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TBI problems after changing injectors

No spark, no fuel. However when I took it apart it did dump a bunch of fuel because I didn't do the pull the plug disconnect the fuel pump thing. I didn't try to start it until the next day when it went clunk. I have checked for spark at #1 plug with a tester and on the coil to coil wire.

I fixed some wiring issues tonight and got solid 12 volts to the fuel pump again. I am checking out some wiring under the dash so haven't had a chance to try it again. I think I will pick up new plugs tomorrow, I already have new wires to put on anyway. Other things I have already done is new ignition module, new coil, new ignition switch in the dash, new computer under the dash GM 7747. I swapped the chip and prom if that is what they are called.

I will keep you posted. I tried to throw in the towel but my favorite local shop can't touch it for 3 weeks so guess I will be learning.
 
500$k5 said:
In order. EGR Valve controller
Throttle position sensor (TPS)
Idle air control valve (IAC)
Exhaust Gas Recirculation Valve (EGR)
Electronic Spark Timing Module (EST)
The one above the egr in pic 6 is the Manifold Absolute Pressure Sensor (MAP)
Click to expand...
Awesome info, anyway to test any of those? I will also look in my manuals, appreciate any help too!
 
70jimmy said:
No spark, no fuel. However when I took it apart it did dump a bunch of fuel because I didn't do the pull the plug disconnect the fuel pump thing. I didn't try to start it until the next day when it went clunk. I have checked for spark at #1 plug with a tester and on the coil to coil wire.

I fixed some wiring issues tonight and got solid 12 volts to the fuel pump again. I am checking out some wiring under the dash so haven't had a chance to try it again. I think I will pick up new plugs tomorrow, I already have new wires to put on anyway. Other things I have already done is new ignition module, new coil, new ignition switch in the dash, new computer under the dash GM 7747. I swapped the chip and prom if that is what they are called.

I will keep you posted. I tried to throw in the towel but my favorite local shop can't touch it for 3 weeks so guess I will be learning.
Click to expand...
I assume you’ve checked the ECM connectors at the back of the computer? I had a wire back out on me when I was swapping computers. Might be good to check it along with all the fuses and obvious stuff just to make sure.
 
All the wires on the connectors seem good, but I will check again. Yep gone through all the fuses, in line and otherwise. I may just order a new fuse block and harness since I would feel better if that was replaced sometime. Still have the original fuse block with the round glass fuses, along with some extras that were added. All fuses checked for continuity using the voltmeter.

I have read some stuff about computers needing reflashed? Anyone have input on that, what does it take to do it?
 
If you swapped in the prom chips, it should work, as long as those were not the issue

@ZooMad75 you or @Larry have .02$ on this?
 
Make sure the chip didn’t go in backwards. That wrecks it. Ask me how I know. :doah: But even if you did, it should at least start and run poorly even if the computer was bad.
 
The computer looks for the pulses from the pickup coil in the distributer, to fire the spark, and the injectors. If the pickup coil is bad, you won't get spark, or injectors. Does the fuel pump pump for 2 seconds and turn off, when the ignition is first turned on?
 
I don't believe that the egr, tps, iac, est, or map sensor, will stop you from getting spark and fuel both, unless they have blown a fuse somewhere.
 
bp71k5 said:
Make sure the chip didn’t go in backwards. That wrecks it. Ask me how I know. :doah: But even if you did, it should at least start and run poorly even if the computer was bad.
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TBI ecm's were not programmable at the dealer level. The prom (chip) was the program specific to the vehicle. Engine size, trans, gearing and such. The ECM itself didn't contain any data or calibration for fuel trim/spark timing. That's all in the prom. So as long as the prom is ok from the old ecm it should work in the new ECM.

Outside of getting zapped from static electricity when removing/installing the proms rarely fail. The bigger issue is if a prom does fail I have no way of getting one through GM. Long been discontinued. I'm sure there are guys out there selling them but I haven't done the research to look for any.
 
ZooMad75 said:
TBI ecm's were not programmable at the dealer level. The prom (chip) was the program specific to the vehicle. Engine size, trans, gearing and such. The ECM itself didn't contain any data or calibration for fuel trim/spark timing. That's all in the prom. So as long as the prom is ok from the old ecm it should work in the new ECM.

Outside of getting zapped from static electricity when removing/installing the proms rarely fail. The bigger issue is if a prom does fail I have no way of getting one through GM. Long been discontinued. I'm sure there are guys out there selling them but I haven't done the research to look for any.
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I meant don’t install the PROM backwards in the new ECM. I don’t remember if that’s possible with the stick setup but with the removable aftermarket chip setup it can happen. But even then the motor should at least run, albeit poorly cause it’s in “limp” mode.
 
SUCCESS!!! :bow: Thanks everybody for all the :1zhelp:

Several things were bad, a couple connections at the positive battery cable were poor, a few connections at the fuse box were bad, a blown fuse not related to engine issues, Fixed a couple of other poor wiring connections not related to the engine. Plug wires: 3 had big cracks or breaks in the boots, 2 had bad plug clips, not sure if one was from removing wire but 2 of them the clips stayed with the plugs. Plugs were still good all had an even coat of burn on them. Distributor pick up coil wiring one of the wires fell out of the plug and the other one was loose. Old distributor had no resistance when you spin the drive gear/rotor, new one had more.

Things I replaced: Coil, plug wires, spark plugs, complete distributor including cap, after trying new ignition module. Ignition switch in dash old one had a lot of play in it anyway. New injectors which started the whole mess. I also put heat protector sleeves on the plug wires at the plug, I think the heat from the motor and rams horn manifolds kills the boots, I am interested to see how these perform. Main computer under the dash 7747. Well now I have more spare parts.

Now I need to verify the timing is correct, manual says it should be 6 degrees before top dead center and re mount the computer.

Officially beginning blazer bash prep. :woot:
 
70jimmy said:
SUCCESS!!! :bow: Thanks everybody for all the :1zhelp:

Several things were bad, a couple connections at the positive battery cable were poor, a few connections at the fuse box were bad, a blown fuse not related to engine issues, Fixed a couple of other poor wiring connections not related to the engine. Plug wires: 3 had big cracks or breaks in the boots, 2 had bad plug clips, not sure if one was from removing wire but 2 of them the clips stayed with the plugs. Plugs were still good all had an even coat of burn on them. Distributor pick up coil wiring one of the wires fell out of the plug and the other one was loose. Old distributor had no resistance when you spin the drive gear/rotor, new one had more.

Things I replaced: Coil, plug wires, spark plugs, complete distributor including cap, after trying new ignition module. Ignition switch in dash old one had a lot of play in it anyway. New injectors which started the whole mess. I also put heat protector sleeves on the plug wires at the plug, I think the heat from the motor and rams horn manifolds kills the boots, I am interested to see how these perform. Main computer under the dash 7747. Well now I have more spare parts.

Now I need to verify the timing is correct, manual says it should be 6 degrees before top dead center and re mount the computer.

Officially beginning blazer bash prep. :woot:
Click to expand...
Glad you got it going!
 
70jimmy said:
SUCCESS!!! :bow: Thanks everybody for all the :1zhelp:

Several things were bad, a couple connections at the positive battery cable were poor, a few connections at the fuse box were bad, a blown fuse not related to engine issues, Fixed a couple of other poor wiring connections not related to the engine. Plug wires: 3 had big cracks or breaks in the boots, 2 had bad plug clips, not sure if one was from removing wire but 2 of them the clips stayed with the plugs. Plugs were still good all had an even coat of burn on them. Distributor pick up coil wiring one of the wires fell out of the plug and the other one was loose. Old distributor had no resistance when you spin the drive gear/rotor, new one had more.

Things I replaced: Coil, plug wires, spark plugs, complete distributor including cap, after trying new ignition module. Ignition switch in dash old one had a lot of play in it anyway. New injectors which started the whole mess. I also put heat protector sleeves on the plug wires at the plug, I think the heat from the motor and rams horn manifolds kills the boots, I am interested to see how these perform. Main computer under the dash 7747. Well now I have more spare parts.

Now I need to verify the timing is correct, manual says it should be 6 degrees before top dead center and re mount the computer.

Officially beginning blazer bash prep. :woot:
Click to expand...
Timing should be 0 degrees with the timing connector unplugged.
 
bp71k5 said:
Timing should be 0 degrees with the timing connector unplugged.
Click to expand...
Yep saw that on some you Tube videos, there was an insert with the dizzy that talked about 6 degrees for 88 - 91 firebird, but I did some research before I trusted it.

So can I unplug the small connecter at the dizzy or do I have to be able to just disconnect the one wire in that connector? The brown wire goes directly into a wire loom, I haven't looked yet to see if there is something under the dash with a disconnect for it. It's a Howell harness with the computer. Time to hunt my wiring diagrams.
 
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