Bad EFI computer? no spark - no codes UPDATE

[Recko555]

Mark,
You can try my spare A9P cpu if you need too. The cpu makes 1 or 2 error codes (that is why it is my spare) come up because of an internal ground, but it will run the engine just fine. Let me know.
Gabe

 

[Phoenix0783]

i was having a similar problem on the bronco deuce. it would only send a spark or start with the SPOUT out. I fiddled with and unhooked the mass air sensor connector, plugged it back in and it started working fine, so you could give that a shot.

 

[DirtDonk]

I'm not an EFI expert by any means, but if your relays are clicking (which would make the pump fire up too, I'm guessing?) then it sounds to me like your ignition switch is bad.

A "stuck" starter relay/solenoid can either be a bad relay (naturally), some feedback from somewhere through the "S" terminal, or the ignition switch. Which would better explain the fuel pump relay energizing.

Where do your relays get their energizing power from? Direct from the ignition switch? Or somewhere else?

Paul

 

[Ryan]

If your relays are clicking (which would make the pump fire up too) then it sounds to me like your ignition switch is bad.

A "stuck" starter relay/solenoid can either be a bad relay (naturally), some feedback from somewhere through the "S" terminal, or the ignition switch. Which would better explain the fuel pump relay energizing.

Where do your relays get their energizing power from? Direct from the ignition switch? Or somewhere else?

 

[Mark]

alright, back to work on my driver.
I had a great time on my week long trail run ( http://www.classicbroncos.com/forums/showthread.php?t=126747 ) trail rig ran great - I've got to push that thing more!

Now back to why my driver is not firing. I confirmed tonight that I am not getting spark from the coil. I've put in two coils - same result.
To make this determination I purchased a timing light, hooked it up to my number 1 cylinder plug wire, turn key to start - no flashy flash. Hooked it up to my coil wire, turn key - no flashy flash (I hooked the timing light up to my trail rig and got the flashy flash so I know my testing procedure is correct).
I placed the key in the run position and measured the voltage going to the tach at 12V. I did not measure the voltage going to the tach with the key in the start position (I'm a one man crew tonight what voltage should I expect?).

The coils I'm trying are stock Mustang coils from a '91 Mustang. One from BC's & one from the parts store.

I unplugged the coils and measured the resistance between the positive and negative terminals on the coil and measured 1.3 Ohms. Which according to this post ( http://www.classicbroncos.com/forums/showpost.php?p=777649&postcount=6 ) should be no higher than 1.0 Ohms.

Did I purchase two defunct coils that measure the same? Did I blow two coils? Should I try a "better" coil?

suggestions? ideas? I'm going to try a third coil I guess.

 

[Broncobowsher]

Your coil(s) are probably fine. that extra 0.3 ohms could simply be the resistance of the leads going to the meter. Not anything I would worry about.

What I am seeing is a trand, you are looking for spark from the coil. I am not seeing anything about checking what controls the coil. Is the ignition module and hall effect switch inside the distributer working correctly? That is what controls the coil.

By the way. They coil get a steady power (in the case of the EFI a steady 12V) all the time the ignition is on. The switching part of it comes from the control module making and breaking ground, just like points did. So when the ignition is open (like points open) there is 12V on both terminals of the coil. The ignition will close the connection to charge the coil and when it opens the charge collapses on itself creating the spark. I think your problem lies in the pickup in the distributor or the ignition module on the side of it.

 

[Viperwolf1]

Mark,
I get .5 ohms on the primary side and 8K ohms on the secondary side. Make sure you have a good ground to the coil also or that will kill it.

 

[Mark]

Good info.
Tim, I'll check the TFI and the stator/pickup in the distributor.

Phil, How are you placing your leads when testing your ohms readings? I'm simply placing the probes across the coil connector spades (+ and - )

and as far as grounding the coil, is it grounded through mounting bolts?

 

[Viperwolf1]

Pos to neg is the primary side. Pos terminal to the high tension terminal is the secondary side. It could be grounded through the mounting bolts but there has to be clean bare metal to metal contact. I fried one by just bolting it on.

 

[Mark]

Well, at least I'm narrowing down possibilities. Put another new rebuilt distributor in - same results... no flashy flash from the timing light when hooked up to the coil wire.
Coil is grounded well.
Bad relay maybe, short in the wiring maybe, ... Me and my multimeter are going to get a workout this coming weekend.
No way it could be the computer?

 

[Broncobowsher]

Unplug the computer and crank the engine, look for spark.
Have you checked power going to the module?

 

[Mark]

Well, I unplugged the computer and now I am getting spark.
I'm betting there is a short in it.
Going to locate a fresh computer and try again.

Getting closer and closer. It's inevitable that it will live.

 

[Mark]

Take the brown wire off. I had some problems starting with Ryan's harness and the brown wire connected. Try this before you change the solenoid cause I think it's ok.

Phil, you were right about that brown wire.
She purrs like a kitten.
WooHoo I'll post some pics and update my install in a new thread.

 

[Viperwolf1]

Congrats on getting it up and running Mark.