No Spark or Fuel During Engine Crank

[Posi]

This is a tach filter found about 6" from the ecm




I removed the jacket from the tach filter, resistors look to be 20k, 10k, and 1k from what I can tell by the bands. A chip, and possibly a zero resister, I'm not sure what the last piece is.

 

[Posi]

You will find B5 in the smaller of the two connectors.

 

[Lumpy Grits]

I'll bet you'll find that unknown part to be some type of voltage regulator/limiter.
Not uncommon in small DC circuit parts like that.
LG

 

[thundley57]

I don't think Troy is sending you on a buying spree, but he isn't trying to save you money either by suggesting the problem “could” be the tach filter "or" ecm without offering any diagnostic tests to confirm it.


When I diagnosed my tach filter I preformed the same test I suggested to you (key on, touching power to the white coil wire). My injectors did not spray, (yours did), the non-spray told me my the tach filter or the ecm was faulty. I next touched power to B5 pin on the ecm and the injectors sprayed fuel. This told me the tach filter was bad. I replaced it and the engine ran as it should.


As I previously mentioned the tach filter is a circuit board and it's possible some components in the filter are working, and others are not so lets do the next test.


Compare the injector spray from your previous test (when you touched the coil white wire with the test light) to the injector spray when you touch B5 pin on the ecm. You will need a helper to touch pin B5 while you inspect the spray. Is the volume the same or different from when you tested the white coil wire?
Key is on with both tests, test light connected to the + battery post. Same as the white coil wire, just touch the B5 pin on and off.


Also, do you mean 12.6 battery voltage? Your posting 13.6, unless it just came off a charger.

Posi, so B5 is the smaller of the two connectors to the ECM correct? Are they labeled? When you say touch B5 with the test light is this with the connector disconnected and if so, am I tapping the connector side or the ECM side? I'm at work and just want to clarify this before I start working on it possibly this evening since there is a 3 hour time difference between us. To answer your question in regards to my battery voltage, yes it was 13.6 but that was with a 2 amp charger attached to it. Thanks a million for hanging with me!

 

[007]

With all sincerest apologies for the pain the OP is going through...this has STICKY written all over it... GREAT thread...

 

[Lumpy Grits]

110%

LG

 

[Posi]

First, I think your doing a good job of testing and relaying info back to the forum.


It's the smaller of the two connectors
Their labeled, but hard to see.
Use the diagram I posted to ID where B5 and the purple w/white tracer is located.
The small connector has side A and B
The B side should only have 7 wires going to it
Leave the connector plug connected.
Attach one end of the test light to the + side of battery
Probe the back side of the connector at B5 (purple w/white wire) terminal.

 

[thundley57]

First, I think your doing a good job of testing and relaying info back to the forum.


It's the smaller of the two connectors
Their labeled, but hard to see.
Use the diagram I posted to ID where B5 and the purple w/white tracer is located.
The small connector has side A and B
The B side should only have 7 wires going to it
Leave the connector plug connected.
Attach one end of the test light to the + side of battery
Probe the back side of the connector at B5 (purple w/white wire) terminal.

Posi, my B5 connector is a small purple wire with no tracer. The purple wire with white trace is in the A11 position. I didn't do the tap test on either one of them yet in fear of frying the ECM. I'd post a picture but this site won't let me for some reason.

 

[007]

Posi, my B5 connector is a small purple wire with no tracer. The purple wire with white trace is in the A11 position. I didn't do the tap test on either one of them yet in fear of frying the ECM. I'd post a picture but this site won't let me for some reason.

I urge you to get Tapatalk on your smartphone...assuming you have one. It's the BEST / EASIEST way to post pictures. You can post with pictures right under your Jeep.


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[thundley57]

Thanks 007


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[Posi]

The chart is from a GM TBI which howell copied. I'm sure they just used a purple wire without tracer while building the harness.

If your emc is 1227747 and B5 is clearly marked I would test it (B5 = EST high reference).

FYI, A11 is the MAP ground and should be a purple or black wire with no white tracer.

 

[Posi]

I had the distributor torn apart to change the centrifugal weights.

Could you double check the weights/springs and confirm their working as they should.

 

[thundley57]

The chart is from a GM TBI which howell copied. I'm sure they just used a purple wire without tracer while building the harness.

If your emc is 1227747 and B5 is clearly marked I would test it (B5 = EST high reference).

FYI, A11 is the MAP ground and should be a purple or black wire with no white tracer.

A11 is clearly purple w/white tracer and is a little thicker wire than the purple wire in B5. I do have the 1227747 ECM so I'm going to go ahead and test the B5 purple wire.

Could you double check the weights/springs and confirm their working as they should.

I removed the distributor again last week looking for any obvious problems, weights and springs were in working order. Re-checked the dist coil PU just to make sure, 590 ohms. Re-installed and set back to 8 deg BTDC.

 

[Posi]

I wasn't questioning the wires at A11 or B5. I was suggesting the GM chart colors won't necessary match the howell wiring harness. A solid purple wire at B5 on a howell harness is fine, more important is that you probe at the B5 pin.

 

[thundley57]

I wasn't questioning the wires at A11 or B5. I was suggesting the GM chart colors won't necessary match the howell wiring harness. A solid purple wire at B5 on a howell harness is fine, more important is that you probe at the B5 pin.

Ok thanks, will probe in the morning. Trying to get this thing fixed while remodeling a kitchen at the same time and the wife is questioning my priorities.

I'm guessing that what I'm hoping to see is the injector spray to be less when I probe B5 than when I probe the white wire indicating a faulty tach filter is that correct?



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[thundley57]

I'm hoping these videos will upload. The first one is the injector operation while tapping the white tach reference wire.

https://youtu.be/CfT05g9BzeA

This next one is the injector operation while tapping the B5 terminal on the small ECM connector.

https://youtu.be/FtbUMIawHNo

I don't see any difference in the volume of fuel being injected but if you guys see something different please let me know. You'll notice paper towels stuffed down the throttle body below the injectors. I put these in just to keep more raw fuel from traveling to the cylinders during the test.

Here's a video of my spark test to show the amount of spark I'm getting from the coil while cranking the engine.

https://youtu.be/CfGObTcvWRY


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[Torxhead]

Thanks for sending in those videos, you seem to have a good spark there. The two videos of injector testing do look pretty much the same to me also. Then the ecm has its way of firing them also, but either the ecm or tach filter can still be the issue. Refering to post #113, where you installed the distributor, do you think it is in an accurate position to fire the engine and keep it running? I know when the t.b.i. first fires it has a very rich fuel mixture also.

 

[Posi]

Good video info.
There is no timing control from the ECM until the rpms get above 400, that is read from the white wire to pin B5 of the ecm.
However, the videos shows the fuel spray consistent between the white wire and B5 pin.
Still a chance the tach filter isn't fully working as it should.
But I'm not ready to go there yet without checking, and double checking a few things.

Re-check for any engine codes

Distributor set on the "compression" stroke?
How many vacuum lines do you have going to the TB and intake, are there any T's?

Inspect all vacuum lines for leaks
When the engine tried to start last did you apply throttle to keep it going?
What is your base TPS set at?

Do only test 3, part 1, post your findings.

Part 3 -How to Test the Throttle Position Sensor (GM 4.3L, 5.0L, 5.7L)

 

[thundley57]

Good video info.
There is no timing control from the ECM until the rpms get above 400, that is read from the white wire to pin B5 of the ecm.
However, the videos shows the fuel spray consistent between the white wire and B5 pin.
Still a chance the tach filter isn't fully working as it should.
But I'm not ready to go there yet without checking, and double checking a few things.

Re-check for any engine codes

Distributor set on the "compression" stroke?
How many vacuum lines do you have going to the TB and intake, are there any T's?

Inspect all vacuum lines for leaks
When the engine tried to start last did you apply throttle to keep it going?
What is your base TPS set at?

Do only test 3, part 1, post your findings.

Part 3 -How to Test the Throttle Position Sensor (GM 4.3L, 5.0L, 5.7L)

Will do, it may take me a day or two to post the results. One question; does my Howell supplied ECM truly control timing? I know the original did because there was a connector you had to disconnect before setting the base timing which isn't true with the Howell supplied ECM. I also seem to remember reading somewhere that the upgrade removes the ability for the ECM to control timing, am I wrong? Once again Posi, Torxhead, thanks for hanging with me!

 

[Posi]

Howell standard kits do not control timing unless you ask them to include it.....for extra cash.

You don't have ecm timing control setup, if you did you wouldn't have a tach filter, working distributor weights, stock coil. However, you could do it yourself ecm timing control it's not real hard to do.

If your not running timing control with your FI your only getting half the benefit of going FI.