350 in my '79 dies randomly (just shuts off) - more details inside

Discussion in 'Troubleshooting & Diagnosis' started by AllensaurusRex, Apr 17, 2018.

  1. AllensaurusRex

    AllensaurusRex Veteran Member

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    Hey guys! I have a 1979 z28 with a nom Chevy 350. small cam, heads, etc. Everything built very mildly. Delco Remy distributor. I have probably put 500 miles on this car since I bought it and it has done great...even driving 2 hours at a time without shutting off from Alabama to Tennessee. Today it was 75 out (hottest day driving so far) so I took the ttops off and was driving home from work and it randomly shut off after about 25 minutes of driving on the interstate. No sputtering. Just lost all power. I was able to get it to turn back over while coasting about 50mph. Whew. I thought I may have just bumped the key with my leg or something. The dummy temp gauge read right around 210-220 when this happened. 5 minutes later I'm pulling into my driveway and it died again. I tried to get it to crank back but no luck. I didn't want to kill the battery so I gave it a rest. 10 minutes later, I tried again and fired up without issue. I let it idle for probably 30 minutes and the temp gauge never even got up to 210. I then took it out on a ride around the block and 5 minutes in, same thing. Luckily I could pull over. I waited 5 minutes and she cranked right back up. All 3 times this happened I was accelerating (even if just lightly into my driveway). I could not get it to die while idling.

    So I'm thinking possible ignition module/coil? Maybe a bad ground? Also heard the voltage regulator could cause this? Looking for leads. This is my Daily Driver so hoping someone has some expertise.

    Thanks!
     
  2. Billybad

    Billybad New Member

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    Have you checked for spark when it dies?
     
  3. AllensaurusRex

    AllensaurusRex Veteran Member

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    not yet. It will start back up almost right after. and idle without issue.
     
  4. 8pack

    8pack Veteran Member Lifetime Gold Member

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    Best guess is a bad ignition module/coil. Almost certainly electrical if it just flat out shuts down. Do you have a spare module/coil you can drop in?
     
  5. NeoNeuro

    NeoNeuro Veteran Member

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    I agree with 8pack, it's electrical. I had an Impala that would do the same thing. It had a faulty 12v power connection at the firewall. Everything would go dead except for the brake lights. Is it only the engine that dies or do other things quit working as well?
     
  6. Twisted_Metal

    Twisted_Metal Administrator Staff Member Lifetime Gold Member

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    Check the ground from the engine to the firewall.
     
  7. aggcamaro74

    aggcamaro74 Member

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    Check your battery cables. When I did my engine swap a few years ago that was the one thing we didn’t change and I started having the same problem. Come to find out one of them was grounding out randomly and killing all power to the car.
     
  8. AllensaurusRex

    AllensaurusRex Veteran Member

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    Thanks everyone. Here is some more insight:
    • The first time it died I was going about 50 on the interstate and lost everything. Power steering, power brakes, etc. I don't remember if the radio shut off, as I was trying not to die. haha. I do remember throwing it into neutral quickly and then turning the key. I also hit the gas a few times and wahlah, it cranked back over after about 3-5 seconds of coasting. Honestly, at this point, I thought maybe I had run out of gas. I had been driving about 25-30 minutes so far here, and it was the first day I had noticed the temp gauge was reading (I previously thought it was broken and was going to just get an after market one this week).
    • Pulling into my driveway about 5 minutes later, it died again. Everything shut off. No power brakes/steering, etc. Again, I don't remember if the radio shut off or anything. I just know I had lost all power to the car. This time, it cranked for about 3-4 seconds with no luck. I gave it a little gas too for another 4-5 second crank and no luck. I didn't want to kill the battery so I gave it a rest. I walked to the gas station and got 2 gallons of gas and came back and put it in. This time I do remember pumping the gas about 4 or 5 times when starting and WAHLAH, it started. At this point, I'm thinking...yup I'm an idiot and ran out of gas. I then drove up to the gas station 1 minute up the road and started filling it up and it only took 6 gallons. That's when I knew I didn't, in fact, run out of gas.
    • I brought it home and shut it down. 5 minutes later, I started it again without any issue and let it idle for ~30 minutes. It didn't die or hesitate at all here. The stock dummy temp gauge read right around 1/4 (well under 210) and I was in the shade. I tried my luck again...and drove about 1/2 mile up the road and everything shut off again. I pulled over...waited 5 minutes, and it started right back up. I made it home without issue.
    • This morning I went out (~12 hours after my last start), turned the key...and it fired right up.

    At this point I'm thinking a few things...I think it is clearly electrical since everything just completely shuts down...BUT, why wouldn't it just crank right back up immediately after dying some of the times? The times when I waited...and even this morning, it fired up perfectly. The other times, it cranked for while before firing.
    1. Bad ignition coil. I don't have another to drop in and have the delco remy kind that is in the distributor. Not an external coil. Can I grab just the coil at an Autozone? I'm assuimg its right under the dust cap? THIS is the distributor I have I believe...
    2. Ignition switch overheated. It looks reasonably easy to drop the column, and this part is cheap. Anyone heard of this happening before? I saw it on a forum or two.
    3. Bad ground somewhere. I'll investigate this more soon.
    THANK YOU EVERYONE. ANY AND ALL HELP IS APPRECIATED.
     
    Last edited: Apr 18, 2018
  9. 8pack

    8pack Veteran Member Lifetime Gold Member

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    It sounds like when the car gets hot it shots down. If you have a Bad Ignition module/coil heat sometimes they will work fine when cold but shut down when they get hot. I can't explain why sometimes it shuts off and you can immediately start it again except that if it is electrical and internal a million things could be happening that allow that to happen. It could be the ignition switch or the Neutral Safety Switch and since it is cheap and you wanted to try that first it couldn't hurt, but I would Start with the ignition .

    You might need to do some testing. Maybe bypass the NSS to see if it happens. If it still happens you eliminated that. Not sure how to test the Ignition switch and if the HEI Issues are heat related that is going to be tough to test for....Maybe someone can give you some pointers on testing.

    Unfortunately I tend to throw parts at things starting at where I think the most likely issue is. Don't go by me but I would do this in order, testing after each change......it is not a very cost effective way to solve the problem though....the napa parts below may not be the most cost effective but I tend to like them....

    1. Bypass NSS to eliminate that
    2. Replace ignition module
    3. Replace ignition switch
    4. replace coil

    ICM
    https://www.napaonline.com/en/p/ECHTP45

    Coil
    https://www.napaonline.com/en/p/ECHIC19

    Neutral Safety Switch
    https://www.napaonline.com/en/p/ECHNS6589

    Ignition Switch
    https://www.napaonline.com/en/p/ECHKS6622
     
    Last edited: Apr 18, 2018
  10. Bandit723

    Bandit723 Veteran Member

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    So when you say "I think it is clearly electrical since everything just completely shuts down"
    I am assuming that nothing electrical works then? no headlights, door lights etc... then I would start looking for a bad ground or + feed to the car
     

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