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No spark

Tiny
JAMESGREEN
  • MEMBER
  • 1998 GMC JIMMY
  • 6 CYL
  • 4WD
  • AUTOMATIC
  • 200 MILES
98 gmc Jimmy, six cylinder vortec engine, lots of miles.
driving down the road car died. Fuel pump can be heard to run when ignition is turned on, all fuses appear to be fine. No spark from coil (changed coil still no spark), changed crank shaft position sensor still no spark. One oddity is that the fuel level gauge now doesn't work either, coincidence? Before taking the car to the local shop, any ideas? Somebody else told me that it is probably the pick up coil. Thank you
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Monday, May 30th, 2011 AT 7:19 PM

10 Replies

Tiny
JDL
  • MECHANIC
  • 16,098 POSTS
Take coil wire loose from distributor cap, hold close to engine ground, engine cranking, is there spark? How long since a tune-up? Cap--rotor--coil wire, among other.

Check for primary voltage at the coil, pink wire, goes hot with the key on. Use voltage tester. That voltage comes from ecm 1 fuse, underhood fuse block. Any applicable trouble codes?
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Monday, May 30th, 2011 AT 7:58 PM
Tiny
JDL
  • MECHANIC
  • 16,098 POSTS
I forgot to add, no pickup coil on this vehicle.
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Monday, May 30th, 2011 AT 8:03 PM
Tiny
JAMESGREEN
  • MEMBER
  • 9 POSTS
No spark from coil wire. Engine does crank. Long time since last tune-up (cap and rotor pretty trashed). Will change.

ECM 1 fuse 15 amp was blown, thank you very much. Will replace cap, rotor and wires before trying to run car. By the way do you know of a trick to get to the spark plug that is blocked by the steering rod? I have never changed this plug because I can't get a socket on it
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Monday, May 30th, 2011 AT 8:29 PM
Tiny
JDL
  • MECHANIC
  • 16,098 POSTS
That fuse supplies voltage to several circuits, it may just blow again? Hope not.

I'd have to look at the spark plug, I don't know any tricks. Some v engines it's easier for me to get at some plugs from underneath. That means safely raising and supporting the vehicle. There are safety issues with working under any vehicle.
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+1
Monday, May 30th, 2011 AT 8:42 PM
Tiny
JAMESGREEN
  • MEMBER
  • 9 POSTS
Replaced cap and rotor before trying to start car (replaced ECM 1 fuse). Car didn't start, checked fuse (blown)sigh. Not much information in chiltons book about wiring for this circuit. Is there a likely suspect in this circuit to check? (Hopefully). Thank you
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Tuesday, May 31st, 2011 AT 7:49 PM
Tiny
JDL
  • MECHANIC
  • 16,098 POSTS
Unplug the coil and ignition module, see if the fuse still blows. If it does, check the fuel injectors. If it is a wiring circuit problem, it's like hunting a needle in a haystack. Any applicable trouble codes?
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Tuesday, May 31st, 2011 AT 8:17 PM
Tiny
JAMESGREEN
  • MEMBER
  • 9 POSTS
Unplugged coil and ignition module, fuse remained good (suspect this is bad for me).
GMC dealership service department suggested a bad/going bad fuel pump.
I don't own a ocdb reader (or whatever their called now), remember tried using one when they first started to be used, didn't like it and have never tried again. I suspect that I should get over my initial trial of the technology and try again.
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Tuesday, May 31st, 2011 AT 9:01 PM
Tiny
JDL
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From the info I looked at, ecm B is for the fuel pump, not ecm 1. These are different fuses.

To check for codes, at the least, you need an obd2 code reader. Even that may not show anything? Some autostores can test ignition modules, don't know if they can test yours? You can call and ask.

Ask them if you can try a new coil and if it doesn't fix the problem, can you bring it back? Some places will let you bring it back, some won't. I haven't found an ohms spec on that coil, for testing?
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Tuesday, May 31st, 2011 AT 9:41 PM
Tiny
JAMESGREEN
  • MEMBER
  • 9 POSTS
Ign mod and old coil unplugged replaced fuse ign on fuse okay. Plugged in old coil turned ign on (blew fuse).
Installed new coil and fuse left coil and ign mod unplugged turned ign on, fuse okay.
Plugged in ign. Mod turned ign on (fuse okay).
Plugged in new coil turned on ign. (Blew fuse).
Does this narrow it done any? (Fingers crossed). Thank you
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-1
Tuesday, May 31st, 2011 AT 10:58 PM
Tiny
JDL
  • MECHANIC
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At this point, all I can do is hunt and peck. I don't know any way to test ignition module. If one item on that fuse circuit is drawing just a little too much, unplugging anything won't help, it just lowers the amp draw enough, not to blow the fuse.

I'd have to check the amp draw for everything on that fuse circuit, individually.
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Wednesday, June 1st, 2011 AT 12:20 AM

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