Question about 1998 GMC Yukon

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1997 5.7L 4x4 chevy truck running bad

The truck was running bad and had alot of miles on it so we overhualed it and recon. the heads. Put the motor back in the truck with new plugs, plugwires,cap and rotor the truck runs the same as it did before the overhual. I checked for code and got a p1345 thats timing but i put a new crankshaft sensor in to. STILL RUNS THE SAME. I know the dist. needs to be set on #1 at TDC , it looks and smells as if it is flooding the motor and it doesn't clean up at a higher rpm. what could this be i'm about to pull my hair out please have the answer please thanks rick

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  • rdhomesoluti Jan 07, 2009

    Have good spark at the plugs anmd is the crankshaft sensor the only sensor that controls the fuel.

  • rdhomesoluti Jan 07, 2009

    cam was lined up and everything was good at the crank pick up. like i said the truck runs the same as it did before the overhual.

  • rdhomesoluti Jan 07, 2009

    the cam is lind up dot to dot like i said the truck runs the same as it did before the overhual. it ran with a miss in it and smells asif it is getting to much gas. what other sensors run the fuel flow.

  • rdhomesoluti Jan 07, 2009

    i was told that a 1997 chevy 5.7L did not have a cam sensor does it and what is the location of the sensor the crank sensor is new.

  • rdhomesoluti Jan 07, 2009

    Plugs are new along with the cap and rotor wires

  • rdhomesoluti Jan 07, 2009

    i was told that the 5.7L 1997 chevy does not have a cam sensor can any one tell me if it does and location of it

  • rdhomesoluti Jan 07, 2009

    does the exhaust solinoid control the fuel and the timing and how come i get no code on that at all. iring is clean no oil on themplug ends all look good

  • rdhomesoluti Jan 07, 2009

    plug gap is ok it ran the same with old plug and new ones

  • rdhomesoluti Jan 07, 2009

    it is if it getting to much fuel and i don't have a fual presser metter it smells like fuel is not being burnd

  • rdhomesoluti Jan 07, 2009

    why does the motor run as if the fuel is to muck on some banks and not any on other banks i can pull off the plug wires on 3-5-7 and it doesn't change how it runs at all. is this fuel presser.

  • rdhomesoluti Jan 07, 2009

    ya the old plugs looked black and the cylinder after pulling the heads was black and pistons looked clean in some cylinders like it was washed.

  • rdhomesoluti Jan 07, 2009

    i checked the timing and pulled the cap it is on # 1 timing mark is inline maybe its not getting fuel to some of the banks.

  • rdhomesoluti Jan 07, 2009

    new chain has a new exhaust a year a go

  • rdhomesoluti Jan 07, 2009

    will check fuel pump presser

  • rdhomesoluti Jan 07, 2009

    plug wires are all in order it ran the same way be for i overhualed the engine. so what ever is wrong with it it was doing it before it was overhualed.

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I own a 98 chev trk, it has a 350 motor.I have a problem with oil running out the tail pipe,could this be the valves.

Posted on Feb 15, 2009

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The whole thing looks still like a timing problem.

Among the other things you should do an ECU scan.

Posted on Jan 09, 2009

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  1. Disconnect the CMP sensor wiring harness and connect an LED test light between CMP harness terminal C and battery ground.
  2. With the ignition ON and the engine off, verify that the test light illuminates.
  3. If not as specified, repair or replace the fuse and/or wiring.
  4. Carefully connect the test light between CMP harness terminal A and C and verify that the test light illuminates.
  5. If not as specified, repair the CMP harness ground circuit (terminal A).
  6. Turn the ignition OFF and disconnect the test light.
  7. Next, connect suitable jumper wires between the CMP sensor and CMP sensor harness. Connect a DC volt meter to the jumper wire corresponding to CMP terminal B and battery ground.
  8. Start the engine and verify that the voltage signal is 5-7 volts.
  9. If it is not as specified, the CMP sensor may be faulty.
REMOVAL & INSTALLATION
  1. Disconnect the negative battery cable.
  2. Detach the sensor harness connector at the sensor.
  3. Unfasten the retaining bolt, then remove the sensor from the camshaft housing. Inspect the sensor O-ring for wear, cracks or leakage and replace if necessary.
To install:
  1. Lubricate the O-ring with clean engine oil, then place on the sensor. Install the sensor into the camshaft housing.
  2. Install the CMP sensor retaining bolt, then tighten to 88 inch lbs. (10 Nm).
  3. Attach the sensor harness connector.
  4. Connect the negative battery cable.1997 5.7L 4x4 chevy truck running bad - 20a90dd.jpga525940.jpg

Posted on Jan 07, 2009

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OK... i have read everything everybody is saying about this problemhere is my take on it.

I believe is the fuel pressure regulator. Pull the fuel pressure regulator vacuum line off and see if it makes it worse. If it does not make it worse, the vacuum line with your finger for vacuum. If you have vacuum on the line, replace the fuel pressure regulator. Fuel pressure in fuel injection runs from low at idle to high at wide open throttle using vacuum to regulate fuel flow. So if the fuel pressure regulator has failed to drop the pressure at idle it would be throwing way to much fuel into the engine at idle.

Hope this helps you out.

Mike

Posted on Jan 07, 2009

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I would say the most common problem is a clogged fuel filter. Make sure you follow your manufacturers recommendations as to when you should change the fuel filter. This information should be in your owners manual. Symptoms include sputtering at high speeds or engine not starting at all. Always check the ignition system first, if that's ok then the next suspect is the fuel filter.
Next most common problem is the fuel pump failing. Most modern electric fuel pumps can be heard when you turn the key on. If you don't hear the pump running and your car will not start, it could be your fuel pump. The first thing a mechanic will check is the relay which sends power to the pump. If this is operating correctly then the pump will have to be replaced.
Last but not least is dirty injectors. While the fuel filter does a good job of filtering the fuel, it's not perfect. Over time deposits and tiny particles lodge themselves in the injectors. This can clog and injector and prevent it from delivering the fuel the engine needs. It can also cause an injector to stick open and send too much fuel into the engine. A regular addition of fuel system cleaner like STP Injector Cleaner, or Techtron fuel system cleaner can help keep your injectors clean. Most gas stations, department stores and all automotive parts stores will have a good cleaner available. Add it to your empty tank right before you fill up and it will clean as you drive. I recommend doing this every 3 months to keep your injectors performing like new. Mechanics also offer a cleaning service where they actually disconnect the fuel line and flush cleaner through the engine. This is only necessary when you let your injectors get to a point where they can not be cleaned by a store-bought product. Regular use of a good in-tank cleaner will keep you from having to pay for this service.

Posted on Jan 07, 2009

  • Antonio Buenafe Jr.
    Antonio Buenafe Jr. Jan 07, 2009

    On newer cars
    the fuel pump is usually installed in the fuel tank. Older cars
    have the fuel pump attached to the engine or on the frame rail between
    the tank and the engine. If the pump is in the tank or on the frame
    rail then it is electric and is run by your cars battery. Fuel pumps
    mounted to the engine use the motion of the engine to pump the fuel

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You have leaking fuel injectors

Posted on Jan 07, 2009

  • Jerry Parmanand Jan 07, 2009

    The spark plugs in your engine can give you valuable information about how the engine is running. The chemical reaction inside the combustion camber will leave deposits on the spark plug that can tell you the condition inside the engine's combustion chambers. For example: if the engine is running rich all of the spark plugs will have a black or grey shoot covering the spark plug electrode.

  • Jerry Parmanand Jan 07, 2009

    My advice is to do a- Engine compression test it's very important for a smooth running engine. An engine depends on an equal compression reading in each cylinder to run smoothly. If poor compression exits in one or more cylinders it can cause a rough idle condition and low engine power output. A compression test of all cylinders is needed to check for engine wear and internal damage. Remove ignition coil connector or ignition system or fuel pump fuse to disable power to the ignition or fuel system to avoid fire. Compare cylinders compression reading, typical compression readings are between 125 p.s.i. and 160 p.s.i. all cylinder readings should be within about 5% of each other. If low compression exists a cylinder malfunction exits and further inspection is required. Possible causes for a low compression condition are: burned intake or exhaust valve, broken piston or piston ring, broken valve spring or a blown head gasket. your smelling blow by gases this is when you have a bad pcv valve here is how to check it




    1. Locate the PCV valve
      The PCV valve is usually located next to the valve cover of the engine, or in the intake manifold. If you cannot identify it quickly, check with the workshop manual.
    2. Check PCV valve operation
      Switch on the ignition and start the engine. With the engine idling, pinch the hose attached to the PCV valve hard enough to shut off the supply of air through it. If the valve is working correctly, the idle speed should drop enough for you to be able to hear the change. Alternatively, remove the hose from the PCV valve attached to the valve cover, leaving the valve in place, and putting your finger over the opening of the hose, you should feel suction.
    3. Clean PCV valve and hose
      Remove the hose and check that it is still pliable and not clogged with sludgy deposits. If the hose cannot be cleaned easily by blowing some air through it, then it should be replaced. Remove the PCV valve and inspect it for deposits. If it can be taken apart, then you can clean it with PCV solvent or lacquer thinners. If it cannot be dismantled but has restricted operation because of sludge, then replace it with a new one of the same type.

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  • 239 Answers

New fuel pump inside tank

Posted on Jan 07, 2009

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Did you install a new timing chain and have you checked the catalytic converter to see if its clogged? a clogged converter will make it run badly

Posted on Jan 07, 2009

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It sounds like you have the timing off at the distributor. To properly check your timing you need to set the engine to #1 cylinder top dead center. At that point, removed the distributor cap and look at where the rotor button is pointing. The rotor button should be point at the #1 cylinder (spark plug). If it is not pointing at the #1 cylinder the the distributor needs to be readjusted. It sounds like you may have the timing off by a tooth on the distributor. If the timing is set correctly, the TDC (top dead center) mark on the crank will be aligned with the mark and the rotor button will point at the #1 cylinder. If the timing is off by a tooth, it will cause the engine to over fuel (flood) and cause the condition you are having. I hope that this solves your problem and has been helpful. Please leave a good comment.

Posted on Jan 07, 2009

  • Joshua  Weaver
    Joshua Weaver Jan 07, 2009

    Did you replace the distributor cap and rotor button? If the cap is worn out, it will not fire correctly.

  • Joshua  Weaver
    Joshua Weaver Jan 07, 2009

    Never mind my last question. I just saw that you did replace the cap and rotor button.

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This may be a dumb question but explain running bad. Were the plugs black when you pulled them out, did it have a miss, what was it doing?

Posted on Jan 07, 2009

  • bob collins
    bob collins Jan 07, 2009

    I used to be a mobile mechanic. Did the engine shake or was it slow on take off or what. Did you do a compression test before and after? So far it sounds like a weak coil. This could be tested with a test light on each cylinder while it is running. If it wont flash the light, your spark is too weak. Either that or you were flooding which would produce a rotten egg smell going down the road. Wipe your finger at the end of your tail pipe and see if it turns black. If it does, Use bleach to clean the pipe and run it for a couple of days to see if it returns. I can only hope you report good or even fixya on each of my comments as each could be extensive.

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There is a solenoid that changes the exhaust cam timing. p1345 is a crank/cam sensor correlation fault possibly due to a failure in this solenoid.other possible causes include engine timing, pcm, wiring, oil sludge build-up, etc. replacing either of the cam/crank sensors will only make this issue worse as the pcm has no idea which to trust anymore for the relearn process.

Posted on Jan 07, 2009

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I would re-check the timing and make sure cam sensor is ok!

Posted on Jan 07, 2009

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Have You Checked Your Spark Plug Gap? If Its Not Firing properly It Would Cause Rough Idle And A Strong Fuel Smell From Unburned Fuel In The Exhaust.

Posted on Jan 07, 2009

  • Michael Fisher
    Michael Fisher Jan 07, 2009

    Plugs Are Almost Always Mis properly Gapped From Factory.
    Also If You Want You Can Purchase Plugs That Are One Hotter From The Auto Part Store.


  • Michael Fisher
    Michael Fisher Jan 07, 2009

    I Would Highly Recommend Some Injector Cleaner In The Fuel.
    Is There Any Tapping Sounds Under The Hood?


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Hi rdhomesoluti

are you sure the cam gears are lined up also when you line up the crankshaft? There should be markings on them too for where they go.


bestdarngood

Posted on Jan 07, 2009

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Not sure this could be the problem but have you checked the fuel pressure at different rpms, Is the fuel pressure regulator working. I am sure if you have enough knowledge to overhaul you know for certain it is in time, the chain and ignition?

Posted on Jan 07, 2009

  • David Johnson
    David Johnson Jan 07, 2009

    have you checked your injectors also?

  • David Johnson
    David Johnson Jan 07, 2009

    I think emissionwiz has correctly diagnosed your problem properly Honestly.

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Sounds like you have injector(s) problem. I would put some injector cleaner in the fuel. Also when you start it do you "pump the pedal"?

Posted on Jan 07, 2009

  • Jay Glendenning
    Jay Glendenning Jan 07, 2009

    Press and hold the gas pedal all the way against the floor while you
    crank it. That should place it in "clear flood" mode, and not inject
    any gas.

  • Jay Glendenning
    Jay Glendenning Jan 07, 2009

    Sounds like you have a wiring problem .. no change after taking wires off?!?!?

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This code is saying that their is a major difference in the signals from the crankshaft sensor and the camshaft position sensor, it does not indicate a defective sensor, what it does indicte is a possiable disconnected cam sensor or a basic timing issue. Recheck your work.
FROM THE MANUAL:
P1345 - Crankshaft Position (CKP)-Camshaft Position (CMP) Correlation

Posted on Jan 07, 2009

  • yadayada
    yadayada Jan 07, 2009

    well u haven't addressed the issue of the out of sync can to crank sensor, these will play heck with fuel control, I know you're stressed over this, buy u did something wrong when u put it bacj together, check the can and crank sensor connectors, also check and make u hooked up all the engine grounds, some I think are at the back of the heads, look carefully.

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