fuel injectors wont work

DRC77 · Post by **DRC77** » 12 Feb 2011, 21:21

I own a 200 s40. One day driving to work car just stopped running. The car will crank but will not start. I have checked and plugs are firing, I have replaced the fuel pressure regulator. And have looked into Injectors. I used a test light and no pulse is being sent to them to fire. I have looked at a relay that I thought controlled them and it is ok. Please does anybody have any ideas what to check and how to next I am so stuck. Thanks

Post by **JDS60R** » 12 Feb 2011, 21:34

I din't pull the wiring diagram but I am assuming the pulse comes on the ground side.

Check the ground side of the fuel injector with a "powered" test light for the signal. ( You supply the positive to the test light and the pulsed ground will allow the test light to light) If you have no pulse then check the computer to injector harness.

If you have a pulse then,

Check the fuses - if all of them are not firing then you have an issue common to all of them as you suspected with a relay.
Use the wiring diagrams above or your owners manual to track down the proper fuse.

Once you have tested for voltage at the fuse then follow the harness to the injectors for power. Once you have power and pulse it will modulate the injectors.

Post by **jimmy57** » 12 Feb 2011, 21:54

The power relay for coils, injectors, fuel pump, etc is only active when key is first switched on and then while cranking or running.
The injectors have a fuse of their own and it could be a chafed wire and blown fuse for the injector leg of fuel system power supply circuit. That you have spark says the crank sensor is good.
Check the fuses in engine bay fusebox carefully. Use a test light or volt meter on the test ports on the fuse. Fuses can look OK but still be open.

DRC77 · Post by **DRC77** » 13 Feb 2011, 18:08

I tested the ground by hooking a test light up to the positive battery terminal and unplugged the Injectors they all lite up. I then put the test light on the ground terminal and put in other side of Injector plug. Either when key first turn on or when cracking it did not light up. I looked at all fuses and can't find any bad and I can't find and bad wires. Is it possible that my Pcm is not telling the Injectors to fire?

Post by **JDS60R** » 13 Feb 2011, 18:20

It is possible but not likely.

With the test light hooked to positive -probe the ground side and observe while having a friend crank over the engine.
let me know if you see the pulse

We are looking for a ground pulse - ECM's rarely modulate on the positive side

Post by **JDS60R** » 13 Feb 2011, 18:23

Tell me what motor is in your s40 ???

You need to check for continuity between the fuse and the plug for the injectors. You need to find out where you are losing power.

DRC77 · Post by **DRC77** » 14 Feb 2011, 14:42

Car has a 1.9l motor. I haven't tracked positive wires yet but I did put my test light on the ground side. It was on and I had my wife try to start the car. The light did go off when cracking over but did not come back one until stopped cracking the engine. There was no pluse just went off.

Post by **JDS60R** » 14 Feb 2011, 19:11

Ok - thats not great news but lets track the positive side now.

Let us know.

Have you checked for codes??
Please check them and report back.

DRC77 · Post by **DRC77** » 27 Feb 2011, 09:56

Ok there or no codes. I am having a little trouble tracking the wires. After taking the wire loom off I can see they all have a red wire hooking all the Injectors , I guess that is the ground cause it lights up with the light test. Also each Injector has another wore with a color strip but where do they go..... all the wires r in bad shape being real.brittle and the insulation cracking off.

Post by **jimmy57** » 27 Feb 2011, 10:12

The red is from power supply relay. the other wires, each with different color combos, are the ground signal wires from ECM.
You should have 12V on the red wires for 1.5 sec when key is switched on or while starter is operated.

You don't have a blinking car symbol with an X over it on instrument when you crank engine over?