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Major engine trouble.......need suggestions

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by mpascino, Dec 31, 2002.

  1. mpascino

    mpascino 1/2 ton status

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    This might get a little long, sorry, I am stumped and need to get home.

    Hi, not pretaining to my truck but still a gm, oldsmobile 350. Motor is outfitted with a bendix EFI system.
    Here is a list of what has been done so far:
    Valves checked and lapped into seats
    All seals/gaskets replaced
    Reman. crankshaft
    New bearings throughout
    Cam not replaced, but in good shape
    New oil pump and hydro lifters.

    This all started when my intake gasket went. I decided that I was going to do the top end of the motor since I knew the valves needed to be reseated. All is well, begin the trip home for the holidays. Timing gear decided it can't go on in this life on the highway. Takes out my oil pump....bye bye crank shaft. Also in the mist of this motor starts running like crap.

    All the work is done now and the motor is back in the car but it is still running crumby. If I pull the number 4 and or the number 8 spark plug or injector wires there is no change in engine rpm. All other cylinders react as expected. Normally a miss fire would come from an ignition problem or low compression. Compression is at 160-170 is EVERY cylinder. My distributor was rebuilt 6 months ago and the cap, rotor, and coil were replaced this morning. The car shakes real bad when it idles and lacks power. There is dual exhaust with no cross over pipes.... I can hear that the one side of the motor is not running smooth at all compared to the other. I am lost and running out of things to replace. I swaped the injectors around hopeing to find a bad one, but no change. I was supposed to be on my way back upstate already but I dont want to ruin anything after investing so much in this damn thing. Any advice or suggestions is greatly appreciated.
    Thanks and happy new year,
    Mike
     
  2. imiceman44

    imiceman44 1 ton status

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    Did you check that the sequence in plug wires is the right one?
    I had that once.
    You might have 2 crossed.
    Dual exhaust without crossover works fine, you only get better performance with it.
    Did you check the vacuum hose routing?
    Check it you might have some not hooked or mismatched.
    I still bet on the plug wires being in the wrong place, although not more than 2 in the wrong place.
    One more thing, do you have that valve on one side of the exhaust? I forget the name of that thing. It could be stuck closed.
    /forums/images/graemlins/thumb.gif
     
  3. mpascino

    mpascino 1/2 ton status

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    Hey, thanks for the reply. Yes I did check the firing order several times. I've been there before.... /forums/images/graemlins/crazy.gif The motor is a 1978 that I installed in my caddy. There are maybe 4 vaccume hoses at most. Don't have the exhaust pressure valve thing, no polution control equipment other than the EFI. I'll keep everyone informed.
    Thanks,
    Mike
     
  4. imiceman44

    imiceman44 1 ton status

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    Sorry I just noticed the EFI part.
    Is it TBI or TPI?
    Check for proper fuel pressure. For TBI I think 7-12 should be fine, for TPI you will need in the neighbourhood of 45PSI.
    Not enough pressure will make a poor running engine.
     
  5. u2slow

    u2slow 1/2 ton status

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    Is that one of those engines with the 4-6-8 system? (GM's revolutionary system of cutting out cylinders while cruising to increase economy).

    Anyway, they had a recall on this stuff, consisting of a fix to eliminate this feture. Since you're missing on 4 and 8, and I'm not sure what the firing order is, maybe its stuck in 6-cylinder mode?

    Its a longshot, but what the heck /forums/images/graemlins/wink.gif
     
  6. imiceman44

    imiceman44 1 ton status

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    NOPE.
    The only engine that had that was the Cadilac 6.0l fuel injected, 81 and 82 only.
    I had one of those 82 models and I can tell you I wish they didn't kill it. It was the best I ever drove and great milage to boot.
    I made a trip with it loaded to the gills so much that it was slammed to the ground, from Jersey to Califonia and got 24MPG.
    With a 6.0l = 365CI? and a TH400 that is great in my book.
    Too bad my sister destroyed it in an Accident.
     
  7. mpascino

    mpascino 1/2 ton status

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    Fuel pressure is at 39 psi, factory spec.... I'm clueless....
     
  8. mpascino

    mpascino 1/2 ton status

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    Nope, actually the car is an 1985 FWD Seville. I have this habbit of been different and decided to build a FWD machine. Longitudinal V-8s are fun /forums/images/graemlins/smirk.gif. What makes this situation even worse is the 8.2 liter I am building to put in this thing. I wasn't planning on dumping all this time/money into the 350. Live and learn I guess.
    Thanks,
    Mike
     

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