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Discussion Starter #1
I have a 91 S10 2.8L regular cab truck. I was changing the distributor and while I was tightening down the distributor bolt my wrench touched the junction box on the firewall that has power from the battery. It of course sparked and now I'm not sure what I broke to make my truck not start.
First thing I noticed was no fuel from the injectors and my head lights don't work. Here is what I've checked so far:
1. Battery is still good.
2. Power still at the junction box.
3. Power at the back of the alternator (fusible link).
4. ECMB fuse in the fuse box in the driver floorboard is good.
5. Switched fuel pump relay with the A/C relay and bought a new relay.
6. Orange wire at fuel pump relay has power.

I can't find the test point for the fuel pump to bypass the system to test it.
I did find a wire with a cap over it on top of the brake booster. Any idea what that is? I didn't want to apply power to it until I know what it is.
Any ideas on what I should test next or an idea of what the problem might be or suggestions?

Thanks
91 S10 2.8L regular cab manual
Joe
 

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overthinker extraordinar
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649 Posts
I have a 91 S10 2.8L regular cab truck. I was changing the distributor and while I was tightening down the distributor bolt my wrench touched the junction box on the firewall that has power from the battery. It of course sparked and now I'm not sure what I broke to make my truck not start.
First thing I noticed was no fuel from the injectors and my head lights don't work. Here is what I've checked so far:
1. Battery is still good.
2. Power still at the junction box.
3. Power at the back of the alternator (fusible link).
4. ECMB fuse in the fuse box in the driver floorboard is good.
5. Switched fuel pump relay with the A/C relay and bought a new relay.
6. Orange wire at fuel pump relay has power.

I can't find the test point for the fuel pump to bypass the system to test it.
I did find a wire with a cap over it on top of the brake booster. Any idea what that is? I didn't want to apply power to it until I know what it is.
Any ideas on what I should test next or an idea of what the problem might be or suggestions?

Thanks
91 S10 2.8L regular cab manual
Joe
I'll double check my schematics and see if I can identify a possible issue. My gut says this is a coincidence, your truck not starting and the spark. I think that junction on the firewall is for accessories, and independent of the rest of the truck. I am not certain, so hang on until I get a chance to double check.

Bummer for sure.
 

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overthinker extraordinar
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649 Posts
What does the truck do, or not do when you try to start it?

Does the junction box have the following four wires:
red, red/black, pink, pink/black?

The schematic I have does not clearly identify the j-box. However, if this is it, there is a fuse that is on the red wire that connects to the ignition switch.
mark
 

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Boozebag
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9,265 Posts
There is a wire by the distributor closer to the firewall that is blueish gray (test point) that fires the fuel pump. It is not connected to anything.
Same color wire to the fuel pump relay. If you run + power to this, the fuel pump lights off.

If you don't have power to the headlights, I bet you popped a fusible link.
There are 2 at the back of the alternator. If you have power there, the link is good from the battery.
The other link goes to the inside of the truck. Check that. If you pull it from both sides, and it is bad, the cover will stretch apart. You can also stick it with a test light on the side away from the alternator to see if there is power.
The hot wire on the firewall is the positive 'buss' that is for accessories like the engine compartment light. It has power all of the time. Try checking for power with a test light. IIRC, it also has a fusible link. If no power, follow the red wire to the battery and see if there is a break there.
You can also run a jumper wire to it - if it's dead - to see if the truck runs again.

AND... I know it's too late, but next time disconnect the battery... :p
 

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Awww..you ain't got shit!
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Spray some ether or pour a little fuel in the TBI. See if it lights up. If so you got spark! Do you hear the pump coming on when you first turn the key on?

Oh...this may sound impossible. But you said you changed your distributor? Make sure that 4 wire plug is plugged the correct direction. It should not fit but one way, but if the harness plug is worn, it may connect backwards and you will get a no start situation. Ask me how I know this...I managed it myself. Turned it around...guess what? It ran. Pretty amazing shit there.
 

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Discussion Starter #6
The starter works and the truck turns over, but the fuel injectors never spray fuel. I believe it tried to start last time I sprayed starting fluid in the throttle body, but I will check that again to be sure.

The junction box looks like it has 3 red wires not counting the under the hood light. I included a picture. One is coming from the battery, One is going to the back of the alternator and the other seems to run into the main harness. I'm guessing the one that runs into the harness also has a fusible link on it?

The fusible link on the back of the alternator seems fine. I will have to try and find the other one. Any idea where it is roughly?

I'll double check the plug on the distributor to make sure I didn't flip that.

My replies might be a little spaced out because the truck isn't at my house, but my brothers. Thank you for the suggestions, I really appreciate it and I feel really dumb for not disconnecting the battery as I normally do.

Thank You
 

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Boozebag
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9,265 Posts
It's funny... they apparently put the fusibles in different places when the variuos engines are installed. Like the 2.8, 2.5 and 4.3...
One of my 2.5 trucks has 2 fusible links on the wires coming from the alternator. My V8 truck has them by the starter...
Haunted...
If you have power to the firewall link, then you may have to check the back of the fuse panel. I remember someone on the forum had a similar problem and it turned out the fuse panel had bombed...
Don't ask me how that would relate to your situation... :dunno:
 
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