BlackBourbon
1/2 ton status
Buddys truck, 87 TBI. No injector spray when cranking but if you give it some fuel to start. both injectors spray fine. idles, drives, etc. just wont crank up again once shut off because lack of fuel for start
CK5
Register an account today to become a member! Once signed in, you'll be able to participate on this site by adding your own topics and posts, as well as connect with other members.
TBI pulse problems
- Thread starter BlackBourbon
- Start date
Have you checked for any codes?
If it is not getting fuel when cranking check the wire from ECM terminal C9 purple white wire and make sure it is getting 12 volts while cranking. Should be 0 when key on. 12+ volts when cranking.
If it is not getting fuel when cranking check the wire from ECM terminal C9 purple white wire and make sure it is getting 12 volts while cranking. Should be 0 when key on. 12+ volts when cranking.
New ignition module cured that same problem for me.
4xcrazy
3/4 ton status
did a search on this issue, as this is what i am finding is going wrong with my '89 TBI, it just quit last night, stopped at a stoplight, it shut off, i hit the key, cranked a couple revs, then fired right up, shut off again after a few revs, i did this 3 times while at the light, the light turned green, it fired, i hit the gas and ran.
It drove fine for the next mile, then just shut down again and will not refire at all.
Towstrap it the rest of the 3/4 mile home, look at it today,it fires with ether, no injector activity though, all fuses are fine, no apparent sign of exposed, or damaged wires.
This is a new issue for me, usually i dig through everything and troubleshoot, however, with the recent move from Phoenix to here, i don't have everything here with me, like spare electronic parts, not thrilled that i left those behind in storage out there.
anymore ideas on this matter? what all DOES control the injector timing?
It drove fine for the next mile, then just shut down again and will not refire at all.
Towstrap it the rest of the 3/4 mile home, look at it today,it fires with ether, no injector activity though, all fuses are fine, no apparent sign of exposed, or damaged wires.
This is a new issue for me, usually i dig through everything and troubleshoot, however, with the recent move from Phoenix to here, i don't have everything here with me, like spare electronic parts, not thrilled that i left those behind in storage out there.
anymore ideas on this matter? what all DOES control the injector timing?
Does it have spark? If not, that is also your fuel problem. When the EST goes out or is faulty you will not get any injector spray.
4xcrazy
3/4 ton status
Yes, it has spark, why i mentioned it fired with the ether 
i was just chatting with 4x4high through PM's, gonna remove the ignition module and see about having it tested.
Main question really was what all, or exactly, controls the injectors pulses, as i wasn't 100% sure on that.
Will update for further future informative useage when i finger this deal out 
i was just chatting with 4x4high through PM's, gonna remove the ignition module and see about having it tested.
Main question really was what all, or exactly, controls the injectors pulses, as i wasn't 100% sure on that.
Will update for further future informative useage when i finger this deal out
dave w
1/2 ton status
Troubleshooting this problem is not always easy.
What I would do.
Check for Fuel & Spark.
Lots of ways to check for fuel and spark. Sometimes I have to be creative to check fuel and spark. Most times I'm all by myself and I don't have any tools. Below are some examples of my more creative ways to check for fuel and spark.
Check for Fuel.
Paper Towel Method - Unplug the ignition coil wires to prevent the engine from starting. Remove air cleaner from TBI. Stuff clean / dry paper towels under each injector. Try starting the engine for about 5~10 seconds (I know the engine won't start because the ignition coil wires are unplugged). Now remove the paper towels from under the injectors. If both paper towels are wet and smell like gas, then it is likely the injectors are working and fuel pump is working. A word of caution, don't let the engine suck in the paper towels when doing this "check for fuel test". LEAVE THE THROTTLE CLOSED!!!
Check for Spark
Jumper Cable Method - Make sure the ignition coil wires are plugged in, if you unplugged the ignition coil wires in the Paper Towel check for fuel method described above. Basically it is dam near impossible to check for spark if you are trouble shooting by yourself? What I do that works for me when I am by myself to check for spark. I get a spark plug (any type spark plug will do - new or used), maybe I've even walked a fair distance to a store to buy just one spark plug because I didn't have any tools.
Remove the spark plug looking coil wire from the coil. Remove the longest spark plug wire from the distributor cap and spark plug. Plug one end of the longest spark plug wire to the ignition coil terminal (that normally goes to the distributor), and the other end to the spark plug. Usually the longest spark plug wire is long enough to position the spark plug somewhere that you can see if the spark plug "Sparks" when trying to start the engine. Now comes the jumper cable. The spark plug must be grounded to spark. I connect one end of the negative jumper cable to the spark plug, then I connect the other end of the negative jumper cable to the negative of the battery. Put both positive jumper cable ends in a safe place. A word of caution, don't hold the metal part of the the test spark plug when cranking the engine!!!!
So which is it, no spark or no fuel?
dave w
What I would do.
Check for Fuel & Spark.
Lots of ways to check for fuel and spark. Sometimes I have to be creative to check fuel and spark. Most times I'm all by myself and I don't have any tools. Below are some examples of my more creative ways to check for fuel and spark.
Check for Fuel.
Paper Towel Method - Unplug the ignition coil wires to prevent the engine from starting. Remove air cleaner from TBI. Stuff clean / dry paper towels under each injector. Try starting the engine for about 5~10 seconds (I know the engine won't start because the ignition coil wires are unplugged). Now remove the paper towels from under the injectors. If both paper towels are wet and smell like gas, then it is likely the injectors are working and fuel pump is working. A word of caution, don't let the engine suck in the paper towels when doing this "check for fuel test". LEAVE THE THROTTLE CLOSED!!!
Check for Spark
Jumper Cable Method - Make sure the ignition coil wires are plugged in, if you unplugged the ignition coil wires in the Paper Towel check for fuel method described above. Basically it is dam near impossible to check for spark if you are trouble shooting by yourself? What I do that works for me when I am by myself to check for spark. I get a spark plug (any type spark plug will do - new or used), maybe I've even walked a fair distance to a store to buy just one spark plug because I didn't have any tools.
Remove the spark plug looking coil wire from the coil. Remove the longest spark plug wire from the distributor cap and spark plug. Plug one end of the longest spark plug wire to the ignition coil terminal (that normally goes to the distributor), and the other end to the spark plug. Usually the longest spark plug wire is long enough to position the spark plug somewhere that you can see if the spark plug "Sparks" when trying to start the engine. Now comes the jumper cable. The spark plug must be grounded to spark. I connect one end of the negative jumper cable to the spark plug, then I connect the other end of the negative jumper cable to the negative of the battery. Put both positive jumper cable ends in a safe place. A word of caution, don't hold the metal part of the the test spark plug when cranking the engine!!!!So which is it, no spark or no fuel?
dave w
4xcrazy
3/4 ton status
i already know it's getting spark, that has been determined with a simple spray of ether down the intake, it fires right up, it's not getting fuel, but it's not a pump issue either, that is brand new, and i can hear it running when the key is on. There is absolutely NO injector activity though, no drips, dribbles, nothing, like it's out of gas completely, but i know there;s gas in there
I just went and had the ignition control module tested, (several times) and it never once read to be bad. According to what i read about the electronic spark control module, it didn't say anything about controlling injector pulse, all it said it does is controls spark timing and whatnot from readings determined by the knock sensor. i dunno,,,
Guess the next check is to noide the injectors, hope those aren't bad, they're only about a year old
I just went and had the ignition control module tested, (several times) and it never once read to be bad. According to what i read about the electronic spark control module, it didn't say anything about controlling injector pulse, all it said it does is controls spark timing and whatnot from readings determined by the knock sensor. i dunno,,,
Guess the next check is to noide the injectors, hope those aren't bad, they're only about a year old
dave w
1/2 ton status
Sometimes I put more information into a reply than necessary, to help other readers learn or look at a problem in a different way.
What I would do if I had "No Fuel" from the injectors not spraying fuel.
1. I agree a Noid Light Check is the next step. If the Noid Light failed to flash, I would check to make sure the injector connectors have battery voltage with the ignition switch in the "On" & "Start" position. To make the injectors "Pulse" the ECM sends "Ground" pulses to the injectors. The ECM is looking for a battery voltage when engine is starting, from a wire on the starter solenoid start circuit. It could be the ECM injector circuit inside the ECM has failed, in which case the ECM needs to be replaced.
2. I know of a method, a very dangerous method to test the injectors!!! With the engine off. Remove the injector connectors. Hot wire 12 volts to one of the injector terminals and hot wire ground to the other injector terminal. Send 12 volts to the fuel pump from the "fuel pump prime wire" for a few seconds. The injector should spray lots of fuel everywhere!!!! Keep electrical sparks from causing a fire with all the fuel vapor present!
dave w
What I would do if I had "No Fuel" from the injectors not spraying fuel.
1. I agree a Noid Light Check is the next step. If the Noid Light failed to flash, I would check to make sure the injector connectors have battery voltage with the ignition switch in the "On" & "Start" position. To make the injectors "Pulse" the ECM sends "Ground" pulses to the injectors. The ECM is looking for a battery voltage when engine is starting, from a wire on the starter solenoid start circuit. It could be the ECM injector circuit inside the ECM has failed, in which case the ECM needs to be replaced.
2. I know of a method, a very dangerous method to test the injectors!!! With the engine off. Remove the injector connectors. Hot wire 12 volts to one of the injector terminals and hot wire ground to the other injector terminal. Send 12 volts to the fuel pump from the "fuel pump prime wire" for a few seconds. The injector should spray lots of fuel everywhere!!!! Keep electrical sparks from causing a fire with all the fuel vapor present!
dave w
4xcrazy
3/4 ton status
Just did the noid light check, it flashed real quick once, paused a few revs flashed real fast once again, now nothing on both injector plugs.
I'm telling you, install a new module and i'll 99% guarantee your problem goes away. Worst case is the problem still exists and you now have a spare emergency back-up ignition module as they are a common failure point on any GM HEI ignition system. 
dave w
1/2 ton status
A few things I know about sharing / posting trouble shooting experiences.
1. The vehicle is not in my garage.
2. When the vehicle is not in my garage, I can't use my tools or my known good spare parts.
3. Not everyone I share my trouble shooting experiences with, will have the same skill sets as I, mechanical or electronic.
4. I know I can go down the wrong path in trouble shooting. Sometimes a problem looks to a fuel problem, but ends up an electronic solution.
5. Knowing what parts are fully functional, and which parts are suspect is the key to trouble shooting. I've learned to become creative with how I test suspect EFI parts.
At this point in time, I think the key to solving this "Fuel" problem is understanding what triggers the Noid light.
a. The ignition module sends a reference pulse / RPM signal to the ECM.
b. The ECM sends pulsing ground signals to the injectors.
c. With the ignition switch in the "ON" and "Start" positions the injectors will have 12 volts (battery power).
If the vehicle was in my garage, and the Noid Light tested failed ( failed includes just a few quick flashes and quits flashing). I would make sure the injectors are getting 12 volts with the ignition switch in the "ON" & "Start" position. Once I was satisfied the injectors are getting correct voltages. I would pour 4 ounces of gas down each throttle bore, and see how long the engine will run on vapors, usually about 15 ~ 30 seconds. My experience has taught me about 15 ~ 30 seconds of the engine running on vapors is an indication of a good ignition module. I would then install one of my known good ECM's.
dave w
1. The vehicle is not in my garage.
2. When the vehicle is not in my garage, I can't use my tools or my known good spare parts.
3. Not everyone I share my trouble shooting experiences with, will have the same skill sets as I, mechanical or electronic.
4. I know I can go down the wrong path in trouble shooting. Sometimes a problem looks to a fuel problem, but ends up an electronic solution.
5. Knowing what parts are fully functional, and which parts are suspect is the key to trouble shooting. I've learned to become creative with how I test suspect EFI parts.
At this point in time, I think the key to solving this "Fuel" problem is understanding what triggers the Noid light.
a. The ignition module sends a reference pulse / RPM signal to the ECM.
b. The ECM sends pulsing ground signals to the injectors.
c. With the ignition switch in the "ON" and "Start" positions the injectors will have 12 volts (battery power).
If the vehicle was in my garage, and the Noid Light tested failed ( failed includes just a few quick flashes and quits flashing). I would make sure the injectors are getting 12 volts with the ignition switch in the "ON" & "Start" position. Once I was satisfied the injectors are getting correct voltages. I would pour 4 ounces of gas down each throttle bore, and see how long the engine will run on vapors, usually about 15 ~ 30 seconds. My experience has taught me about 15 ~ 30 seconds of the engine running on vapors is an indication of a good ignition module. I would then install one of my known good ECM's.
dave w
4xcrazy
3/4 ton status
Scott, the problem i am having right at the moment with just replacing the ignition module, is i don't have the money for it, literally, flat broke.
I took it to a place and they did their little electronic testing on it, several times, it never glitched or anything saying it was bad, i don't know to what extent or what exactly that thing tests though, unknown if it knows or how it works, how the signal is processed for the injectors pulse pattern signal. This IS the original GM module, and if i had the cash for one, i would definately pick one up.
Something else i noticed, actually a few months ago, so this is not exactly new, so i know it ran with this going on, is when i try to check the CEL with the twoprong key, i get maybe 3 patterns of 12, fine, but then when it gets to a point where it should start telling me codes, the light starts flashing dimmer and dimmer until it won't show anymore. I took video of it doing this to show ya, it's still loading on Youtube now. Not sure what this deal is.
I looked around again for any wiring issues, moved the harness around a bit to see if something was shorting out or something, usually blows fuses when that happens though
I am not dismissing any info you guys are tossing out here, i really can only do so much at the moment with the financial situation the way it is. I am really just trying to sort through things with what tools, test equipment i do have to somewhat pinpoint WHAT should be replaced, without having to go through the dreaded, replace everything till it's fix thing alot of people do with these TBI systems.
I'm wondering about that little $7 pick-up coil inside the distributor, although the last time i had issues with that, i had no spark, but did have injector spray.
Here's the video i took with my phone, sorry it's sideways, guess i can't remember which way to hold the phone for video, it's also a dark video,,, it's dark outside :P
But what you see, is exactly what the light does, it just fades out to nothing as it flashes. I have never seen these things do this before.
http://www.youtube.com/watch?v=8uEwaB3TUfg
I took it to a place and they did their little electronic testing on it, several times, it never glitched or anything saying it was bad, i don't know to what extent or what exactly that thing tests though, unknown if it knows or how it works, how the signal is processed for the injectors pulse pattern signal. This IS the original GM module, and if i had the cash for one, i would definately pick one up.
Something else i noticed, actually a few months ago, so this is not exactly new, so i know it ran with this going on, is when i try to check the CEL with the twoprong key, i get maybe 3 patterns of 12, fine, but then when it gets to a point where it should start telling me codes, the light starts flashing dimmer and dimmer until it won't show anymore. I took video of it doing this to show ya, it's still loading on Youtube now. Not sure what this deal is.
I looked around again for any wiring issues, moved the harness around a bit to see if something was shorting out or something, usually blows fuses when that happens though
I am not dismissing any info you guys are tossing out here, i really can only do so much at the moment with the financial situation the way it is. I am really just trying to sort through things with what tools, test equipment i do have to somewhat pinpoint WHAT should be replaced, without having to go through the dreaded, replace everything till it's fix thing alot of people do with these TBI systems.
I'm wondering about that little $7 pick-up coil inside the distributor, although the last time i had issues with that, i had no spark, but did have injector spray.
Here's the video i took with my phone, sorry it's sideways, guess i can't remember which way to hold the phone for video, it's also a dark video,,, it's dark outside :P
But what you see, is exactly what the light does, it just fades out to nothing as it flashes. I have never seen these things do this before.
http://www.youtube.com/watch?v=8uEwaB3TUfg
dave w
1/2 ton status
To make the Check Engine Light flash, the ECM sends ground flashes / pulses to the light. When the ignition switch is on, 12 volts is sent to one of the wires for the CEL, the other wire going to the CEL is from the ECM.
Maybe, just maybe the ECM is bad. The ECM uses ground pulses to control the injectors, and ground pulses to control the CEL light. Strike one / Strike two for the ECM being the problem.
dave w
Maybe, just maybe the ECM is bad. The ECM uses ground pulses to control the injectors, and ground pulses to control the CEL light. Strike one / Strike two for the ECM being the problem.
dave w
X2I'm telling you, install a new module and i'll 99% guarantee your problem goes away. Worst case is the problem still exists and you now have a spare emergency back-up ignition module as they are a common failure point on any GM HEI ignition system.
4xcrazy
3/4 ton status
BTW, i'm not doubting you, as mentioned it's just a matter of funds right now, that i cannot afford, and especially if it turns out NOT to be the issue.
anyhoo, thanks for the assistance, i'll let ya know what's up as soon as i change it out, i'm in the process of locating a good known used one for now to test. Sucks as i KNOW i had another laying around somewhere, just not sure if i left in Poenix or not....
Thanks
4xcrazy
3/4 ton status
WELL,,, today i received the part from Paul (Pauly383) from a couple of distributors i left behind there in Phoenix, the ignition module, he sent me two, just in case one didn't work, or to make absolute sure type of deal.
Installed the one that was the obvious replacement, not a GM unit, tried cranking the truck over, it was slow, but then again, it's cold as my EX outside now, didn't fire, was gettin alittle down about this, so i decided to hit it with ether. It fired right up and stayed running.
So far, all is good.
AGAIN, Scott, i was not doubting you with what you told me, just didn't have the part in hand or the money to get one right away.
Ignition control module was the apparent reason for no fuel injector pulse in this problem
Installed the one that was the obvious replacement, not a GM unit, tried cranking the truck over, it was slow, but then again, it's cold as my EX outside now, didn't fire, was gettin alittle down about this, so i decided to hit it with ether. It fired right up and stayed running.
So far, all is good.
AGAIN, Scott, i was not doubting you with what you told me, just didn't have the part in hand or the money to get one right away.
Ignition control module was the apparent reason for no fuel injector pulse in this problem
Last edited:
Glad it's fixed. Now when you get some extra cash I would buy another to keep in the rig as an emergency back-up as these are a common failure point and at about 5 minutes to fix IF you have a spare it's worth it to not be stranded somewhere.
4xcrazy
3/4 ton status
Yeah, i plan on buying a new one for it when the money allows, also was looking at the throttle body unit while it was running, i don't like the way the fuel is being thrown around in the bores, seems the passenger side, acts like there's too much pressure or something, the fuel sprays out in a nice cone shape, but now and then you can see little splashes of fuel being thrown around, like it hits the butterfly and bounces back up or something. Also alittle accumulating, in the angled part that is part of the pod, center stand or whatever, then runs down when a droplet heavy enough forms.
Think with over 250k miles on this TBI unit, i may just spring for a brand new unit down the road. No major leaks or any major droplets, just now and then, and the splashing the one side seems to do. These injectors are installed correctly and are only about a year old, brand new units from Napa, OEM replacements.
But again, Scott, thanks for your advice, a big thanks for Pauly for coming through for me on shipping those parts.
Think with over 250k miles on this TBI unit, i may just spring for a brand new unit down the road. No major leaks or any major droplets, just now and then, and the splashing the one side seems to do. These injectors are installed correctly and are only about a year old, brand new units from Napa, OEM replacements.
But again, Scott, thanks for your advice, a big thanks for Pauly for coming through for me on shipping those parts.
4xcrazy
3/4 ton status
well that was quick, dead again, acting the exact same way again, just shuts down, no warning, nothing. Haven't checked yet if it's the injectors again, but suspecting the same deal.
$500 for this Suburban right now
$500 for this Suburban right now
