Engine is stalling

Discussion in 'Troubleshooting & Diagnosis' started by zekefreak, Aug 16, 2017.

  1. zekefreak

    zekefreak Veteran Member Lifetime Gold Member

    Apr 16, 2006
    western PA
    I'm having a problem with my 79 with a 350 engine and 700R4 trans that I can't solve and I hope someone here can give me some insight. While driving around town or on small trips to cruises my car runs fine with no issues. Last year while driving to a cruise 1 1/2 hours away on the interstate the car suddenly starts misfiring. Slowly at first and progressively get worse until the engine stalls. This happens usually in about 30 seconds. I pulled the car over on the berm and looked under the hood but didn't see anything wrong. I got back in, started it up and drove away like nothing happened. Ten miles down the road it did the same thing. Now it was a hot day and my engine was running about 220* so I'm thinking it was vapor lock. When I got home (it stalled two more times on the way home) I retarded the timing and the temps dropped to about 190* (on average days). The other day I took the car on the interstate and after about an hour it happened again. Started to miss and eventually died. Pulled over, waited 2 minutes and it fired up and drove off like nothing happened. Both times the car had been driving high speeds (75 mph) for about an hour. Again on local trips I have no issues. I have a MSD 6A ignition box so I called the tech and explained what was happening. After questioning my wiring, which I assured him was correct, he said that it isn't the ignition box because the unit would not "heal" itself by resting on the side of the road. I know the engine is mechanically sound and I don't think it is a fuel pump because it runs great after it restarts. Which leads me to think its an electrical problem. Any ideas or suggestions? Thanks
  2. Coadster32

    Coadster32 Veteran Member Lifetime Gold Member

    Oct 2, 2013
    If you think it may be vapor lock keep the gas cap loose, or when it happends immediatly take it off, and see if you get pressure release. Also, sometimes electrical componants will not work properly when overheated. When they cool down, they work fine. Condensors used to do that.
  3. 74BIBELOT

    74BIBELOT Veteran Member

    Could be a GAS problem, Most of the times electrical devices "cut" out inmmediatly while gas problems take more time.
    Check fuel related parts, gas tank, fuel pump and FILTER/s
  4. zekefreak

    zekefreak Veteran Member Lifetime Gold Member

    Apr 16, 2006
    western PA
    I did loosen the gas cap before my trip back home and it still stalled twice.
    Its hard for me to believe a fuel pump/filter would quit and then come back strong after a couple minutes. I'm thinking something in the MSD box is overheating and cutting out and then after it cools it starts working again. I have a spare 6A box that I'll put in. I'm just not sure I want to drive an hour away from home to test it. LOL!
  5. APEowner

    APEowner Veteran Member

    Dec 9, 2013
    Albuquerque, NM
    Does that still have an EGR valve? If so, it could be sticking open.
  6. zekefreak

    zekefreak Veteran Member Lifetime Gold Member

    Apr 16, 2006
    western PA
  7. rocket dawg

    rocket dawg Veteran Member

    May 5, 2015
    Grand Rapids Mi
    Vapor lock wont cure itself in 2 minutes. My understanding of vapor lock is gasoline boiling and creating air in the system. My 1958 ford tractor does this under heavy work load and it wont start until the engine cools for at least 30 minutes. The ford has a intake/exhaust manifold as one piece so running 15% ethanol gas makes it run hotter. Anyway I had an issue with my sbc that would leave me stranded on occasion. It had 2 different problems. 1. was the wrong fuel pump, but that would act up after I shut the car off--gas would drain back to the tank and I'd have to pour gas down the carb to get it to re-fire. 2nd was a blue printed HEI dizzy from Summit. It replaced a stock HEI. Driving, the engine would randomly die and not restart for hours. Happened while driving at any speed and no warning. I replaced most everything in that dizzy, --module--cap--rotor--coil-- still it kept dying on me. I dumped that dizzy and went with MSD 6A and the MSD billet dizzy, and MSD coil. I dont run vacuum, just mechanical-- I have never had a problem since. My best guess is the ignition, but what part? coil? key? wiring? Which distributor are you running?
  8. zekefreak

    zekefreak Veteran Member Lifetime Gold Member

    Apr 16, 2006
    western PA
    I am running the stock distributor although I removed the module and hooked up the 6A.
  9. Zspoiler

    Zspoiler Veteran Member

    May 6, 2012
    Federal Way, Washington
    Have tried changing the gas filter or have extra with you. Do you have a stock gas cap?.Try the other stuff the other members have suggested.And get back to us.
  10. 80sz

    80sz Veteran Member

    Feb 2, 2014
    That's a hard one. Going over grounds ,battery connections tight,give a yank on battery cables ,I've had them become loose in the crimp connector causing a intermittent sputter. Check bowl sight screw when happens again to see if fuel is low?

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