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New Engine Start-up: Help!

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by Chili 87 K5, Jan 1, 2001.

  1. Chili 87 K5

    Chili 87 K5 Registered Member

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    OK, maybe I'm missing something. I've rebuilt and reinstalled my 350 because of a broken crankshaft. All the pieces are back in, and there are no "mystery connectors". It cranks energetically, but won't fire.
    I've reinstalled the distributor and triple-checked the timing to 4 degrees BTDC. I'm getting fuel through the injectors and spark at the plugs.

    What's the deal? Any suggestions?

    Thanks!
    Chili
     
  2. wi86blazer

    wi86blazer Registered Member

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    Just a thought, it is possible that the distributor is off 180 degrees...
     
  3. 90K5

    90K5 1/2 ton status

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    Check the ignition module. You can get it tested at any auto parts store. if its bad, the engine will crank, but it wont spark, so it won't fire. I hope this helps.

    90K5

    See my truck at <A target="_blank" HREF=http://albums.photopoint.com/j/Albumindex?u=1329584&a=9886502>http://albums.photopoint.com/j/Albumindex?u=1329584&a=9886502</A>
     
  4. Smitty

    Smitty 1/2 ton status

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    Is the engine backfiring at all while you're cranking?

    Smitty
     
  5. Butch

    Butch 1/2 ton status

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    Who timed the camshaft? Are you sure the timing marks were lined up when you installed it? Also how do you have the wires hooked up to the solenoid on the starter. If you have them all hooked to switch side then when you let off from the start position it will kill the power to the distributor.

    I thought I was wrong once,
    but I was mistaken
     
  6. Chili 87 K5

    Chili 87 K5 Registered Member

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    Answers, in order:
    I had an assistant watch the rocker arms while I brought #1 to TDC... assuming my manual is correct, and the front valve on #1 is Exhaust, while the rear #1 valve is Intake. Before final approach to TDC, the intake (rearward) valve closed, which should mean it came to full compression at TDC, right? This should represent a fully-compressed fuel charge ready to burn. That's when I planted the distributor and marked the #1 post. During cranking, the timing light flashes just a hair BTDC;
    I am getting live spark from the coil and at the plugs (I checked them myself, while holding them to ground while cranking) plus, the inductive timing light is flashing;
    There was some backfiring BEFORE I pulled and reinstalled the distributor, as above, but not any more (it was 180 out, I think);
    I rebuilt the whole thing myself. When I installed the timing gears and chain, it was pretty clearly working properly. The timing marks aligned perfectly, and I hand-cranked it through several revolutions to be sure it was synchronized correctly. Also, the starter wiring has the battery/alternator lead to the large-diameter solenoid post, and the small-gauge ignition wire is attached to the opposite (small-diameter) post. I don't even get firing during cranking, though.

    Thanks for the tips, all! Anyone else???

    Chili
     
  7. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    Your intake valve should be closed before the piston even comes up on the compression stroke. I think your assistant was watching the wrong valve. If one of the valves is closing just before TDC it would be exhaust.
    4 stroke: Suck, Squeeze, Bang, Blow.
    If you are on the compression stroke BDC, the intake valve is already closed and will stay closed past BDC. If you are 180 out the exhaust valve is just closing right before TDC and the intake valve will begin to open soon.
    To me it sounds as if you are still 180 degrees out.

    Rene

    [​IMG]
     
  8. chevydude

    chevydude Registered Member

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    you might try static timinng
    to do this set #1 4degrees before tdc(or whatever you want to set your ignition timing at) then with your key turned on slowly rotate your distributor until #1 plug fires(make sure you got it grounded against the block) thats all there is to it its simple and foolproof,which means it works for me , oh yeah dont forget to snug your distrbutor up

    marcus
     
  9. Smitty

    Smitty 1/2 ton status

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    Another way to make sure it's on the compression stroke is to pull the #1 plug (Left front on a chev) and feel for compression as the engine is bumped. As soon as you feel compression align the timing marks and install the distributer. Only problem I've run into with this method has been a slipped ring on the harmonic balancer, took me forever to figure out that one out.

    Try not to get to frustrated with the folks on the list since you have the advantage of being on the scene and knowing how the engine is acting. The rest of us are just guessing at best.

    Good luck on getting it started.


    Smitty
     
  10. Thumper

    Thumper 1/2 ton status

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    OK, I did the same thing. I tried and tried to start the thing and it would not catch. Heres my question. How did you set your valves? By the book before you tried to start it? If so, you will have to pull the covers and back all the rockers off a bit, then give it a shot. The way the book tells you to adjust them doesnt work. They say to tighten the nut till the pushrod doesnt rotate freely anymore, but when you crank the motor over, the oil pressure pumps the lifters up thus opening the valves too far and you dont get any compression in the cylinders. I traced the whole thing when I rebuilt mine, and thats what I came up with. I had spark at the plugs, I had fuel on the plugs, but when I cranked it with my thumb on the plug hole, there wasnt any compression.
    Give it a try, just my experience....

    Good Luck
    Mike


    <font color=blue>Thumper
    85 Fullsize Jimmy
    [​IMG]
    <font color=red>Lets Go Wheelin! </font color=red>
     
  11. coopertwpk

    coopertwpk 1/2 ton status

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    is this aTBI motor?If so check your oil pressure sender wire the TBI motors have a low oil pressure fuel pump kill.
     
  12. Thumper

    Thumper 1/2 ton status

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    I almost forgot, if the problem is the valve adjustment, you will have to readjust them again, but I find the best way is while its running, tighten the rocker until each rocker arm stops rattling, then go 1/4 turn more. That will work dandy!

    Let us know.

    Mike


    <font color=blue>Thumper
    85 Fullsize Jimmy
    [​IMG]
    <font color=red>Lets Go Wheelin! </font color=red>
     
  13. Smitty

    Smitty 1/2 ton status

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    Makes sense. I adjust the smallblocks until there is no gap between the rocker and valve stem and then do a final adjustment while running.

    Smitty
     
  14. Wheels

    Wheels 1/2 ton status

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    Just out of curiosity, did you change the timing cover or the harmonic balancer? The balancers are indexed to match the timing tab on the timing chain cover.
     
  15. Grim-Reaper

    Grim-Reaper 3/4 ton status Author

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    Your 180 out. When you install the timming chain it puts the distributor 180deg out (crank rotates 2 times for every revolution of the cam). To be TDC both dots should be at 12 oclock. You need to turn the crank one more time then install the distributor on #1. Now you may have flooded the engine out and fouled the plugs. Pull them and clean them with carb cleaner and let them dry. Should fire right up.

    Diging it in the dirt with my K5's
    Grim-Reaper
    <A target="_blank" HREF=http://grimsk5s.coloradok5.com/>http://grimsk5s.coloradok5.com/</A>
     
  16. HarryH3

    HarryH3 1 ton status Author

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    The oil pressure switch in the fuel pump circuit is overridden during cranking. There's a fuel pump relay that sends power to the pump while cranking. Otherwise the engine wouldn't start until the starter had spun it long enough to build up oil pressure.

    <font color=black>HarryH3 - '75 K5</font color=black>
    <A target="_blank" HREF=http://ThunderTruck.ColoradoK5.com>http://ThunderTruck.ColoradoK5.com</A>
     
  17. Chili 87 K5

    Chili 87 K5 Registered Member

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    Roger that, everybody! I totally appreciate everyone's .02! It is really hard to diagnose an engine you can't see... and I'm used to working with "professional" customer service people that are really ignorant; YOU GUYS ARE WAAAAAY BETTER! Prob'ly 'cause you want to be, not 'cause you're making minimum for it! (Group hug, extra Budweiser all around!)

    Anyhow, the #1 intake closes well before TDC, so I'm pretty comfy with that. I WILL try static timing, and the BIG nod goes to THUMPER for the tip on the rocker adjustment! I'd heard that the "by the book" procedure left the valve too tight, but never from anyone trustworthy or with any "real" experience.

    I'll keep ya's posted on the outcome, and if I can get some pics posted, I'll show you my new mill!

    Blood and Guts,
    Chili
     
  18. lukers

    lukers Registered Member

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    Did it start yet?????
    Lukers
     

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