Pierce. Problem solved. As Murphy would have it there where two issues. One a bad fuel pump and after loosing sleep and learning as much as I could about the ignition system...i found bad fuel and alot of water in the tank. Problem solved.

Tim