Blazer no start after heater core

Hey guys i have a 94 Blazer s-10 4.3Lt and i replaced my heatercore and now it will not start just keep cranking like its getting no fuel, i searched for this topic i think it was cover a long time ago but i did'nt find it. Any help would be appeciated, and if you guys need more information please tell me

Have a close look and see if you got everything plugged back up or knocked some wires off or unplugged them.
If all ok check for spark to 2 or more spark plugs.
Can you hear fuel pump run?

Have a close look and see if you got everything plugged back up or knocked some wires off or unplugged them.
If all ok check for spark to 2 or more spark plugs.
Can you hear fuel pump run?

Hey yesterday i checked spark on all 6 cylinders, and all were getting spark, also i tested fuel pressure at the scharer valve, got 60 when priming to start, and 10 PSI when cranking. So then i checked the fuel filter, replaced it with a new one and still not turning over, got the same results. Any ideas, were going to rip apart the dash again to make sure everything is connected. Do you think the fuel pump might have went?

if it was running before you changed heater core there must be something unplugged?? if you think it's pump have someone turn key on while you listen inside gas neck..but 60lbs should be good to go...

Hey yesterday i checked spark on all 6 cylinders, and all were getting spark, also i tested fuel pressure at the scharer valve, got 60 when priming to start, and 10 PSI when cranking. So then i checked the fuel filter, replaced it with a new one and still not turning over, got the same results. Any ideas, were going to rip apart the dash again to make sure everything is connected. Do you think the fuel pump might have went?

The 10 lbs on cranking is not good.
You need the full pressure of 64-65 lbs on a cold start cranking for injectors to squirt and start engine.
Jumper the fuel pump with a 12 volt fused jumper on the fuel pump prime test connector or the fuel pump gray wire fuel pump feed.
And see if the pressure will hold 63-64 lbs and engine will start up and run.
Is the security light coming on and going off key on?
MT

Will the fuel pump run on the 30 second key on prime up?

The 10 lbs on cranking is not good.
You need the full pressure of 64-65 lbs on a cold start cranking for injectors to squirt and start engine.
Jumper the fuel pump with a 12 volt fused jumper on the fuel pump prime test connector or the fuel pump gray wire fuel pump feed.
And see if the pressure will hold 63-64 lbs and engine will start up and run.
Is the security light coming on and going off key on?
MT

Will the fuel pump run on the 30 second key on prime up?

To the two other post the fuel pump is powering up at the intial key insertion and priming even after trying to start for a few seconds it comes back on when you stop cranking. Today we changed the fuel filter and now we are getting a 60-70 PSI at cranking now. If you stop cranking it drops down to about 10-20 PSI after a few seconds. Start to crank and goes back up to 60-70 PSI. Today we verifed all the fueses were good and retested all ignition wires and coil wire. My brother said he thinks there was something behind the instument cluster unhook like wire wise. But the fuel pump seems to be working fine and were getting spark. Going to check into the wire behind the dash tommorrow only thing i can think of is the computer, i do know know where it is located.

PS. MT we have no secuirty light its a 94?

...If you stop cranking it drops down to about 10-20 PSI after a few seconds. Start to crank and goes back up to 60-70 PSI.


There's your problem. When you stop cranking, the pump will run for approximately 2 to 3 seconds. After the fuel pump shuts off, fuel pressure must remain above 55psi for several minutes. There's a leak either in the fuel regulator or the lines, both are under the upper intake manifold.

To the two other post the fuel pump is powering up at the intial key insertion and priming even after trying to start for a few seconds it comes back on when you stop cranking. Today we changed the fuel filter and now we are getting a 60-70 PSI at cranking now. If you stop cranking it drops down to about 10-20 PSI after a few seconds. Start to crank and goes back up to 60-70 PSI. Today we verifed all the fueses were good and retested all ignition wires and coil wire. My brother said he thinks there was something behind the instument cluster unhook like wire wise. But the fuel pump seems to be working fine and were getting spark. Going to check into the wire behind the dash tommorrow only thing i can think of is the computer, i do know know where it is located.

PS. MT we have no secuirty light its a 94?


I missed on the fuel pressure specs and security light.
The specs should be 55/61 lbs of pressure on a 94
If the fuel pressure is going over spec or droppng down real fast after fuel pump shuts off.
You have a problem inside the spider injector.
60-70 at cranking is to high and a fast leak down indicates a leak in there.
Which could cause flooding.
Pull the sparks plugs and see if they are flooded or real wet on the ends.

I missed on the fuel pressure specs and security light.
The specs should be 55/61 lbs of pressure on a 94
If the fuel pressure is going over spec or droppng down real fast after fuel pump shuts off.
You have a problem inside the spider injector.
60-70 at cranking is to high and a fast leak down indicates a leak in there.
Which could cause flooding.
Pull the sparks plugs and see if they are flooded or real wet on the ends.
Turns out your right spider fuel injector took a crap. Ordered a kit online to do the job with all ac-delco parts. This should be fun!

Thanks for posting back what you found.
Glad you found the problem and let us know how it goes.
Run a search on here.
There should be some how to or other post with the replace procedure.
If not post back if you need help on it.
And good deal on the AC-Delco parts.
MT