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01-17-2010, 02:07 AM #1
1990 Silverado v8 starting issues
Please ask as many questions as you like. I really need some help with this. :(
Guys, I need some serious help with this one. I feel as though I have troubleshot EVERY possible item on the truck and it just won't start. Let me give a brief history of what I'm dealing with.
This is a 1990 gas-powered v8 Silverado chassis with the standard setup. It has a carb-injection setup with 2 injectors, nothing fancy. This guy brought the car over to my house so I could do some work on it and kind of clean it up. The top shell of the truck is a 57 Chevy, but all the internals are from the Silverado. The truck looks great on the outside, but the wiring and overall "cleanliness" of the engine bay lacks order. So I thought I would do him a favor and organize things for him. Well this has turned out to be a HUGE drawn out deal and now that I am about to get the car back together, it won't start.
I have all of the connectors that are for the motor connected. I am getting voltage (12.x volts) to the coil pack and fuel to the injectors, but there doesn't seem to be any spark when it tries to turn over. I can read 12 volts at the pigtail where it goes to the coil, but from there I can't get spark at the plug. Although I am getting fuel and the pump is priming, there doesn't seem to be any spray when you try and start it. Not sure if it's waiting on the coil to spark or what, but there is fuel in the line coming to the injectors. I have checked all grounds, all power wires, computer connectors, etc. and everything is in place. My plan was to kind of organize and clean up the harness, but I never did get around to doing any of that. And what I'm saying is, nothing has changed since I pulled the harness out to work on it, which is why I am stumped. Obviously SOMETHING changed, but I'm just saying I didn't remove or cut any wires. I DID re-terminate wires for the starter and the solenoid, but obviously those wires are fine because I can engage the starter. I even pulled the fuel tank to confirm the hose going from the pump to the supply line didn't come loose.
The car was parked about 10 months ago and hadn't been started since. Are there any things that can go bad on a truck that I should look for? I seriously need this thing out of my driveway and gone so I can focus on other projects of my own. Any advice or suggestions would be appreciated. And he's wants to sell it if anyone wants to come and pick it up.
01-17-2010, 03:40 PM #2
I think I have it narrowed down to the coil. There are 2 wires coming in (pink from the column ignition, white from/to the tach?), there are two wires going out to the distributor and then the coil wire. There is definitely 12v going in, but nothing going out to the distributor when trying to crank it. I tried grounding a plug while someone else started it and nothing and I also tried a test light connected to the coil wire and grounding that and still nothing. Is there anything else that would keep the coil from producing current? I mean, do the two wires going to the distributor produce a signal TO the coil to tell it where the rotor is, is that how that works? The white wire going to the tach is not hooked up to anything because he has custom gauges and no tach. But I don't remember that being hooked up to anything before.
One other thing, is the coil grounded some other way besides being bolted to the engine?
Thanks again for any advice.
01-17-2010, 04:28 PM #3
I tested the coil and everything is measuring 8 ohms of resistance. That doesn't tell me a whole lot, but it tells me that it's getting current from the 4 pins to the coil sending terminal. Which is making me think that the problem is with the pickup unit that sits under the distributor. Any electrical/ignition guys want to throw me a bone please? I'm used to working on Dodge's and just don't where else to troubleshoot from here. My initial though is I have the main problem figured out, fire, but with the headache of problems this truck has potential for, any and all help is going to be VERY much appreciated.
Last edited by minigts; 01-17-2010 at 05:12 PM.
01-18-2010, 11:15 AM #4
- Join Date
- Jan 2010
These are famous for killing the pickup coil and module under the distributor. Look at the pickup and see if the yellow or white wrapping around it is coming apart and leaving little bits inside the distributor. Also, the module is the most likely thing to go when you have no spark.
01-18-2010, 01:23 PM #5
Thanks again Tim!
01-23-2010, 12:04 PM #6
Is there a way to do a test of this piece? I only have an ohm meter and a test light. Is there something I can do, like send 12 volts to one of the pins and test for some output voltage or something? I will more than likely replace it since it seems to be the issue, but it's $40 at the store and I'm not getting paid to fix this thing. LOOONG story, but just wondering if there is something I can do before I buy a new piece.
Also, the round piece under the rotor, is that something I should worry about? It seems rusted to the shaft and I couldn't remove it.
And to answer your question Tim, there were no broken pieces, everything was in tact.
01-24-2010, 03:47 PM #7
Well I tested the module and that was the problem. Thankfully I can now get it to fire, but to get to this piece I took the wires off and now I don't know which post on the cap is #1. :$ Anyone know which is which on the cap? The motor is a 5.7 v8 with the distributor on the rear. There is a divider on the cap, so if anyone knows which is #1 in relation to this, that would be greatly appreciated. This is the cap.
01-25-2010, 04:17 PM #8
- Join Date
- Jan 2010
1-8-4-3-6-5-7-2 is the usual firing order, sometimes printed on the intake manifold. The driver side of the motor from front to back is 1-3-5-7 cylinders, the passenger side from front to back is 2-4-6-8. If you are looking at the distributor from the front it rotates clockwise. Number 1 is usually at the 5 O' Clock position. Of course, you can always rotate the motor until the crankshaft lines up with 0. Then pull the #1 plug and see if the piston is up top. That way you know you're on the intake stroke. Then pull the cap and wherever the rotor is pointing that's #1.
01-25-2010, 07:07 PM #9
Well that is what I needed to know. The diagrams I found put #1 at like 12 o'clock and then I found that there could be more than 3 different firing orders for v8 Chevy's? I just don't get it. I'm a 4 cylinder guy and we just have it easy. :p Thanks again Tim.
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