[Hozay]

UPDATE** It’s not getting fuel *
SES still doesn’t come on with key on. I’m assuming the bulb burnt out so I move onto crank no start. I have spark so I poured a little fuel in the throttle body and it fired right up then died. So I’m onto no fuel.

I have a 1990 S10 Blazer 4.3 4x4 with some issues. It has always run ok then BOOM turns off while at a stop sign. I cranked it over it started but it was coughing and engine was shaking pretty bad. Next day no issues at all and I drove it around quite a bit. Since it was ok I needed to replace the heater core and I started on that. Heater core is done so I decide to do the cap, rotor, wires, plugs, why not? I did the cap, rotor and wires turn it over and it will not start. It cranks great and that’s when I noticed the check engine light was not coming on at all. There were no codes stored before I did the heater core. I want to fix the check engine light before I look into the crank no start. Was it my luck the bulb burned out or did I cause a problem when I changed parts?? Any help would be appreciated.

 

[oldeerslayer]

When you first turn the key to ON the SES light should come on for a few seconds as a bulb test.
Sounds like you might not have something plugged in at the distributor or the cap or rotor is not on correctly for the no start issue.

 

[LittlewhiteS10BLAZER]

I have a 1990 S10 Blazer 4.3 4x4 with some issues. It has always run ok then BOOM turns off while at a stop sign. I cranked it over it started but it was coughing and engine was shaking pretty bad. Next day no issues at all and I drove it around quite a bit. Since it was ok I needed to replace the heater core and I started on that. Heater core is done so I decide to do the cap, rotor, wires, plugs, why not? I did the cap, rotor and wires turn it over and it will not start. It cranks great and that’s when I noticed the check engine light was not coming on at all. There were no codes stored before I did the heater core. I want to fix the check engine light before I look into the crank no start. Was it my luck the bulb burned out or did I cause a problem when I changed parts?? Any help would be appreciated.

I had an issue like that that constantly got worse about a year ago. Turns out my Ignition Control Module (ICM) went out. It would work sometimes, but then the engine would die.

It is that black module on the distributor housing right underneath the cap.

 

[Hozay]

When you first turn the key to ON the SES light should come on for a few seconds as a bulb test.
Sounds like you might not have something plugged in at the distributor or the cap or rotor is not on correctly for the no start issue.

I get some lights to come on but not the SES. I was thinking I did something wrong with the wires but I’ve checked the cap, rotor, and wires they all seem correct.

 

[Hozay]

I had an issue like that that constantly got worse about a year ago. Turns out my Ignition Control Module (ICM) went out. It would work sometimes, but then the engine would die.

It is that black module on the distributor housing right underneath the cap.

Gotcha, I’ll check it out.
Thanks

 

[Rhotpursuit]

Have you tried the paperclip trick to check for codes? @oldeerslayer can help with that. As for the light..maybe it's just b urned out.

 

[Hozay]

Have you tried the paperclip trick to check for codes? @oldeerslayer can help with that. As for the light..maybe it's just b urned out.

I have and there were zero codes. Then I replaced parts and now I the SES doesn’t come on at all so I cannot use the paper clip trick.

 

[LittlewhiteS10BLAZER]

I have and there were zero codes. Then I replaced parts and now I the SES doesn’t come on at all so I cannot use the paper clip trick.

What all parts did you replace?

Also, here is the test procedure with pictures from the Haynes Repair Manual for the ICM, if you think it may be the problem.

 

[bnokle]

I had a new 93 and the cap and rotor would fail every 40000 kms or whatever that is in miles and run great and then it would just die. Or not restart. And like clockwork it would go so much so I carried an old cap and rotor, along with a screw driver and a strip of emery cloth. I don't get stuck anywhere. Usually I have a 90 that eats distributors but has a dui coil and module in it and that seems to help with the cap corrosion for some reason and its never left me stranded anywhere. Just the buzzing of the rotor eating the cap which would go away after it warmed up

 

[LittlewhiteS10BLAZER]

ICM Pinout

 

[Hozay]

What all parts did you replace?

Also, here is the test procedure with pictures from the Haynes Repair Manual for the ICM, if you think it may be the problem.

Awesome, thanks
I changed the heater core, cap, rotor, and wires

 

[DaveP]

If the SES does not come on and stay on with the key in run, the ECM is not powered-up, and the engine will not start.

Check fuses ECM A, ECM B, GAUGES. (Could also be labeled ECM 1, ECM 2)

If you worked under the dash for the heater core, re-check the connectors into the ECM and the white 10-cavity connector about 6" from the ECM for being tight and secure.

 

[Hozay]

Thanks Dave, I updated my earlier post. I did check the fuses and connections, I'm not getting fuel. I assumed the bulb was burnt out for SES light and tried to figure out the no start. It has spark so I poured a little fuel in the throttle body and it fired right up then died. The SES still doesn't come on with the key in run.

 

[oldeerslayer]

Check to see that you are getting power to the pump. And it's the ground wire is ok. There is a fuel pump test port on the firewall. It look like a single wire connector that isn't connected to anything. If you apply 12V to it the pump will get those 12V and should run if the pump has ground and is OK. Since you changed the heater core did you move or bump any of the relays on the fire wall. Not sure on a 95 but most 1st gen fuel pump relays are right above where you were working.

 

[Hozay]

Check to see that you are getting power to the pump. And it's the ground wire is ok. There is a fuel pump test port on the firewall. It look like a single wire connector that isn't connected to anything. If you apply 12V to it the pump will get those 12V and should run if the pump has ground and is OK. Since you changed the heater core did you move or bump any of the relays on the fire wall. Not sure on a 95 but most 1st gen fuel pump relays are right above where you were working.

I got 12V to test connector and I can hear the pump run in the tank but it will not start. I cannot hear the pump running if I put the key in the on position. I put a 9V battery to each injector and both click fine. The throttle body is definitely dry.

 

[oldeerslayer]

Pump only runs a few seconds when the key is on. To prime the engine. Then it waits for the ECM to trigger the relay. Which happens as soon as the ECM gets a pulse from the distributor pickup. If you crank long enough to build oil pressure that will also turn on the pump. Last couple years GM deleted that redundancy.
It's done that way as a safety feature. If the engine isn't running and the key is on, like in a roll over, you don't need the pump pressurizing the fuel system. Or if you simply have a faulty injector that leaks you don't want fuel filling the engine because the key is on.

 

[Hozay]

Pump only runs a few seconds when the key is on. To prime the engine. Then it waits for the ECM to trigger the relay. Which happens as soon as the ECM gets a pulse from the distributor pickup. If you crank long enough to build oil pressure that will also turn on the pump. Last couple years GM deleted that redundancy.
It's done that way as a safety feature. If the engine isn't running and the key is on, like in a roll over, you don't need the pump pressurizing the fuel system. Or if you simply have a faulty injector that leaks you don't want fuel filling the engine because the key is on.
[/QUOT

Pump only runs a few seconds when the key is on. To prime the engine. Then it waits for the ECM to trigger the relay. Which happens as soon as the ECM gets a pulse from the distributor pickup. If you crank long enough to build oil pressure that will also turn on the pump. Last couple years GM deleted that redundancy.
It's done that way as a safety feature. If the engine isn't running and the key is on, like in a roll over, you don't need the pump pressurizing the fuel system. Or if you simply have a faulty injector that leaks you don't want fuel filling the engine because the key is on.

Makes sense, I guess I need to check the pickup pulse to ECM now. How would I do that?

 

[Hozay]

Check to see that you are getting power to the pump. And it's the ground wire is ok. There is a fuel pump test port on the firewall. It look like a single wire connector that isn't connected to anything. If you apply 12V to it the pump will get those 12V and should run if the pump has ground and is OK. Since you changed the heater core did you move or bump any of the relays on the fire wall. Not sure on a 95 but most 1st gen fuel pump relays are right above where you were working.

You were right I loosened one of the connectors at the computer. I secured it and she fired right up. SES comes on and turns off at start up, thanks for the help.

 

[WadeSchweitzer]

"I needed to replace the heater core and I started on that. Heater core is done so I decide to do the cap, rotor, wires, plugs, why not? I did the cap, rotor and wires turn it over and it will not start." - Hozay

Sounds like a "Blunders" article, in the RockAuto newsletter. "It usta' work - I did this - now, it don't work!" Go back to the last thing you did. Don't fret too much though. Same thing happens in shops - professionally. Lessons learned.

 

[PeteD]

You were right I loosened one of the connectors at the computer. I secured it and she fired right up. SES comes on and turns off at start up, thanks for the help.

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