95 Park Ave Ultra Injectors not firing!

[Donb1955]

Have had ongoing problems with not starting to running very rough to dying. Has been parked for a about a year with fuel drained. Was running so bad it would hesitate surge or die and restart on it’s own while cruising on highway. Have replaced battery, ignition control module, plugs, wires, crankshaft sensor, camshaft sensor (including wires that had fried), mass air sensor with no improvement. Replaced fuel filter, Removed & cleaned fuel tank (wasn’t very dirty), replaced fuel pump & fuel pump relay. After replacing all the fuel stuff it wouldn’t even start. Fuel pressure checked good so I used some starting fluid and it ran as long as I was spraying. Put a noid light on all injectors but no light at all. This is driving me nuts but I will not stop until I figure this out. Before I changed all of the fuel components 2 different mechanics were stumped as well with all the rough running thing. I was looking at the schematics and see that the PCM is next in line but the parts store can’t check it and it’s about $130 and (not returnable). Read some other forums about the injectors and it was suggested that the voltage be checked at the injectors. The voltage on both sides with key on should read 12V. With engine cranking one side should drop to about 8V. Wierd thing is both sides drop to about 9V. My understanding is that the PCM controls this. Does anyone have any suggestions?

[HotZ28]

If the car was parked for a year, the injectors still contain fuel. More than likely the injectors have a tarnish build up and have seized. Pull each injector and spray carb cleaner in them. You should be able to here/feel the coil energize with 12v applied while tapping the coil on a metallic surface. Been there, done that.

[autojoe]

key on engine off you should have close to b+ on power side of injectors.......unless b+ is very low....if so charge battery......if then still low go back through wire till you get b+ maybe wiring problem.then after getting b+ on power side the noid light does not flash and stays on steady with no flicker then would have to troubleshoot why.do you have wiring/pcm schematics?let me know.what size engine?

[Donb1955]

I will clean injectors and let you know, thanks HOTZ28. Autojoe, I have 12V on both sides with key on. The info I have says the voltage drops on one side while starting because the PCM actually grounds the one side for a split second which is what activates the injector. It may be dropping on both sides because the injectors are stuck causing resistance. I will find out soon enough! Thanks

[Blue Bowtie]

Despite the condition of the injector pintle, the injector solenoid should receive a pulse (momentary firing) from the ECM. In other words, a stuck/clogged/mechanically damaged injector will still look the same from the perspective of the ECM. So long as the ECM sees something above 8Ω it will tolerate the load. 12-16Ω is preferable, measured cold.

Since your original post indicated that a solenoid indicator light does not "fire" under test, I would suspect the ECM is not providing pulses. This may be due to the ECM, or may be the result of a lack of input information, such as the CKP or CMP sensor, or a problem in the ICM (under the coil packs), or any of the associated wiring. The fuel control signal to the ECM is at Pin D on the ICM (a purple/white wire), which is also Pin C3 on the bulkhead connector. Loss of this trigger signal to the ECM will prevent any injector pulses.

Your source of information is not completely correct. A typical voltmeter MIGHT read 8-9VDC at the injector (or might not) when it is operating due to the RMS averaging of the meter, but the actual voltage is 12DC and duty cycled based upon the ECM output signals. The waveform would look something like this:

__________|-|__________________|-|________________|-|______

Fuel Injector ^ Pulse

If there are no injector output pulses (generally a few mS at start or idle) the injector has no chance to perform its job. If there are injector pulses and no fuel is being administered, you need to verify at least 37 PSIG rail pressure.

If that is correct, you can possibly avoid removing the injectors by attempting to statically operate one injector at a time while in place. Apply 12VDC to an injector via a test plug or carefully placed alligator clips. Operate the injector for only a few seconds before allowing it to close and cool for a few seconds since there may be no fuel flowing through it to cool the solenoid. Make sure the fuel pump is running and/or fuel rails are charged and you have a gauge installed to monitor pressure drop. If fuel flows you should be able to detect the pulse or pressure drop on the gauge.

If that is unsuccessful, you can remove the injectors, inspect the inlet screens, apply 45 PSIG reverse air pressure and manually power the injector (about a 10% duty cycle to allow cooling since they are saturated type injectors), and see if you can establish flow through them.

Still, it seems that you have a problem on the control side since the test light does not operate, so verify that first.