Injectors not firing?...Fixed

[readymix]

****Update at end****

Well here is the story. I removed my distro to change the pickup, but whne i reinstalled ti the truck will not start.

The timing is set correctly, but that does not even matter....The injectors are not firing. The fuel pump is coming on as i can hear it. It is not out of gas either.
I have checked all of the fuzes but still can figure it out.

One thing i am not sure of is a disconnected wire i just found last night. It is Brown with a Black or White tracer. Can't remember which right now. It is located right next to the EST connector. The one you unplug to set base timing. There is no where for it to plug in??? I know there is on my neighbors truck, What is different with mine. What else should i check?

 

[sandawgk5]

Hey check for spark. I had the same problem on my 87 350. If the ESC has gone bad and there is no spark then the computer will not let the injectors fire.

Ira

 

[readymix]

Thanks Ira, I just read up a little bit on ThirdGen. I replaced the Pick-Up coil but not the EST. Too expensive. I guess i need to remove it and have it tested.

 

[dyeager535]

I beleive the reference signal on the EFI setups is from the module directly to the ECM.

Thirdgen.org's technical article section has the '85/86 TPI wiring diagrams, I don't believe TBI differs in that regard.

Let's see if this works:

 

[sandawgk5]

That book is one of the best things I have for working on my truck. Brian I may have had my terminology wrong. The part that went bad on mine was the piece that has the two weather pack connectors on it that bolts inside the distributor I thought it was called the esc it is commonly reffered to as "The Module". That what was fubard on mine and Dyeager helped me with that also.

Ira

 

[readymix]

That is the EST. The crappy thing is that it was working fine 2 days ago. Now it is bad?? WTF. All i did was change the pick-up coil as it is cheap and looked a little corroded.
I have not even gone out to look at it yet because i think i will just get pissed off.

BTW: what book does all of those T/S charts come out of?

 

[sandawgk5]

It is the driveability and emissions GM service Manual. It is the same one that the dealerships use when you take it to them to work on. The guy I bought my K5 from gave me a complete set for 1987 Trucks Vans Suburbans and Blazers. I even have all of the wiring diagrams for 1987 R/V, S/T, and P vans.
With the modules I have heard that unless you buy the GM original parts it is kinda iffy how long they will last. My Niehoff one lasted only about 1 year and that was only about 3 months of actual driving time.

Ira

 

[dyeager535]

That particular one is the '88 camaro service manual. I haven't looked at an '87-91 C/K/R/V manual to see if they have the same sort of troubleshooting flow charts. The wiring diagram is a separate manual, but it is necessary to get the wire color for each circuit mentioned so you pick the right one to test.

Again, not fully up on TBI, but ESC on early TPI setups is a standalone part. Later on ESC was handled directly by the ECM, so no more module, I can't recall whether TBI has one or not. "Ignition module" is the correct term for what is under the cap. EST is electronic spark timing, ESC is electronic spark control. Ignition module only controls the timing during crank, (essentially) all other times are handled by the other components. (ECM and/or EST module)

 

[readymix]

How about this,
Is there any specifig goop i need to put under the module? I used Arctic Silver as it is the best heat transfer stuff i have ever used. It goes on all of my computers. I can't believe that it alone would cause the module to go bad.

Are they very sensitive to vibration? I don't remember dropping it or anything like that.

 

[sandawgk5]

I am not sure on the heat sink stuff I just used what came in the box with the module it did not seem to be anything special. And if they are mounted in an offroad truck I cannot believe they are that susceptable to shock.

Ira

 

[89GMCSuburban]

My ignition module went out three times so the truck would not start from the injectors not firing. ~$20 later, it was up and running. Since then, I replaced the entire distributor and haven't had a problem.

 

[readymix]

True about the shock thing. I will go over the wiring agian as i might have put a connector on wrong. My neighbor is the guy who removed my distro when i told him to swap the two out, (put mine in his truck) then we found out what was wrong with his and fixed it without ever using mine. So i cleaned mine up, put in the new pick-up and reinstalled and now NO GO.....

While he was removing mine he broke the clips off of the weatherpack connectors to the EST. They might be just loose??

 

[clarkjw24]

My ignition module went out three times so the truck would not start from the injectors not firing. ~$20 later, it was up and running. Since then, I replaced the entire distributor and haven't had a problem.

Hey guys I'm still fighting with my tbi and just want to rule out the bad module. So if my injectors are spraying then the module should be good right?

 

[readymix]

Nope. That is where this whole thing started. The neighbors truck was running like crap so we were going to swap Distros (see my post above)

Turns out he had a bad
-Module
-Pick-up coil
-Reluctor (broke post)

Now it runs like my 2002 Avy

 

[89GMCSuburban]

Possibly, but to make double sure, you pull off the two screws, take it to auto zone and let them test it for free...

 

[readymix]

Possibly, but to make double sure, you pull off the two screws, take it to auto zone and let them test it for free...

I will do that tomorrow, definatly before i pull the distro again

 

[randy88k5]

This is from a thread I responded to a while ago...

I had a problem a while back, which all led to the ignition module. Code 42 IIRC. I got a new one, ran better, but still had an intermittent problem. Would sputter and die at a traffic light, or just generally run loud and stumble a lot. I ran through a bunch of tests, isolating different areas.

I had a hunch and borrowed a friends Snap-On scanner. I remember seeing something on the road test that didnt make sense. It was contradicting what everything elso told me. I looked at wiring schematics, and found that the only logical problem could have been faulty wiring or a bad computer. I tested resistance at a few wires I could get to, and took the gamble with the computer. Got a brand new GM TBI comp. Fixed it good as new. Re-used old PROM.

Just a thought.
Good luck. Ill try my best to help out...

 

[dyeager535]

Using a real GM module is the first step to getting one that actually works, and although I'd recommend using whatever comes with the module, I'd have to assume it's just a high quality heat sink goop (not some specific GM formulation) that will stand up to some serious heat, which makes sense. Typically they say use "xxxxx part number, or equivalent" but no idea how you know the equivalent if it's not mentioned on/in the packaging of whatever you want to use.

The pins at the ECM could even be corroded, the service manual doesn't even mention that as a cause, but that would indicate a failed ECM when in fact it's a simple connection issue.

From what I've seen of my 15'ish year old ignition stuff, a good in-depth tuneup with GM ignition parts can't possibly hurt. At least inspecting all the electrical connections, (including plug wire to cap terminals) cleaning any that you can, making sure the pickup coil wires aren't as bad as mine are, etc. My truck idles better after going through and making sure everything was in tip top shape. (short of the pickup coil I still need to replace)

 

[readymix]

Well i went to Twin City (a local place that i use), I would rather walk than go into an Auto Zone
The EST tested good. Now i am off to check if i can force fire the injectors through the module. If so then the pick-up coil is bad. Wish me luck.

 

[readymix]

Turns out it was the main shaft. THe magnetism was so weak that it would not fire the pick-up coil.

Thanks for all the help