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Diesel questions

Discussion in 'The Garage' started by merace19, Sep 21, 2003.

  1. merace19

    merace19 1/2 ton status

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    I would post this in the diesel section but i am not a paying member yet. I have a 86 chevy blazer prior military. It has 6.2 with only 24k miles. I have a problem with hard starts. If i dont crank it in a couple days it is very hard to get started. Here is what i have done to test it. I have removed the line coming from the fuel lift pump and placed it in a 12 oz bottle. I cranked engine about 2 seconds and checked the bottle which now had about 1/3 full of fuel. I done this before and after the filter with same results. When the engine does start only the right side has any smoke come from it. But once running it is smooth and truck runns out fine with plenty of power, and no problem doing starts for the rest of the day. I have tested the ohms on the glow plugs and got a reading of .5 on most. I tested the voltage to the glow plug relay and got 12.89 volts. I have not changed the filter but have drained it to see if there could be problem with it. I have checked all lines as best i can. When i got it i drove it 900 miles to get it home with no problems, so i have new fuel in the tank. How do i test the fuel lift pump? or did i do it correctly but the pump was weak? I do bleed the air out using the air bleed on the side of the filter. Also what is the max speed i can go with the truck and not hurt motor? The dash has 55mph as max for Highway driving but i know that aint right.
     
  2. BlueBlazer

    BlueBlazer 1/2 ton status

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    Most likely glowplugs or slow cranking speed.
     
  3. merace19

    merace19 1/2 ton status

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    Why you say glow plugs? They tested out ok as far the ohm test. Hell i can guess at it. Cranking speed is good. batteries are hot so i ruled that out. I want facts or experiance to back up what is said. Im willing to listen to how you came about your answer.
    BlueBlazer62 I saw that you have Cat avatar so I am assuming you have experiance to back up what you said but humor me on why?



    (Guy ask me why his truck was driving funny, it started this morning. He said it was going all over the place on the highway. But when in town driving it was ok. His rear passenger tire was about to be completly flat. But i could have told him his shocks where bad) see what i mean? /forums/images/graemlins/thinking.gif
     
  4. doctor4x4

    doctor4x4 1/2 ton status

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    well im putting my $$$ on fuel delivery
    yea sound like your lift pump is working but it takes awhile to get the fuel all the way to the injectors if its not sitting there waitin as it sound like the fuel is back draining with time i recomend hook up a inline LOW PRESSURE DELIVERY electric pump with a switch and just flip the switch for 1 or 2 minutes before and during the starting process then shut it off once its starts and
    also are ya getting power to the timing advance ???
    and even if the glow plugs test well (and how did ya test em ) ?? doesnt mean there getting juce as the thermo controller is by far the weakest link on the 6.2 in my experience
    but i agree probaly not a glow plug problem as it does eventuatally start
    also check all the fuel lines for small cracks or breaks and play it safe replace any that even might be bad

    good luck
    & if im right your fee just is 25.00 big ones sent to steve for membership so we can welcome you on the diesel forum :-)
     
  5. Can Can

    Can Can Pusher Man Staff Member Super Moderator

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    I agree with BB62 that it could be glow plug related, but I'm leaning more towards a fuel line problem. I had some similar issues and it ended up being a slightly loose hose clamp at the lift pump. Make sure that no air is getting into the fuel system anywhere.

    It could also be caused by a bad diaphragm in your lift pump that is allowing your fuel to drain back if the truck sits for a while.
     
  6. BlueBlazer

    BlueBlazer 1/2 ton status

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    You say only the right side has smoke coming from it? White smoke I assume. This means that that bank has at least one problematic cylinder in it. White smoke is from trying to burn fuel at low cylinder temps. This means that either you have a bad glowlug, a cylinder low on compession, or possibly air in the system somewhere that only shows up on that bank for some reason. Is there any visible fuel leaks that could be drawing in air? The fact that you said if it sits for a couple of days and then is hard to start leads me to believe this might be a problem since it might take a couple of days for the pump to lose prime.
     
  7. merace19

    merace19 1/2 ton status

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    No leaks that i can see. Is there a one way valve in the fuel lift pump that can be leaking allowing the fuel to drain back down to tank? Im really leaning toward that thing as it controls the fuel up to the injector pump. And fact that it cranks right up during the coarse of the day. I do respect all the advice i am being Given. I know knowledge is hard learned and lessons given for free should be repected. I raced cars way to long not to understand when someone gives good advice and i not heed it.
    The amount of fuel that i collected during my test of the F.L.P. seems a little small. 3to4 oz's in 2 seconds? And the engine cranked up when i did the test, so i had to shut it down. I did not know i could pull that pink wire and the engine would not run.

    I tested the glow plugs using a volt/ohm meter as stated on a military maintance website. http://www.geocities.com/MotorCity/Highway/3969/glowdiag.htm
     

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