ANYTHING else that could be causing this no spark issue?? WTF


misterW

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1991 3.0 isn't getting a spark as tested at individual plugs and at the coil.

The wire that carries the pulse signal FROM the distributor to the ignition control module seems to be working just fine -- I get a flashing LED light whenever the vehicle is cranked over.

The wire that carries the pulse signal from the ignition control module TO the coil does not seem to be working -- I don't get a pulse signal from this wire when the vehicle is cranked. Seems like an ignition control module problem.

To make sure that the wire from ignition control module to coil wasn't grounded out somewhere, I put current on one end where it plugs to ICM and a test light on the other where it plugs to coil and it lit up just fine. So that wire seems to be OK.

The individual wire terminals in the clip that goes to the ignition control module all look in great shape. I've taken them out and examined them.

So, pulse signal goes to the ignition control module, but not from the module to the coil. Seems like the ignition control module is messed up, right? But I just replaced it, and I have the same issue!

What could I be overlooking?
 


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misterW

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Tomorrow I am going to verify that the ground that is going to the ICM isn't disappearing when the vehicle is cranked....other than that, and trying ANOTHER module, not sure where to go.
 

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Can the SPOUT in or IDM out terminals of the ignition control module be in any way responsible for a no spark condition? The diagnostics that I have been using haven't referenced them and it is my understanding (please correct me if I am wrong) that they are used to set the timing for the fuel injection and do not control the actual spark. Is it possible that if one of these were accidentally grounded somewhere it could cause problems with the spark somehow? Just trying to make sure that I've covered all possibilities.

Also, just to aid my understanding: is the SPOUT in essentially the same as the PIP in that comes from the distributor? And the IDM out similar to the signal that gets sent to the coil? What is the signal path that controls the fuel injection?
 

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RonD

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There were 4 TFI modules, grey and black colors ID the two different types that have different wiring and are not interchangeable.
Grey modules calculate Dwell and Black modules do not, they rely on computer to do both dwell and "vacuum advance" calculations

There were grey and black that mounted on side of distributor and grey and black that mounted on rad support, remote mount
3.0l used Remote mount

Good read here on those 4 TFI modules: http://www.myo-p.com/Ford-EEC/EEC Help files/Files/TFI_grey_or_black.html

SPOUT is the "vacuum advance" signal from computer to ICM, it is disabled to set base spark timing, then enabled for better spark response when driving, unplug the SPOUT "jumper"
It is not needed for engine to run, just makes it run better

IDM signal, on the black color modules only, is a monitor and computers compare that to PIP signal AND any SPOUT changes computer may have "suggested"
Computer will set a code if its unplugged or shorted but module would still work to start engine

PIP is the timing pulse from distributor's Hall Effect sensor to ICM, and it is also passed on to computer so it can time injectors and calculate "vacuum advance"

Remove the negative wire from the Coil, see if it pulses Ground signal without being connected to coil

With coil wires connected, the coil negative wire, pin 2 on the TFI module plug, should show 12volts with key on, battery voltage
An ignition coil has very low OHMs/resistance, usually under 1.2 ohms and the coil + should get battery voltage with key on, so that voltage should pass thru the coil and show up at #2 on the module plug
Crank engine while testing voltage on #2 wire, voltage should drop to 9-10volts from starter motors amp draw, but NOT drop to 0volts, if so there is an ignition wiring issue, you are losing voltage in START but have voltage in RUN positions
 
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misterW

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just did some testing prior to your message and am on to something because with idm and spout disconnected, I DO get a spark.
 

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That is odd neither of those wires should effect startup/cranking spark
 

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With only SPOUT disconnected, I get a spark. With SPOUT connected, I don't. When cranked, SPOUT shows a continuous ground on LED light instead of a pulse. My assumption is that the SPOUT wire is grounded somewhere along it's route to the ICM? Not sure why that would cause the problem. Especially because I was getting a continuous pulse with the PIP signal. I guess I could see the PIP signal being messed up if there was a grounded SPOUT wire (doesn't the pulse wire that comes out of distributor split and go to ICM and fuel injection computer?) but I was getting continuous PIP when cranking just not the pulse going to the coil (until SPOUT was unplugged).
 

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here's a question: the truck can run without the SPOUT hooked up. but can it run with a grounded SPOUT?
 

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Wouldn't know, never tried grounding the SPOUT wire, but from your tests I guess not.

SPOUT wire is connected to pin 36 on the computer, you could disconnect computer harness connector and see if the SPOUT wire itself is grounded some where or if its grounded inside the computer, if so pop the top on computer and have a look inside

There are 3 blue capacitors inside that do leak and fail, causing odd running issues, they can be replaced for under $5

Have a look here at what computer should look like inside: http://www.auto-diagnostics.info/ford_eec_iv


EEC-IV repair info here: http://support.moates.net/capacitor-repair-ford-a9l-ecm/
 

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I should be able to start without the SPOUT hooked up, though, right? I don't seem to be able to. The SPOUT wire is not grounded between the ICM and the computer. Checked for that and for continuity. Wire seems fine. And the PIP signal gets to the computer, checked that too. Maybe the problem is in the computer itself, because I should get a pulse on the SPOUT wire, right?
 

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Yes, spark will work without SPOUT wire connected

Try adding fuel manually to intake that tells you if you have good spark and if its happening at the right time, 50/50 test
If engine starts and then dies then yes either computer is not opening injectors or there is no fuel at the injectors(test for fuel pressure)
 

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I tested for fuel pressure at the valve initially before finding that I didn't have a spark and it was normal. Is there a way to test the actual injectors?
Also, just to make sure: when the vehicle is cranked, what should the SPOUT wire show (a pulse, right?) and what should the IDM wire show?
 

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Never tested SPOUT, but signal comes from computer not module

IDM is same as tachometer signal so a pulse from module, same as PIP(from distributor), and Coil(from module)

Just spray fuel into the intake and crank engine
If it starts and dies, and you have fuel pressure, then injectors are not opening, so computer issue
 

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Sprayed some fuel in and it started firing. So it does look computer issue. Can I just stick another computer in? These aren't the sort of computers that have to reprogrammed in any way, right?
 

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And after it started firing did you check fuel pressure?

Should squirt out at 30psi pressure once RPMs reached 400

You can use a 1991 Ranger 3.0l computer, needs to match Manual or Automatic transmission, 2wd or 4x4 doesn't matter

Also EGR or No EGR not sure what 1991 3.0l has
 


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