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94 gmc sierra no spark


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dr.donut
User

Jul 2, 2021, 8:08 AM

Post #1 of 11 (330 views)
  post locked   94 gmc sierra no spark  

94 gmc 1500 with a 305 , I had rough starts and once it did it ran fine , I replaced the coil with an ac delco and it fired right up when done . The next morning all it did was crank . I got the spark tester on one wire and got nothing . I imagine there's a ignition module under the distributor I can replace , should it be tested ? Is there something else I should look into ? Thanks.


dr.donut
User

Jul 2, 2021, 8:17 AM

Post #2 of 11 (325 views)
  post locked   Re: 94 gmc sierra no spark  

I was just checking the old coil and got 8,000 ohms ( 7,900 ) between the plug wire and all other connections , did that burn something out ? How could it even run when I moved it to replace that coil ?


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Jul 2, 2021, 9:42 AM

Post #3 of 11 (313 views)
  post locked   Re: 94 gmc sierra no spark  

That resistance is within the normal range for the secondary. The module operates the primary side which should be between .5 and 2 ohms. I assume you have an HEI distributor. There is an internal module and they burn out a lot. Low coil resistance can do that.



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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



dr.donut
User

Jul 2, 2021, 11:18 AM

Post #4 of 11 (298 views)
  post locked   Re: 94 gmc sierra no spark  

When it stops raining I'll get the new one in . Thanks , I'll assume the coil is internally grounded and that's where some of the continuity was from .


Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

Jul 2, 2021, 11:28 AM

Post #5 of 11 (296 views)
  post locked   Re: 94 gmc sierra no spark  

? Doc, is it HEI with coil in/on the distributor cap? It's grounded right there see metal and wire to ground. There can be a couple modules inside (easy job) count wires, 4 or 5 and bring it with you if worried about a match. Just don't bust the plug-ins for the thing if old, brittle,
Tom



dr.donut
User

Jul 3, 2021, 12:15 PM

Post #6 of 11 (266 views)
  post locked   Re: 94 gmc sierra no spark  

The coil is separate from the distributor and sits right in front of it , it has two sets of red & white wires , one set goes to the distributor and the other goes to the ecm I believe ., The distributor doesn't look like the hei I remember , it looks pretty standard , the parts clerk didn't have a bunch of questions when I got the module so it may be the correct one , but I won't know till I get the distributor off . Tiny little corroded screws , not like the good ol' days .


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Jul 3, 2021, 12:53 PM

Post #7 of 11 (262 views)
  post locked   Re: 94 gmc sierra no spark  

No, you don't have HEI.

The coil is NOT connected to the ECM. The Ignition module is. You have distributor on one side and power supply on the other.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



Tom Greenleaf
Ultimate Carjunky / Moderator
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Jul 3, 2021, 12:55 PM

Post #8 of 11 (260 views)
  post locked   Re: 94 gmc sierra no spark  

Spray those screws, PB and try not to bust them.
Oddly I don't recall this one. Coils, separate from "distributors" are grounded body of the things with a strap to known ground.

When if cap off look for a rotor and damage to it. It may have a spring loaded, carbon pile poker thing that touches the rotor?

Should have a fork hold-down at base of distributor, clean that off well and index right where it was, shaft to engine metal. Use even paper "Wite Out" for correcting typos - miss that stuff.

Rotor will turn when you lift out so note which way it went. Mark where you starter > which way it was pointing and another mark the back side so going back in can get real close.

IDK 94 was funky. If you don't get the cap off to see this is that much harder.

Question as I don't know! Are there timing marks on the lower damper/harmonic balancer are faint if there. Super fine wet/dry sandpaper and rotate by crank bolt or get underside to see them.

Stickers OE hope are still there saying what you do OMG would be a timing light unheard of for the most part. Do you have one?

Guessing when spark restored can be done not recommended to leave that way. Awaiting answers before my own fussy laptop behaves see what I can find about this exact set up?

Tom



Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Jul 3, 2021, 3:28 PM

Post #9 of 11 (255 views)
  post locked   Re: 94 gmc sierra no spark  

No, ignition coils do not require a ground. If there is a ground wire attached to the bracket, it is for the whole engine.

Try not to remove or turn this distributor. If you do, you have to locate and disconnect the timing connector to be able to set the timing.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



dr.donut
User

Jul 4, 2021, 12:00 PM

Post #10 of 11 (215 views)
  post locked   Re: 94 gmc sierra no spark  

I got the new module in and it fired right up , I'm sure it will in the morning too . One of the tiny corroded screws broke but I prevailed , I went as easy as I could . I didn't think it was HEI , didn't pay much attention to where wires went or what farmboi said on U-TOOB I only wanted it to run . I'm getting too old for this shtuff . Happy forth


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Jul 4, 2021, 12:31 PM

Post #11 of 11 (213 views)
  post locked   Re: 94 gmc sierra no spark  

Glad you got it resolved.

Closing this now as solved



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.







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