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  1. #1
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    Question Cant get mercruiser 4.3 in time!!!!!!!

    I have a 1995 maxum with a mercruiser 4.3 vortec webber 4 barrel carb thunderbolt IV ignition system. Recently I had an issue with it not starting. So I replaced the dist cap rotor wires plugs rebuilt the carb new fuel pump and fuel lines, I checked the tank vent and check valve. im getting plenty of fuel. I got it running after finding out My oil pressure switch was bad. Now I can not get the motor to run on 8 deg before tdc. It will run at about 25 deg btdc but nothing close to what it is supposed to be. under load at this timing obviously the motor runs like crap hesitating stalling and just running like crap. What could be causing this??? I am at wits end trying to figure out what is going on. I have verified that the plug wires are in the right order. Please help.

  2. #2
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    Default Re: Cant get mercruiser 4.3 in time!!!!!!!

    are you checking timing on #1 cylinder??

    did you remove the distributor at all??

    do you need to put the ignition into service mode to check/set timing and idle??

  3. #3
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    Default Re: Cant get mercruiser 4.3 in time!!!!!!!

    I have verified that when tdc the rotor is pointing to number one. I have not removed the dist. and on thunderbolt IV there is no timing mode like thunderbolt V has.

  4. #4
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    Default Re: Cant get mercruiser 4.3 in time!!!!!!!

    the rotor is pointing to number one.
    does that mean pointing to #1 cylinder or #1 on the cap?
    http://www.boatfix.com/merc/Servmanl/18/18B4R2.PDF

  5. #5
    Lieutenant Commander Alpheus's Avatar
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    Default Re: Cant get mercruiser 4.3 in time!!!!!!!

    Make sure you are on cylinder #1

    Here is the manual you need.

    http://www.4shared.com/document/IqpH...anual_7_GM.htm


    1969 StarCraft Chieftain, 4.3 Mercruiser Alpha One Gen II

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    Its What I Don't Say You Should Be Worried About...

  6. #6
    Ensign EddiePetty's Avatar
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    Default Re: Cant get mercruiser 4.3 in time!!!!!!!

    ...check your dampner, it may have slipped on its mount (draw a chalk line across face and run the engine to detect movement).
    Eddie Petty. #3 Dirt Modified
    Courtland, Virginia
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  7. #7
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    Default Re: Cant get mercruiser 4.3 in time!!!!!!!

    Pointing to where number one is on the dist cap and number one cylinder is at tdc, no matter wich way i rotate the dist cap it will not run properly. all the way one way it wont even start it will only start if it is rotated all the way counter clockwise that it allows me to turn it. This might be far fetched but could this be the issue......

    i have heard that the higher the compression the hotter spark is needed if the engine will run at 25 deg before tdc (piston hasnt compressed the air fuel mixture completly) but wont run at 8 deg btdc full compression. in theory if it was a week coil sending a week spark it might not be enough spark to ignite the air fuel mixture at full compression......

  8. #8
    Ensign EddiePetty's Avatar
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    Default Re: Cant get mercruiser 4.3 in time!!!!!!!

    Quote Originally Posted by ussoldier_1984 View Post
    ......Pointing to where number one is on the dist cap and number one cylinder is at tdc, ......

    ......#1 @ tdc: Now is that on the compression stroke or exhaust stroke?
    Eddie Petty. #3 Dirt Modified
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    V-20 Wellcraft
    3.7 470 Mercruiser

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    25 Yamaha, 25 Johnson, 25 Evinrude, 9.9 Evinrude, 4 Johnson, 2.5 Johnson

  9. #9
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    Default Re: Cant get mercruiser 4.3 in time!!!!!!!

    compression stroke, and I have never pulled the dist out. it was running great last month prior to me having an issue with my oil pressure switch.

  10. #10
    Ensign EddiePetty's Avatar
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    Default Re: Cant get mercruiser 4.3 in time!!!!!!!

    ...try post #6 !!!
    Eddie Petty. #3 Dirt Modified
    Courtland, Virginia
    V-20 Wellcraft
    3.7 470 Mercruiser

    Stumpnocker
    25 Yamaha, 25 Johnson, 25 Evinrude, 9.9 Evinrude, 4 Johnson, 2.5 Johnson

  11. #11
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    Default Re: Cant get mercruiser 4.3 in time!!!!!!!

    When you recently had an issue with it not starting, would it just up and not start? period? So then you replaced the cap, rotor, wires, plugs, replaced all the fuel lines, fuel pump and rebuilt the carb just because? Does it have a fuel water separator? Was it replaced? Then it still wouldnt start till you replaced the oil pressure sensor but it was out of time so THEN you set it to 8degrees? What was it set on before?

    You need to make 100% sure that you have those wires on correctly. Nothing wrong with the timing light? How did you verify piston 1 is TDC with the rotor pointing to wire #1?
    1990 Stardust
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  12. #12
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    Default Re: Cant get mercruiser 4.3 in time!!!!!!!

    Thanks didnt see that I will deffinitly check that tomorrow..... But the engine will not run good at all when the dist is in the small window of adjustment that i can turn the dist which tells me that chances are it didnt move on me. i was out on the lake today to try to tune it by feeling how the engine runs then i was gonna fine tune with my timing light. no matter where the dist was it would not run properly it would stall and hesitate and no power at all.

  13. #13
    Commander bifflefan's Avatar
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    Default Re: Cant get mercruiser 4.3 in time!!!!!!!

    Use a vacuum gauge to time it.

    Hook it to a manifold vacuum port then start the engine, at idle set the timing to reach the highest vacuum you can, then retard the timing until you go back down one inch of vacuum. So if your highest is 18 then set it at 17.
    This will get you close as you can be.
    As long as the advance curve in the dist is correct, you done.

    You can recheck it with the light just to see where the marks are if you like. But only use one of the methods to set it.
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  14. #14
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    Default Re: Cant get mercruiser 4.3 in time!!!!!!!

    i did everything because I just got the boat and wanted to make sure everything was up to par. but i knew I had an ignition issue. The boat was originally good and ran at 8 degrees I losened the dist cap when i was checking the time in case i needed to adjust but it was perfect at 8 deg. I lost my balance and accedently rotated the dist a bit throwing it out of time.

  15. #15
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    Default Re: Cant get mercruiser 4.3 in time!!!!!!!

    Quote Originally Posted by ussoldier_1984 View Post
    Pointing to where number one is on the dist cap and number one cylinder is at tdc, no matter wich way i rotate the dist cap it will not run properly. all the way one way it wont even start it will only start if it is rotated all the way counter clockwise that it allows me to turn it. This might be far fetched but could this be the issue......

    i have heard that the higher the compression the hotter spark is needed if the engine will run at 25 deg before tdc (piston hasnt compressed the air fuel mixture completly) but wont run at 8 deg btdc full compression. in theory if it was a week coil sending a week spark it might not be enough spark to ignite the air fuel mixture at full compression......
    When you say it won't allow you to rotate it any further; is it hitting something physically. Do you need to pull the distributor and rotate one tooth to get the adjustment needed?

  16. #16
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    Default Re: Cant get mercruiser 4.3 in time!!!!!!!

    I dont have a vacume guage

  17. #17
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    Default Re: Cant get mercruiser 4.3 in time!!!!!!!

    Quote Originally Posted by coheej View Post
    When you say it won't allow you to rotate it any further; is it hitting something physically. Do you need to pull the distributor and rotate one tooth to get the adjustment needed?

    I can rotate it from about after tdc 5 deg to about 30 deg before tdc. I cant even pull my dist out unless I cut a hole in the figerglass that covers part of my motor. I have done all adjustments on the dist with a timing light. dist has never been taken off the tooth. it ran great at 8 deg btdc prior to my stalling out on the water when i realized I had a ignition issue which led me to do a full tune up. I can adjust the timing to 8 deg. btdc but it will not start up. it will only run if it is at about 25 deg btdc and it runs like crap. I am going to check to see if the damper has spun or moved like in post #6 but i dont think it has though

  18. #18
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    Default Re: Cant get mercruiser 4.3 in time!!!!!!!

    the engine should run and the timing should be close to the tdc mark when it is running - i would say the most advanced the engine would run at idle is about 12 deg - roughly 4 deg after

    you are either doing something wrong or you got a plug wire on wrong

    firing order is 1-6-5-4-3-2

    the cylinders are numbered on the intake manifold, large one inch numbers cast into it

    #1 is the most forward on the port side

  19. #19
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    Default Re: Cant get mercruiser 4.3 in time!!!!!!!

    Quote Originally Posted by dubs283 View Post
    the engine should run and the timing should be close to the tdc mark when it is running - i would say the most advanced the engine would run at idle is about 12 deg - roughly 4 deg after

    you are either doing something wrong or you got a plug wire on wrong

    firing order is 1-6-5-4-3-2

    the cylinders are numbered on the intake manifold, large one inch numbers cast into it

    #1 is the most forward on the port side
    I am taking a guess on how far out the timing is. as i only have a v notch to time it by and there is a mark on the crank pully to show where 8 deg is but when my timing light hits its under the water pump so i cant really tell how far off it is I have checked and rechecked the spark plug wires and firing order many many times. thats why i was asking about a week coil before could a week coil not be hot enough to allow the engine to fire at full compression? When i have the timing set to 8 deg btdc it will not start but it will if I back it off more

  20. #20
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    Default Re: Cant get mercruiser 4.3 in time!!!!!!!

    I am trying to explain the best i can. I have a tramatic brain injury so somtimes my thoughts come out all scrambled so sorry if you have trouble understanding me lol

  21. #21
    Lieutenant Commander Alpheus's Avatar
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    Default Re: Cant get mercruiser 4.3 in time!!!!!!!

    Do you need to pull the distributor and rotate one tooth to get the adjustment needed?
    That will do absolutely nothing. ^^^


    Read the manual and do the procedure for installing your distributer with engine disturbed method. Maybe the previous owner messed it up. Just start from scratch and then you will know its right..


    1969 StarCraft Chieftain, 4.3 Mercruiser Alpha One Gen II

    Link To Restoration Page


    ----------------------------------------------------

    Its What I Don't Say You Should Be Worried About...

  22. #22
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    Default Re: Cant get mercruiser 4.3 in time!!!!!!!

    Quote Originally Posted by Alpheus View Post
    That will do absolutely nothing. ^^^


    Read the manual and do the procedure for installing your distributer with engine disturbed method. Maybe the previous owner messed it up. Just start from scratch and then you will know its right..
    I have verified that the dist is where it needs to be mechanical timing is good. what about the optic sensor in the dist what if that is bad? or a week coil??? I can set the timing to the 8 deg like it is supposed to be but the engine will not start. if i back it off more it will run but run like garbage



    i have heard that the higher the compression the hotter spark is needed if the engine will run at 14 deg before tdc (piston hasnt compressed the air fuel mixture completly) but wont run at 8 deg btdc full compression. in theory if it was a week coil sending a week spark it might not be enough spark to ignite the air fuel mixture at full compression...... could it be the coil week?

  23. #23
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    Default Re: Cant get mercruiser 4.3 in time!!!!!!!

    if the ignition sensor is bad there would be no spark, 99% of the time they either work or they don't

    it could be a weak coil causing weak spark, try testing spark with a spark tester from the coil tower to a good ground

    based on your posts, there is no timing grid?? just a notch and groove in the balancer??

    if so, you will need an advance timing light to properly set timing, don't rely on someone's mark on the balancer

  24. #24
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    Default Re: Cant get mercruiser 4.3 in time!!!!!!!

    Quote Originally Posted by dubs283 View Post
    if the ignition sensor is bad there would be no spark, 99% of the time they either work or they don't

    it could be a weak coil causing weak spark, try testing spark with a spark tester from the coil tower to a good ground

    based on your posts, there is no timing grid?? just a notch and groove in the balancer??

    if so, you will need an advance timing light to properly set timing, don't rely on someone's mark on the balancer
    Yes just a v notch and the 0 degree mark from the factory and someone else made a grove where 8 deg would be but the engine will not run anywhere near the 0 deg mark or the 8 deg mark they made the only way I can get it to start if its about 6 inches to the left of the 0 deg mark and it runs like crap

    tomorrow I am going to exchange my coil its under warrenty still as for timing the engine I only have a standard snap on timing light

  25. #25
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    Default Re: Cant get mercruiser 4.3 in time!!!!!!!

    so when the light flashes, it shows the groove approx 6" to the left of the notch??

    something isn't right - at the most on #1 the groove should only be an inch or so from the notch to run - no way would the engine run, poorly or otherwise, with the groove 6 inches from the notch on #1 (that would be like 90 degrees advanced)

    do you have the manual??

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