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 Page 1 of 3 123
Username Post: 89 Blazer K5 TBI no spark no fuel        (Topic#348995)
89K5Shane 
Poster
Posts: 33

Reg: 01-03-18
01-03-18 03:16 PM - Post#2719898    

I am new to this forum and am totally stuck with this problem.
The vehicle ran great and shut down and was towed home with no fuel no spark. I changed the ignition module and pick up coil and it fired right up and ran great. It died a week later in the driveway and once again no spark no fuel. The ignition module tested bad at Autozone so I replaced it. It fired right up and died an hour later.
To date I have replaced the coil, pickup coil, ignition module, cap and rotor. I have tested the pink wire on the grey connector at the coil and have steady 12v also 12v leaving on the pink to the module but I do not get the signal coming back to the coil from the module. I have tested the coil by tapping a ground to the white wire and get spark from the coil. I have also jumped the injectors and they work. It is my understanding that if I have steady voltage to the pink feeding the coil then the problem is downstream from there leaving the pickup coil and ignition module. I took the wires off connecting the coil to the mod and tested with an ohm meter while pulling and bending and no opens are there. I have replaced the mod 4 times and pickup coil twice and am getting fuel now but no spark.
Any help would be greatly appreciated.



 
Hohnsz71 
Platinum Supporting Member
Posts: 154
Hohnsz71
Loc: Dayton Texas
Reg: 02-23-15
01-03-18 06:49 PM - Post#2719918    
    In response to 89K5Shane

did you put di-electric grease on the bottom of the Ignition Controle Modual before putting it back on the distributor? if not it will over heat and cook.

2012 silverado, bone stock.
1997 Suburban k2500, under construction.


 
bowtie44s 
Valued Contributor
Posts: 4031
bowtie44s
Age: 35
Loc: wv
Reg: 08-29-12
01-03-18 07:13 PM - Post#2719922    
    In response to Hohnsz71

  • Hohnsz71 Said:
did you put di-electric grease on the bottom of the Ignition Controle Modual before putting it back on the distributor? if not it will over heat and cook.



Heat sink compound. Not dielectric grease.

Jeff

'88 Chevy K3500, aluminum head roller cam 511in³ stroker 10.5:1 compression, 96 NV 4500, 94-98 grille, 305/70-16 (33x12) BF Goodrich KM2s, 91 cluster swap


 
89K5Shane 
Poster
Posts: 33

Reg: 01-03-18
01-03-18 07:28 PM - Post#2719925    
    In response to bowtie44s

I used the compound that came with the mod the first time then got a tube heat sink paste from a computer store and used it on the rest. I used the store brand mod and coil the first time and delco for the others thinking they were better quality. I put a meter on the Dist base and I don't have any voltage leaking to it either. I have spent hours pouring over other forums and can't find an answer...



 
Hohnsz71 
Platinum Supporting Member
Posts: 154
Hohnsz71
Loc: Dayton Texas
Reg: 02-23-15
01-03-18 08:28 PM - Post#2719933    
    In response to bowtie44s

thank you for teaching me instaed of calling me stupid.

2012 silverado, bone stock.
1997 Suburban k2500, under construction.


 
CowboyTrukr 
"7th Year" Silver Supporting Member
Posts: 4014
CowboyTrukr
Loc: Salt Lake City
Reg: 06-20-09
01-03-18 11:26 PM - Post#2719941    
    In response to Hohnsz71

We’re all learners here. 😎

Greg

'95 K1500 Z71 EC Short Step 5.7L+0.040/NV3500
'00 Explorer XLT 4.0 V6 Auto
'94 K2500 5.7 NV4500 ECLB - SOLD
‘87 GMC S15 SCLB 4.3 Auto - SOLD

"The only thing necessary for evil to triumph is for good men to do nothing" Sir Edmund Burke


 
Hohnsz71 
Platinum Supporting Member
Posts: 154
Hohnsz71
Loc: Dayton Texas
Reg: 02-23-15
01-04-18 07:58 AM - Post#2719959    
    In response to 89K5Shane

what about the pins inside of the plug on the ICM or on the coil? maybe they wore out.

2012 silverado, bone stock.
1997 Suburban k2500, under construction.


 
89K5Shane 
Poster
Posts: 33

Reg: 01-03-18
01-04-18 10:35 AM - Post#2719978    
    In response to Hohnsz71

I have cleaned them and they seem to fit tightly.



 
Hohnsz71 
Platinum Supporting Member
Posts: 154
Hohnsz71
Loc: Dayton Texas
Reg: 02-23-15
01-04-18 11:12 AM - Post#2719986    
    In response to 89K5Shane

What about the electronic spark control modual? does yours have that?

2012 silverado, bone stock.
1997 Suburban k2500, under construction.


 
89K5Shane 
Poster
Posts: 33

Reg: 01-03-18
01-04-18 11:56 AM - Post#2719990    
    In response to Hohnsz71

It does and I am trying to find how to test it. I thought it controlled timing and just read that a complete failure will result in a no spark. Any idea how to test it?



 
Chevytech 
Subject Matter Expert - Senior Member
Posts: 3783
Chevytech
Loc: Twin Cities, Minnesota, U...
Reg: 04-25-04
01-04-18 12:16 PM - Post#2719992    
    In response to 89K5Shane

The ESC module uses the knock sensor signal to send a command to the ECM which sends a signal distributor module to control the spark timing. I don't think any failure of the ESC module can make the system have no spark.

It could be poor connections on the wiring that plugs onto the distributor module like Hohnsz71 said. This is getting to be a more common failure as these trucks age.

For those of you that are wondering why you are not getting replies to your thread:

Did you give the model, year, engine, fuel system type, and transmission information?

If your vehicle has been altered from stock, let us know about that too.


 
89K5Shane 
Poster
Posts: 33

Reg: 01-03-18
01-04-18 12:29 PM - Post#2719994    
    In response to Chevytech

Thanks. I am pretty confident that the two wire harness that goes to the coil doesn't have any opens, I took it off and really put it through some pulling and bending with an ohm meter on it and saw no fluctuations. What should I be seeing on the 4 wire connector that plugs into the icm? I am getting 12v to the icm on the pink wire but do not get a signal back on the white while cranking. I just swapped out both the pickup coil and icm and have the same thing. I tested for ground on the icm lugs and it looks solid.



 
Chevytech 
Subject Matter Expert - Senior Member
Posts: 3783
Chevytech
Loc: Twin Cities, Minnesota, U...
Reg: 04-25-04
01-04-18 01:00 PM - Post#2719998    
    In response to 89K5Shane

The four wire connector that plugs onto the distributor module is needed to alter spark timing and is needed by the ECM to trigger the injectors. This system is not dependent on the ECM to produce spark, but the injectors will not trigger if the ECM does not get a distributor reference pulse through the four wire connector.

By saying you are not getting a signal on the white wire you mean that the white wire that goes to the coil does not make a test light blink or have a square wave on it when cranking then the module is not triggering. This would indicate a problem right in the distributor.

These distributors can also have problems because of loss of magnetism needed for the pickup coil to work. If the magnetic material on the shaft in the reluctor wheel area is cracked into pieces replace the shaft or the whole distributor.

Look at this while you are in the distributor:
On these distributors the housing/upper bushing area can get so worn out that the shaft will move sideways so far that the points on the pickup coil pole piece get hit by the reluctor points on the shaft. When this happens the ECM receives compromised signal for RPM and timing issues.



For those of you that are wondering why you are not getting replies to your thread:

Did you give the model, year, engine, fuel system type, and transmission information?

If your vehicle has been altered from stock, let us know about that too.


 
89K5Shane 
Poster
Posts: 33

Reg: 01-03-18
01-04-18 01:43 PM - Post#2720001    
    In response to Chevytech

Thank you for bearing with me on this. I can't find this info after hours online and other forums keep telling me to replace the pickup and icm.
So the ecm only controls the injector pulse and not spark? The reason I asked is that when swapping the icm last time I had fuel pulse but no spark or signal back to the coil. I get a/c voltage coming from the pickup coil when cranking. The shaft and magnets look good and I don't have any play in it and don't see any unusual wear. From what I am getting from this is that the no spark situation is somewhere at the dist since I am getting voltage to the icm and voltage from the pickup. The icm only needs the voltage from the pink wire and a/c from the pickup to fire? It doesn't get a signal from the ecm to fire both fuel and spark?
I feel like I am getting close but am at a loss at this point.



 
89K5Shane 
Poster
Posts: 33

Reg: 01-03-18
01-04-18 02:43 PM - Post#2720009    
    In response to 89K5Shane

Ok tried something new. I don't know the correct terminology but I checked the magnets in the end of the distributor shaft and they are magnetized but if I align them with the points on the base it doesn't magnetize them. Does the sensor in the icm get a signal from that when the magnet passes over it?



 
Chevytech 
Subject Matter Expert - Senior Member
Posts: 3783
Chevytech
Loc: Twin Cities, Minnesota, U...
Reg: 04-25-04
01-04-18 05:25 PM - Post#2720025    
    In response to 89K5Shane

The magnetic field induces voltage in the pickup coil - this is the ac voltage seen when testing the pickup coil while cranking the engine. When the reluctor points line up the change in magnetism, which changes the induced voltage, triggers the module to produce spark.


  • 89K5Shane Said:
So the ecm only controls the injector pulse and not spark? The reason I asked is that when swapping the icm last time I had fuel pulse but no spark or signal back to the coil.

The ECM controls the injector pulse and sends a signal to the distributor module to alter timing, but does not control whether there is spark or not.

When there are injector pulses, but no spark, you know the pickup coil is working in the distributor or because the ECM is getting a distributor reference pulse to trigger the injectors.

If the white wire from the distributor to the coil is not making connection the vehicle can have injectors pulsing with no spark.

For those of you that are wondering why you are not getting replies to your thread:

Did you give the model, year, engine, fuel system type, and transmission information?

If your vehicle has been altered from stock, let us know about that too.


Edited by Chevytech on 01-04-18 05:29 PM. Reason for edit: Clear up wording

 
89K5Shane 
Poster
Posts: 33

Reg: 01-03-18
01-05-18 11:05 AM - Post#2720110    
    In response to Chevytech

Thanks. I will go through the wiring today.



 
89K5Shane 
Poster
Posts: 33

Reg: 01-03-18
01-05-18 01:28 PM - Post#2720128    
    In response to Chevytech

I disconnected the pickup coil again and cranked it now I'm not getting A/c from it. Is that whole star supposed to be magnetized? I am getting what feels like a reverse magnet on the buffers in between the points of the star? I hang a piece of metal by it and the points pull it in and the buffers push it away if that makes sense.



 
Chevytech 
Subject Matter Expert - Senior Member
Posts: 3783
Chevytech
Loc: Twin Cities, Minnesota, U...
Reg: 04-25-04
01-05-18 06:40 PM - Post#2720157    
    In response to 89K5Shane

  • 89K5Shane Said:
I disconnected the pickup coil again and cranked it now I'm not getting A/c from it. Is that whole star supposed to be magnetized? I am getting what feels like a reverse magnet on the buffers in between the points of the star? I hang a piece of metal by it and the points pull it in and the buffers push it away if that makes sense.


Yes, the star piece (reluctor) that is below the rotor should be magnetized. I touch a small end wrench to them to feel the magnetism. When the distributor is out you should be able to feel the magnetic pull as the points pass each other up as you turn the shaft by hand.

These trucks have trouble with the magnetism getting to weak, so the distributor shaft must be replaced. If the shaft needs to be replaced make sure the upper bushing area is not worn so the shaft wiggles sideways.

For those of you that are wondering why you are not getting replies to your thread:

Did you give the model, year, engine, fuel system type, and transmission information?

If your vehicle has been altered from stock, let us know about that too.


 
CowboyTrukr 
"7th Year" Silver Supporting Member
Posts: 4014
CowboyTrukr
Loc: Salt Lake City
Reg: 06-20-09
01-05-18 07:50 PM - Post#2720163    
    In response to Chevytech

Sometimes the reluctor will crack leaving you with an inconsistent magnectic field.

Greg

'95 K1500 Z71 EC Short Step 5.7L+0.040/NV3500
'00 Explorer XLT 4.0 V6 Auto
'94 K2500 5.7 NV4500 ECLB - SOLD
‘87 GMC S15 SCLB 4.3 Auto - SOLD

"The only thing necessary for evil to triumph is for good men to do nothing" Sir Edmund Burke


 
89K5Shane 
Poster
Posts: 33

Reg: 01-03-18
01-17-18 03:07 PM - Post#2721302    
    In response to Chevytech

I had to work on another project and am just now getting back to this. I removed the dist again and when I turn it by hand I get the a/c coming from the pick up coil but when I put it back in the truck and crank it over I get nothing coming out of it. I picked up a new dist and put it in and nothing, no fuel no spark. I test the leads from the pickup and no a/c. If I pull it out and spin it by hand I get a/c. I set it up at TDC for #1 and and turn the engine over by hand and the rotor turns and lines right back up with #1 when I go back to TDC. Any idea why the pickup quits working when it is installed in the truck?



 
Chevytech 
Subject Matter Expert - Senior Member
Posts: 3783
Chevytech
Loc: Twin Cities, Minnesota, U...
Reg: 04-25-04
01-17-18 03:56 PM - Post#2721314    
    In response to 89K5Shane

Is the battery voltage getting so low that when the engine is cranking there is not enough voltage left for the ignition?

Check the battery voltage while cranking.

For those of you that are wondering why you are not getting replies to your thread:

Did you give the model, year, engine, fuel system type, and transmission information?

If your vehicle has been altered from stock, let us know about that too.


 
89K5Shane 
Poster
Posts: 33

Reg: 01-03-18
01-17-18 04:16 PM - Post#2721316    
    In response to Chevytech

Thanks that was one of the first thing I checked. It has a new battery and only 1v dropped while cranking. I turned the new dist by hand and get my a/c when testing across the two wires coming from the pickup but when I put it in the truck and crank it there is nothing. I replaced the dist with a new one thinking the magnets had lost strength in the old one but I get the same thing...



 
Chevytech 
Subject Matter Expert - Senior Member
Posts: 3783
Chevytech
Loc: Twin Cities, Minnesota, U...
Reg: 04-25-04
01-17-18 06:08 PM - Post#2721326    
    In response to 89K5Shane

Because the problems is being so hard to find do not exclude anything previously tested.

If it has a good AC signal turning by hand when removed then it should have a AC wave when installed if the voltage is sufficient.

If you are testing while cranking and don't have the pickup coil unplugged you should try that.
I would test the battery voltage while cranking again too.

Do you still have no spark AND no injector pulse?

You could try the test in the thread in this link to see if you can get spark.
https://www.chevytalk.org/fusionbb/showtopic.php?ti...


Here is another test from my notes that I have not done in decades.

This is a test that will trigger the module using a 1.5 volt battery.

Connect a spark tester to the output terminal of the ignition coil with the tester ground connected to a good ground.

Unplug the four wire connector from the outside of the distributor

Unplug the two wire connector for the pickup coil inside the distributor

Connect a digital volt meter to the Tach terminal by the coil.

Use a jumper to connect the positive end of a 1.5 volt battery to the “P” terminal of the module for the pickup coil and momentarily touch the negative end of the 1.5 volt battery to ground while the key is on and while watching the voltage on the meter connected to the tach lead. The voltage should drop for a moment when the test is done if the module is firing the coil. Keep clear of the spark tester during the test.

Do this test as fast as you can. Just have the 1.5 volt battery connected for a split second.


For those of you that are wondering why you are not getting replies to your thread:

Did you give the model, year, engine, fuel system type, and transmission information?

If your vehicle has been altered from stock, let us know about that too.


 
89K5Shane 
Poster
Posts: 33

Reg: 01-03-18
01-18-18 11:53 AM - Post#2721387    
    In response to Chevytech

I tested it and got a drop and if I bump a ground on the signal wire I get a spark from the coil. While I was in there I just tested the dist body for ground and there isn't any. I am assuming the dist body would be grounded through the shaft and I know the older distributors had a ground wire. Shouldn't I see a solid ground on the body of the dist?



 
89K5Shane 
Poster
Posts: 33

Reg: 01-03-18
01-18-18 12:10 PM - Post#2721389    
    In response to Chevytech

It is still no fuel and no spark even with the dist grounded.



 
Chevytech 
Subject Matter Expert - Senior Member
Posts: 3783
Chevytech
Loc: Twin Cities, Minnesota, U...
Reg: 04-25-04
01-18-18 12:26 PM - Post#2721394    
    In response to 89K5Shane

The base of the distributor should be grounded through its contact with the engine and the contact through the distributor hold down.

Are you sure the distributor is turning when you crank the engine?

For those of you that are wondering why you are not getting replies to your thread:

Did you give the model, year, engine, fuel system type, and transmission information?

If your vehicle has been altered from stock, let us know about that too.


 
89K5Shane 
Poster
Posts: 33

Reg: 01-03-18
01-18-18 12:29 PM - Post#2721395    
    In response to Chevytech

It is turning and lines back up with #1 when I hand turn the crank to TDC for #1.



 
CowboyTrukr 
"7th Year" Silver Supporting Member
Posts: 4014
CowboyTrukr
Loc: Salt Lake City
Reg: 06-20-09
01-18-18 12:38 PM - Post#2721398    
    In response to 89K5Shane

The electronics in the distributor do not rely on any grounding to the distributor body.

I would not presume to take overboard a thread that Chevytech is helping you with. One thing to check: what condition are the grounds at the thermostat housing? Those are the computer grounds.

Greg

'95 K1500 Z71 EC Short Step 5.7L+0.040/NV3500
'00 Explorer XLT 4.0 V6 Auto
'94 K2500 5.7 NV4500 ECLB - SOLD
‘87 GMC S15 SCLB 4.3 Auto - SOLD

"The only thing necessary for evil to triumph is for good men to do nothing" Sir Edmund Burke


 
89K5Shane 
Poster
Posts: 33

Reg: 01-03-18
01-18-18 12:42 PM - Post#2721399    
    In response to CowboyTrukr

Thanks I will check it right now. The only thing I can come up with is the pickup coil is producing a charge out of the truck when I hand crank it and nothing when its in the vehicle cranking. I have a brand new dist and all the components in there now and its doing the same thing as the old one.



 
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