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  1. #1

    Default Truck won't start after a few upgrades.

    Ok 1st a little history of what the truck has: 1990 GMC C1500 5.7L, MSD HEI Distributor, Hypertech Performance Chip.
    Now what I just finished adding is: Shorty Headers, Water Pump, Thermostat, Radiator, all new cooling\heater hoses, O2 sensor, spark plugs and wires, Edelbrock Valve Covers and Air Cleaner.

    Truck was running 100% before I installed all the new stuff and now it tries to start but it won't.
    You crank on it for a bit and it just blub-blub-blub, dies.

    I didn't mess with the distributor besides unplugging the wires, I've confirmed I'm getting fuel and spark.
    The tricky part is that the previous owner marked the dist. with a sharpie for the cylinder #'s but it doesn't match the firing order so it can't be right.

    I went ahead and wired the dist. to this layout:




    My brother is coming by with a timing light so we can check that to confirm and we'll also determine for sure which post on the dist. is #1.

    Any ideas regarding this problem please let me know. I was so careful not to mess with anything electrical related but regardless it won't start.

  2. #2
    Jr. Mechanic
    Join Date
    Mar 2013
    Location
    adirondacks,n.y.
    Posts
    113

    Default

    did you put plug wires back on the same way ?

  3. #3

    Default

    I would bet that your plug wires are not correct. If it ran the way he had it then even though he may have not had the numbers correct, it still ran. Your "correction" of the wires may be the issue.

    1995 Silverado 4x4
    6" BDS Suspension Lift-3" Body Lift-Add A Leaf in rear -Trailmaster SSV Shocks-Duel Steering Stabilizer Kit -AirAid Cold air intake-
    4.56 Gears with Detroit Auburn Locker-Pro-Comp Traction Bars with duel shocks-Aluminum Skid Plate Kit-38.5" x 16.5" Mickey Thompson Baja Claws-Constant Dropping fuel gauge

    2005 Yukon XL Jet Power Programmer, Bilstein Shocks, Bilstein rear springs, Helwig Anti-sway bars, EGR Window Visors, EGR Hood Shield, Denali Headlights, Headlight harness upgrade, GE NightHawk Bulbs, White Night Rear lighting system, Russell Braided SS brake lines, PowerStop Brake pads, PowerStop cross drilled and Slotted Rotors, http://www.gmtruckclub.com/forum/sho...5-GMC-Yukon-XL
    2002 Silverado ext cab 2wd (Sold)
    2003 Yukon XL (Totaled)

  4. #4

    Default

    I tried the plug wires both ways. The way he has it labeled cannot be correct. If the dist. turns clockwise and it's supposed to click by each cylinder based on the firing order 1,8,4,3,6,5,7,2 then there is no way his labels are right. There is only 1 # labeled in the proper location and that's plug 1. But even that is all based on the orientation of the dist. that I've seen from pictures. If #1 isn't really #1 then they would all be off from the get go. This evening we're going to pull the cap off so we can confirm #1 is for sure #1 and then wire accordingly.

    **If I can't get it running I will draw up an example of how he has it labeled which is different than the firing order.


    - - - Updated - - -

    1 thing I wanted to mention, when I have it wired the way it's labeled the truck won't even attempt to start. Wired the way the diagram above, the truck will at least blub-blub a little bit and the headers are warming up so I know it's firing. My assumption is that the post that he has labeled as #1 isn't actually that.

  5. #5

    Default

    Quote Originally Posted by CWBx View Post
    The way he has it labeled cannot be correct. If the dist. turns clockwise and it's supposed to click by each cylinder based on the firing order 1,8,4,3,6,5,7,2 then there is no way his labels are right. There is only 1 # labeled in the proper location and that's plug 1.
    .
    Even if his numbering was incorrect, it still ran. The diagram that you are using could be correct, but your distributor could be turned so that #1 in located where #8 or #2 is. It all depends on if the previous owner decided to advance or retard the timing for some reason. I would not move the actually distributor until you get it running again. If you do you could be compounding your issue, now you could have the timing way off and the wires incorrect. One rule of thumb that I use when I replace wires and a distributor cap is to place the new cap on the distributor, leaving the old cap laying next to it with the old wires still attached to the cap and plugs. Then I pull each wire off of the old cap, match the length, connect it to the corresponding post on the new distributor cap and to the same plug that the old wire runs to. With this method I have never had an issue with not having the wires in the correct place. If it ran before I replaced the wires I expect it to run after. I never try to figure out what someone else did, if it is running and running well, then they did what they did for a reason and it goes back together like it came apart.

  6. #6

    Default

    A quick way to find when #1 is tdc is to... pull the spark plug and thread a piece of paper towel into the whole. Then turn the engine over by hand with a wrench until the paper pops out from the compression stroke to tdc. Then watch the timing marks on the harmonic dampner and block until they align. This has always worked for my older 350 engines... and will give you an idea where number one is on via the rotor position. Now if it is in the incorrect position on the cap you can either change your wiring to match or pull the distributor and fix it. If you pull it you will want check/set the timing with a light.
    2009 Chevy Silverado 2500HDLT 6.0L w/ Towing Package, Dick Cepek GM8 Rims, Dick Cepek FC II 33X11.50R17,RKSport Ram-Air Hood(Functional), Lazer Lite Aluminum Tonneau Cover, Road Armor Stealth Bumper, PIAA Lighting, Diablo Trinity Tuner, Diablew Custom Tune, BullyDog Cold Air Intake, American Racing Headers w/highflow cats, Corsa Performance Sport Exhaust, Custom Striping, Black Bowties front and rear, Fuel Grille Inserts, Recon Headlights, Readylift Shocks, Readylift Upper Contol Arms, 2" Blocks in the Rear..

    Future Plans: HD Tie Rods, Under hood upgrades, Crower Camshaft and possibly electric fans.

  7. #7

    Default

    I totally understand what everyone is saying.
    I didn't realize the #ing was completely odd-ball compared to the firing order otherwise I would have paid extremely close attention to the route of each wire.

    This is not the 1st SBC v8 I've owned\worked on but it is the 1st that has ever given me problems.
    What gets me is why it won't run at least crappy unless every dang plug wire is incorrect. It's not backfiring it just won't run.

    I've also read about custom firing orders so maybe that's what he did.
    I'm for sure not going to pull the dist. out yet. I'm just going to find #1 by removing the cover in order to see the rotor following the technique TimTom listed.

    I left the P.O. a voice-mail so hopefully he'll respond and let me know why the dist. is labeled different from the firing sequence of the engine.

    Again, as soon as I get home I'll reply with the #'s he has written on the dist.

    Thanks again guys!

  8. #8
    Jr. Mechanic
    Join Date
    Mar 2013
    Location
    adirondacks,n.y.
    Posts
    113

    Default

    to #s on cap,is it cap for pretty routing of wires,i.e.exit same side as needed?cap will show routes other than straight up from post to post.little further in,could have 180 degrees out,no big deal,post back

  9. #9

    Default

    Ok so the way he has it labeled is: 1,2,7,3,4,5,6,8 / 1 being located on the drivers side front of the dist. *That's counting clockwise from #1.

    Anyone have an idea as to why it would be labeled that way?

  10. #10
    Jr. Mechanic
    Join Date
    Mar 2013
    Location
    adirondacks,n.y.
    Posts
    113

    Default

    got me,turn motor over by hand,put on mark at balancer,see where rotor is,on 1 like youre proper diagram you posted,or at 6,6 being 180 out

    - - - Updated - - -

    remember it takes 2 balencer cycles to one r.p.m.,hence the 4 stroke engine,pull a plug,crank motor , you will feel for compression stroke,on half cycle you will feel a smaller amount of air(exhaust stroke)check where rotor is,reinstall wires to rotor,dist. doesnt care where it starts from

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