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Spark to engine.

Tiny
CHEVYS10BLAZER43L
  • MEMBER
  • 2000 CHEVROLET BLAZER
  • 4.3L
  • 6 CYL
  • 4WD
  • AUTOMATIC
  • 295,000 MILES
I have rebuilt my 4.3l engine I have changed the Ignition coil, distributor, spark plug wires, spark plugs, ignition control module. I am not getting any spark at all. I have to use a jumper wire from the positive battery post to the ECM 1 fuse and the under the hood fuse box to get it to start. It turns over fine. When I use the jumper wire to the ECM 1 fuse it starts up but as soon as it starts it jumps to very high rpm's as if someone is holding the gas pedal to the floor but we are not touching the throttle at all. We have also replaced the idle air control valve and the throttle position sensor. Need major help please.
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Monday, June 6th, 2016 AT 8:17 PM

16 Replies

Tiny
HMAC300
  • MECHANIC
  • 48,601 POSTS
Try resetting the security system and check fuses and relays under-hood. This could be a fuse box problem with the fuse you are talking about, but it may be just security because I am assuming the battery was disconnected. This is on the cusp of where GM changed security so if what I send you does not work try another key.
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Tuesday, June 7th, 2016 AT 5:59 AM
Tiny
CHEVYS10BLAZER43L
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  • 10 POSTS
Okay and if that does not work. What will be the next steps to figuring out the issue?
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Tuesday, June 7th, 2016 AT 8:33 PM
Tiny
CHEVYS10BLAZER43L
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Ok and if that does not work. What will be the next steps to figuring out the issue?
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Tuesday, June 7th, 2016 AT 8:33 PM
Tiny
HMAC300
  • MECHANIC
  • 48,601 POSTS
Check to see if rotor in distributor is turning if not the gear is stripped on bottom and you need another distributor or pull it out and check to see if it is. But a lot easier pulling cap. Then scan for codes you can either rent one at auto parts or buy one the are pretty cheap. Also check under hood fuses and relays.
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Wednesday, June 8th, 2016 AT 6:12 AM
Tiny
CHEVYS10BLAZER43L
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Okay, fuses and relays are good. The rotor and gears are all fine. And there are no codes.
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Wednesday, June 8th, 2016 AT 12:41 PM
Tiny
HMAC300
  • MECHANIC
  • 48,601 POSTS
In my first reply I said the fuse box can be bad so you will have to check that to see if the plug in or connection is bad or corroded. You can try some dielectric compound on the fuse prongs and try somehow to clean the connection. The dielectric can be purchased at auto parts for about $2.00 for a small tube a lot of times it sitting on the front counter.
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Wednesday, June 8th, 2016 AT 12:52 PM
Tiny
CHEVYS10BLAZER43L
  • MEMBER
  • 10 POSTS
What are my chances that the computer system is bad? How can I tell if the computer is not working?
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Wednesday, June 8th, 2016 AT 5:29 PM
Tiny
HMAC300
  • MECHANIC
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If it ran before and now wont I kind of doubt it is the computer. Did you try a security reset like I said in very first reply? Have you scanned for codes? Checked fuel pressure? These have to be done when you get a no start.
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Thursday, June 9th, 2016 AT 5:35 AM
Tiny
CHEVYS10BLAZER43L
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  • 10 POSTS
I have done all that and all fuses are good. Everything is fine. I have replaced every thing to do with spark brand new I have replaced starter a few plugs for wiring harness. I put all new fuses in box. When I tested the fuses some tested good only on a grounded connection and the ones that didn't tested good off positive battery connection.
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Thursday, June 9th, 2016 AT 5:40 AM
Tiny
CHEVYS10BLAZER43L
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The only way I can get it to start is by using a wire jumping off positive battery post to the ECM 1 fuse. When I do that it starts, but the throttle is stuck wide open for some reason.
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Thursday, June 9th, 2016 AT 5:43 AM
Tiny
CHEVYS10BLAZER43L
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My lowest compression for the plug wholes was 120 my highest was 160.
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Thursday, June 9th, 2016 AT 5:44 AM
Tiny
HMAC300
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There should not be any more than 20% variance in compression you are by passing computer is why it is probably going wide open. A professional should look at this.
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Thursday, June 9th, 2016 AT 5:52 AM
Tiny
CHEVYS10BLAZER43L
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Okay. I replaced spark plugs and wires. Ignition coil module and distributor cap the piece the wires plug into. What else could cause a no spark?
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Thursday, June 9th, 2016 AT 5:58 AM
Tiny
HMAC300
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I have answered all I can. I will leave this question open for another one of our experts to help you.
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Thursday, June 9th, 2016 AT 6:55 AM
Tiny
CHEVYS10BLAZER43L
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Okay, give me one more reply and I will leave you alone. I checked the compression and it ranged between 120-160 so 20% - 40% difference on a couple. What should I do to get compression between 20% like you said? With me changing the plugs, wires, ignition coil and distributor cap, what else could cause a no spark. What is the most effective way to check the fuel pressure? That is the last three questions I will ask you please please answer, and I will wont ask anymore questions.
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Thursday, June 9th, 2016 AT 7:26 AM
Tiny
HMAC300
  • MECHANIC
  • 48,601 POSTS
I have sent all that stuff aboutfuel pressure I thought auto parts rent gauge if it is got a couple of cylinders that are low and this was just overhauled take it back to who did it because something is wrong ro try readjusting the valves. if the coil wire has spark and no where else then I tmay be a bad rotor. if this vehicle is newere than a 1997 fuel pressure should be 60-66 psi at rail.

https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator
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Thursday, June 9th, 2016 AT 9:37 AM

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