But does have spark in the run position?

Tiny
BUBBACHEVY
  • MEMBER
  • 2000 CHEVROLET SILVERADO
  • V8
  • 4WD
  • AUTOMATIC
  • 160,000 MILES
Silverado k2500hd - cranks, but has no spark when the key is in the start position, but does have spark in the run position. Any ideas?
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Monday, January 19th, 2009 AT 12:24 PM

6 Replies

Tiny
BRIAN 1
  • MEMBER
Check for any codes and if you have or can use a scan tool check cranking RPM and see if it is reading some sort of RPM. No spark when cranking could possibly be a crank position sensor. But check for any theft codes or pcm codes first and post back.
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Wednesday, September 2nd, 2020 AT 2:18 PM
Tiny
JDL
  • EXPERT
Hi, are you saying you have no primary voltage at the cop coils, with the engine cranking? I don't think you can have spark at the plugs with the key in the run position, when the vehicle won't start. Maybe I misunderstood?

It is possible to have more voltage available at key on than is available with engine cranking. Injector fuse A and B supply voltage to the cop coils and injectors. Those fuse circuits go hot with the key in the crank or run position. You need to check the fuse circuits with a test lite. Right now, I believe your saying, you don't have any primary voltage at the coils or injectors, with the engine cranking?
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Wednesday, September 2nd, 2020 AT 2:18 PM
Tiny
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Maybe I wasn't detailed enough in my description of the problem.

It doesn't happen every time I try to start the truck. It has happened twice in the last week, both times the overnight temp was around 10.

The first time the problem occurred, I tried holding the starter on for 10-15 seconds. When it didn't sound like it was going to start, I thought maybe the fuel pressure was low. I pressed the needle valve on the fuel rail and gas sprayed out. I don't have a pressure gauge, but the pressure looked sufficient. I Pulled a plug wire off and set it close to the block. I turned the key to the start position, held it there for 10 seconds and got no spark. When I let off of the starter and the key went to the run position, there was a spark between the plug wire and the block. I put the wire back on the plug and tried to start the truck again. Several times it would fire one or two cylinders when I turned the key from the crank position to the run position. After 15-20 tries, it started and ran fine. No problems starting it the rest of that day or the next few days. This morning, it wouldn't fire in the crank mode, but did when I let the key back to the run position. Only had to try about 5 times today.

As far as checking voltage at the coil, I haven't done that. There are no codes in the computer. I don't have a tool to check rpm, other than the dash mounted tachometer. I can't remember if it moved while the engine was cranking but not firing.
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Wednesday, September 2nd, 2020 AT 2:18 PM
Tiny
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I'm new here, and maybe I don't understand how the site works. I asked a question, but was not very detailed in describing the conditions under which the problen occures. I made a $10 donation and got a reply within an hour and a half. The reply was a need for more information. I posted back more than 24 hours ago and haven't received a response. Is a donation required for each post? How much is the average donation? Please respond. Thanks.
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Wednesday, September 2nd, 2020 AT 2:18 PM
Tiny
JDL
  • EXPERT
Hi, Me and Brian posted at the same time, he's a moderator. I thought he might have better info than me.

As far as the donations, I don't know much about that, I believe it will get your post looked at quicker.

Without a code or scan-tool data, it's hard to know where to look. I'd have to do some basic tests. I did ask about primary voltage at the coil connector. You said you hadn't checked it, yet.

If there is no rpm signal, Brian ask about that. You may not have any spark, no injector pulse, other than the initial prime, the pump may not run. I don't have your wiring diagram in front of me, if the pump circuit has an o/p switch in it, it is possible to have fuel pressure without an rpm signal. But the relay won't energize. I'll help anyway I can, but, you will have to do some of the testing.

I just wanted to add, if you have an injector pulse during cranking, then I think the rpm signal is present.
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Wednesday, September 2nd, 2020 AT 2:18 PM
Tiny
BRIAN 1
  • MEMBER
To answer your questions, donations the way they work is you dont have to donate if you do not want to, it will still get your question answered, if you do donate(which you did and we apperciate very much)gets attention to your question faster. We did not get your response because me and jbl123 posted at the exact time and sometimes you post back message is not recieved, it happens. Ive talk to the administrator or the web site about it and he is tring to fix it. If for some reason you are disatisfied with any answer you can ask for a refund and they will give it back. As far as your problem I will help as best I can.(A donation is not required for every post)now on to your problem, I need to know actual fuel pressure, pressing the needle valve on the rail is not a valid test, 2psi of fuel pressure will shoot across a room, you need a psi reading. The pressure should be between 55-62 PSI. Also the cam and crank sensor get there power from the pcm, it runs from the pcm to the crank sensor to the cam sensor then to the coils. No RPM no spark. Just start with the basics and post back an will advise from there.
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Wednesday, September 2nd, 2020 AT 2:18 PM

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