w3lfd

I searched the forums and haven't really found any post specific the the l-jetronic on this issue. Here is what I know, I'm hoping someone can help me out.

- Good spark, just replaced plugs. Engine will start and idle briefly with starter fluid.

- Directly after installing new plugs, i tried to start and then removed a plug to check for fuel. The plug was completely dry.

- Checked end of fuel rail for fuel pressure, good to go. Pump is a' pumpin.

- Compression is good (155' ish). Again, runs on starter fluid.

- I have no tach when it starts with starter fluid, I'm hoping this is an indicator of what my problem may be.

This is my first encounter with the l-jetronic. From what I've been able to glean on these forums so far, it seems that the fuel system is somewhat dependent on the "green wire". (I just check the wire from dist to harness, and it gets continuity on both wires) Am I right in assuming this?

Guess it boils down to, what should I look at / test from this point forward to try and get the injectors firing?

Thanks beforehand for the help. I would love to get this baby running.

Shark Attack

I had an 84 that sat for a long time and would not start. i had everything you have.. I put a scope on the injectors and was also sure I had pulse to them.. It turned out my injectores where reall really dirty

w3lfd

That's probably my next step once I determine whether the injectors are getting signal. Is there an easy way to test this without an o-scope?

John Struthers

while the injector condition on the oldie's is always suspect...
Before you start yanking harness and injectors with the everpresent possibility
of breaking the connectors/wiring do a proper fuel volume flow check off the pump.
Just because you are pumping fuel doesn't mean you are maintaining volume or pressure.
The caveat is that you actually gauge tested for fuel pressure at the rail.
Doesn't sound like a relay problem at all.
Some other thoughts.
If you have been tinkering :
Check the harness connector to the AFM.
If you have never removed the AFM, do so and clean that puppy up. easy job rating.
Look for fuel in the valley.
Check the lines to the auxilary air regulator, cold start valve, and air valve.
Used to be: Temp sensor -one on dash or, the one in or close to the alt. cooling
tube hiding behind the front left wheel well splash shield caused start issues.
Also take a look around the distributor.
good luck, let us know how this turns out

Easy stuff first

Podguy

I will bet when you started on the project you changed the battery - right?

On the right of the battery terminal is a secondary accessory wire. This is the wire that supplies power to the computer. It is common for people to loosen this wire when installing a battery and not tighten it back up. Since the car has been sitting for a while clean this wire and make sure it is tight. Power for the rest of the car branches off the starter. Power for the computers comes from the secondary leg so it is easy to miss.

Second place to look is the grounds. If the car has been sitting for a while you should consider cleaning all the ground points including the ground strap going from the engine to the chassis. It takes a little time, but you will thank yourself later when you are not fighting serveral random electrical problems. When you clean the grounds use some dielectric grease to keep the weather out. Remove all of the fuses and relays and clean them as well. Scotchbrite works well.

If after that the car still does not start check for the injectors opening. I am assuming you checked the fuel pressure with a gauge and it is holding the prpoer pressure even after the fuel pump stops running. Pressure should reman high after the key is shut off for a long time. An immediate leak down suggests a bad regulator or damper.

Have someone turn the engine over while you hold a stethoscope or screw driver to one of the injectors. You should hear a click. No click the injectors are not opening and the car will never start. You need then to trace the signal from the computer to the injectors. The injectors when the ignition is on has 12 volts running to them. The computer opens the injectors all at once by grounding them. Find the ground side one injector and try touching the ground side to the block - do you hear a click? On an 84 do not worry so much about a dead computer as they rarely fail.

You have spark and the car fires so I would not waste anymore time on the ingnition system.

Good Luck
Dan the Pod Guy

w3lfd

Ok here's the latest :

Fuel pressure at the rail : with regulators connected to vacuum = 28
regulators disco = 35 'ish

Gonna go look for that wire right now. The only thing that is hooked to + atm is the main harness connector. I sure hope this is the problem!

EDIT: oops... Memory is a fickle thing.... The secondary accessory wire is indeed connected.

John Struthers

My God!
I've been lying - permitted under some circumstances - all these years...
There is a ground I could have missed
Thanks Herr Riffle for the ( somewhat late) enlightenment.

macreel

w3lfd... get a noid light on the injector connectors.
(injectors need good ground).

What's your fuel delivery volume? min. spec.=1,150 cc in 30 sec


G'luck

w3lfd

noid light? For some reason that is not registering in my brain. Where can i get one for how much.

I really need to find out if I am getting signal to the injectors. At least then i can eliminate or determine that is the issue.

I have a feeling this is gonna be a time consuming project. Though well worth it, I'm sure.

w3lfd

Noid light... Just ordered one. Just what I needed.

John Struthers

Wally aand others have the pin ut test procedures and readings in the archives

w3lfd

So here is where I am at the moment on this: Tried the jumper, no dice. Used the noid light, no light. Looks like it's go over all of the grounds and wiring time.

w3lfd

Okay, here's the update. Checked all of the electrical wiring so far. Everything seems good to go EXCEPT...

15 from Ignition control unit to the positive side of the coil is seeing resistance to ground.

I'm not sure if this is correct so I will explain in detail and hopefully someone will have an answer for me.

With the ignition off, battery ground disconnected, 15 wire disconnected from coil, harness disconnected from ignition control unit and ecu, i get about 500 ohms of resistance when testing between the coil end of the 15 wire and ground. Is this correct, because it doesn't seem to me that I should get anything but an open here?

Podguy

I would have to read out the wiring diagram to see if there is something else in the circuit. If not and you have isolated it to this circuit and have both ends disconnected, you can try running a bypass wire.

Before doing this check the diagram to see what else is in the circuit.

I have a Fox and Hound. This is a tone generator. It is great for tracing out wires and possible shorts. I believe Eastwood has one that is specifically designed for cars. You connect it to the suspect wire and then run the reciever along the out side of the cable until the tone stops. Where the tone stops is the break or grounding of the wire.

One common source of trouble is the front engine wiring harness that runs by the water pump and to the right side of the engine well. Heat and age causes deterioration inside the harness and some of the wires can get crossed. I took one apart recently and was mystified as to why the car still ran. The only thing I could figure is the corrosion on the wires was oferring enough insulation to prevent shorts.

Good luck,

Dan the Pod Guy.

w3lfd

Thanks, i'll need to check out the option of the "Fox and hound". Meanwhile I am going to trace the wire in the wiring diagrams. 15 is the switched power to the car, so I am going to need to physically follow the wire to it's origin (I'm guessing the relay panel or ignition switch) and get it disconnected to make sure I'm not chasing some other grounded component in the system.