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Stranded again, What the heck ??

Discussion in 'Chevy Trucks' started by ronj, Dec 2, 2005.

  1. ronj

    ronj Junior Member
    from mn
    Messages: 21

    '87 Blazer, 305, auto, 155,000 miles used mostky for plowing my own driveway & occationally 5 mile commute to work. After sitting a couple months this is what happens..... Drive 5 miles to town, let it run while pumping gas & it dies. Will not re-start. A few hous later it does start, but does the same thing. I've owned for 12 years & have replace tranny twice, transfer case, heater core etc. I know her top to bottom but this don't make any sense. I did replace temp sensor on intake manifold & O2 sensor in Y pipe, no difference. One guy says maybe clogged exhaust, mice ?? Any ideas ??
  2. Bowlerdude

    Bowlerdude Junior Member
    Messages: 24

    Sounds like the ignition, check the coil. I have seen Coils that are broken function when cold but once the engine begins to warm up the coil starts to expand and the electrical connection is broken and no more spark.

  3. snowbankr

    snowbankr Member
    Messages: 49

    If/when the next time it happpens, tap the center of the gas tank...if this fixes the problem...time to drop the tank and replace the fuel pump. This only happens when the tank is full. Happened to me 5 times in 9 years on different Chevys, GMCs.

    Hope this helps
  4. karl klein

    karl klein Senior Member
    Messages: 557

    i think you should invest in a chaep 5.00 clear fuel filter and it will elemenate 1/2 of the possabiltys you can tell either fuel or elec.
  5. Blackwin

    Blackwin Member
    Messages: 58

    I had a same thing happen. To a Jeep CJ.

    Was as Bowlerdude said. Once I replaced the coil problem went away.
  6. wagonman76

    wagonman76 Senior Member
    Messages: 107

    Ditto. My moneys on the same thing. Ive had this happen with several vehicles. Bad ignition coil or control module.

    But first thing you should determine is whether it is a fuel or spark problem. Pick yourself up a spark tester and when it is not starting, see if there is spark. Or what Ive done is just pull a plug wire, put a spare spark plug in it, and set it up so I can see if it is sparking or not when I crank it.
  7. Detroitdan

    Detroitdan PlowSite.com Addict
    Messages: 1,937

    yup, coil or fuel pump. I forget, was the pump in the tank in 87? If it's mechanical on the block then I'd say it is definitely the coil. The GMs are known for in tank pump failures.
  8. Oshkosh

    Oshkosh PlowSite.com Addict
    Messages: 1,655

    Isnt there a pickup module in the Distributor?

    Hi, It has been a while since I've had to repair a Chevy, but didnt chevy have an issue with a module in the distributor a while back that would go bad???
    Just a thought, I know it was common just cannot remember in what.
  9. bigjoe871

    bigjoe871 Senior Member
    Messages: 166

    I had both an '87 and an '86 blazer. One had a 350 and one had the 305. Both needed to have the ignition module replaced INSIDE THE DISTRIBUTOR CAP. It was cheap and easy and both of them would run until warm then run rough then just die as they got up to temperature.

    Good luck.
  10. icebladez

    icebladez Member
    from sask
    Messages: 74

    ...and if it still persists..don't forget about those pesky EGR'valves..
  11. derekbroerse

    derekbroerse 2000 Club Member
    Messages: 2,377

    86's and 87's would have two different setups (not to say they wouldn't have the same problem).

    Up to '86 the trucks are carbureted, and use (more or less) the same distributor back to '75, the GM HEI. Fuel pump is mounted on the block. Not related, but '86 was the first year for the one-piece seal engine block.

    '87 was a year for major changes. The trucks all went TBI instead of carb. This meant in-tank electric pumps and "new style" HEI with external coil and computer control and knock sensor. Also not related, but of note, '87 was the first year for center-bolt valve covers and the modified intake bolt pattern.

    All of the above solutions are possibilities with these trucks. The simplest to check quickly is fuel--when it happens either dump a little gas or spray some ether in the intake and if it fires you know it could very well be a fuel issue. I've had problems with filters (even with the paper inside deteriorating and plugging itself up), the in-tank pumps (never buy aftermarket ones), and the wiring leading to the pump.

    Clogged exhaust is a little harder to test. It can be done with pressure guages but is a lot of work. If it is rotten just replace it and see, or take it down and try it out... even with a temporary piece of pipe and muffler.

    Electrical issues are much harder to determine. With the older stuff, you either had spark or you didn't... however from my own experiences with these trucks, you may well have spark but it may still not run. Or it will run and throw codes constantly.

    Personally, I'd start with the fuel test. Sounds an awful lot like a dying pump or something starving it.

    BTW, why are you letting it run while pumping gas? Isn't that illegal, like, everywhere?
  12. bigjoe871

    bigjoe871 Senior Member
    Messages: 166

    OK, the '87 had the ignition module replaced (got confirmation from my bro) and the 86 had a fuel pump and a new distributor. Sorry if I confused anyone.
  13. ronj

    ronj Junior Member
    from mn
    Messages: 21

    Sounds like everyone is leaning toward electrical....

    I pulled it in my garage lat night (after sitting about a month) ran really rough as usuall, I noticed & remebered a few more symptoms...... the check engine light comes on almost immedietly, the exhaust smells really gassy, unburned fuel ? from weak or limited spark ? Also leading up to this when a buddy borrowed it he commented on start up, how long the motor turned over before it fired. Thank you so much for all the feedback... gonna fire up the wood stove, turn on the Vikings & crack open the beer at the crack of noon & start lookin "er over

    Small "one mechanic town"

    Do it yourself or die trying.....
  14. GetMore

    GetMore Senior Member
    Messages: 179

    That sounds like it may be an injector problem. (You do have the TBI, right?)
    Ignition tends to just cut out, sometimes while you drive, and O2 probably wouldn't trip the CEL.
    As a matter of fact, on that early a truck the ECU is in open loop at startup, so that eliminates the O2 sensor. It does sound to me like one of the two injectors is stuck. With the air cleaner off and the engine running (or being cranked by a helper) you should be able to see the injectors fire.
    My experience with a dying fuel pump was that I would get power when I stepped on the gas, but it would die back within a second or two, so this doesn't quite sound like a bad pump.
    Oh, it might also be the fuel pressure regulator.

  15. NJBuickRacer

    NJBuickRacer Member
    Messages: 59

    When it dies, try spraying some carb cleaner into the throttle body and see if it will start and die. If it does, start looking towards the fuel system. If it doesn't start, pull the coil wire and check for spark. If it has no spark it could be the coil or module as suggested above, or possibly a distributor assembly(easier than changing pickup&reluctor yourself). I've had a few with hairline cracks in the reluctor ring that would not allow the pickup to see a signal below 550 RPM or so, makes for an interesting time troubleshooting:dizzy:
  16. derekbroerse

    derekbroerse 2000 Club Member
    Messages: 2,377

    First off, what trouble code is it giving? That is the very first thing we need to know before we can help with anything.
  17. ronj

    ronj Junior Member
    from mn
    Messages: 21

    Trouble code

    Trouble code continuously shows 12

    Also, Yes it is TBI
  18. NJBuickRacer

    NJBuickRacer Member
    Messages: 59

    Code 12 with the engine not running is normal, check what I described above.
  19. derekbroerse

    derekbroerse 2000 Club Member
    Messages: 2,377

    If it gives a code 12 WITH the engine running, it seems to me it had to do with the feed to the distributor. Back to electrical...