Truck problem help

Discussion in 'Shop Talk' started by Rob30, Jan 5, 2007.

  1. Rob30

    Rob30 Well-Known Member Supporter

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    My 96 GM would not start today. It has spark and gas. I tried drying out the wires/cap/rotor because of the wet weather. Still nothing.
    I can't understand what is wrong. The engine turns over fine. No funny noises, except the odd small back fire, I figure it is from flooding.
    Any help
     
  2. Beeman

    Beeman Well-Known Member

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    96 GM What?
    When was the last time it ran and how did it run? How are you checking for gas or do you mean it has gas in the tank registering on the gauge? How are you checking for spark and where?
     

  3. Yeti

    Yeti Well-Known Member

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    just some things to check, if you take the cap off the distributor does the rotor go around? If not then you may have broke a timing chain. since its a fuel injected engine it should have a throttle body type injection, if so then you can check the spray pattern of gas by just watching it while someone cranks the engine. if the pattern looks week or is just a bunch of drips then the fuel filter could be plugged or the pump is bad.
     
  4. Rob30

    Rob30 Well-Known Member Supporter

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    It is a 1/2 ton truck.
    The gas I checked in the line where you attach a pressure gage. Lots of fuel squirted out.
    The spark I checked was from the #1 wire.
    It is a multiport injection. I can't see the spray.
     
  5. wilderness1989

    wilderness1989 Well-Known Member

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    In that case I'd check the fuel pump pressure at the fuel filter and replace the filter while that was being done. You might 1st pull a couple of plugs and check the compression. Someone you know should have a compression tester if you don't. You'll probably have to have a shop check the pump pressure. The pressure is quit high 40# or something like that and it will take a special gauge.
     
  6. Beeman

    Beeman Well-Known Member

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    Fuel squirting out isn't an accurate test, That vehicle requires about 60lbs. of fuel pressure. If you can't check the injectors you don't really know if the cylinders are getting fuel. You might be able to listen to the injectors by placing a long screwdriver gently against where the injectors are in the plenum and listen with your ear against the screwdriver while someone turns the engine over. You might possibly hear the clicking of the opening and closing of the injectors. If you got spark with a correct spark tester at the end of the #1 wire it proves the rotor is turning and your ignition is working.
    Hold the throttle body open and look in with a flashlite while someone cycles the key on and off to make the fuel pump run. See if there is any fuel spraying inside the plenum, there shouldn't be. if you see fuel spraying it usually is a bad fuel pressure regulator which is inside the plenum. Next remove the spark plugs and see if any are wet. If you find an extremely wet plug or plugs you have excess fuel from the above or stuck open injectors, a fuel pressure test with a gauge would show you this as the pressure would drop when the pump stopped showing leakage in the system. If you are getting wet plugs or see fuel in the plenum don't keep cycling the key or cranking the engine. you can lock the engine by filling the cylinder(s) with fuel. You will also be diluting the oil with fuel.

    How many miles and how well maintained is this truck? Were there any signs or symptoms before this happened or was it running like new and then this?
     
  7. farminghandyman

    farminghandyman Well-Known Member Supporter

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    if it has a crank shaft sensor it could be going bad,

    my mothers car was starting very hard, and I used a touch of starting fluid and it would start, it took the shop about three weeks of driving it to find the sensor, (or to have it fail on them when driving it), on me it was fail ever time I was away from home,
    and there were no codes being displayed,
     
  8. Oldguy

    Oldguy Well-Known Member

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    I had the same problem with my 98 blazer today, would turn over fine, wouldn't crank. I drained gas, added new gas, then poured a little into the throttle body since my injectors are in the plenum and it cranked right up ran a second then died. Did this 4 or 5 times and it started running with the new gas. It was water condensation buildup in the lines
     
  9. Rob30

    Rob30 Well-Known Member Supporter

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    I poured a little gas in the throtle body. The truck back fired. I let it sit over night. Tonight it gave a little back fire then it gave couple very little attemps at firing. I'll check the plugs tomorrow.
    Please tell me if I am wrong here;
    *It could be a sensor messing up the timing(crank or cam sensor)
    *It could be not enough fuel. Low pressure from plugged filter or weak pump.( I replaced the pump and filter about 6-8 months ago) However I do have to change the filter 1 or 2 times a year.
    *Water in the fuel lines.
    What about a timing chain. The truck does turn over well with no funny noises. Except the couple backfires. But that could be from the gas down the intake.
    The truck has been running fine. Very well maintained. 1 on going problem with a connection at the computer. But thats not the problem. I have noticed for a few months the valves 'rattle' when under load.
    If there is fuel on the plugs would that not mean the pressure is high enough?
     
  10. farminghandyman

    farminghandyman Well-Known Member Supporter

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    I doubt if this is the problem, but I have a little story to tell,
    one day I came home from town and pulled in to the drive way, and then we needed to move the truck (ford 400 engine), so I went to start it, it would just back fire and once and a wile would may be try to kick, then all a sudden there is this explosion under the truck and dirt and stuff filled the air, and came filled the yard with dust,
    the muffler blew up,
    the problem was the roll pin in the distributor has sheared and the distributor was not turning, (the plastic valve umbrellas to shed oil off the vale stems had disintegrated and got sucked in to the oil pump, and stuck the pump). the distributor would just bounce back and forth a little. and apparently the gas and air mixture was just going in to the exhaust system and then when the exhaust valve was open on a cylinder, the spark plug must have ignited the mixture, and boom, no more muffler.

    but if the timing chain or belt jumped a notch it could be doing what you describe,
     
  11. redgrizzly69

    redgrizzly69 Member

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    Your location says ontario, has it been warm up there like it has here in Minnesota, you may have a heck of a slug of water in you fuel line, warm days and cold nights always give you trouble with condensation.
     
  12. Hammer4

    Hammer4 Well-Known Member

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    How full was the tank? If it was pretty low and you had some warm days and cool damp nights you probably condensed a lot of water in there, get some heet or the equivalent and dump in there to try and get the water broken down if that is a possibility.

    My wifes car ( and another girls car I knew ) had the same problem, set for a few days in cold weather with near empty tanks, took a couple bottles of heet and jump starting and cranking to get them going....took em straight to fill them up along with a couple more bottles of heet.

    My Dad always was reminding me of that, to keep the tank as full as possible in cold weather to cut down on the air space for condensation.
     
  13. Rob30

    Rob30 Well-Known Member Supporter

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    The cap had a short in it. So I was getting spark, but at the wrong time.
     
  14. Old Vet

    Old Vet In Remembrance

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    Most of the time it is something simple to fix. I always check out the simpler things first.