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  1. #1

    Default HELP!! Mercruiser 5.7 wont start

    Hello everyone, newbie to the site and hoping someone can help. So here is the long story:<br>2000 Searay 210 Signature, Mercruiser 5.7 EFI TBI, Serial number 0L640144<br>I've owned the boat about a year now, first couple months boat was running great. Then I started having "vapor lock symptoms". After getting up to operating temp and shutting down and sitting for awhile it would not start. I would have to let it cool down for a couple of hours then it would run fine again. Now, last time out ran really well, still had the no start issue after sitting. Then the next day it wouldnt start. It turns over, but will not start. After looking into it, I had no spark, no fuel at injectors when cranking, no movement on the tach when cranking and no oil pressure when cranking. When I release the key I get a single pulse of fuel from the injectors, and the oil pressure goes up for a second. I have spark from coil to distributor, but none after that.Here is everything that has been done:<br>Compression is 160-170 on seven plugs and 150 on one. New: coil, wires, plugs, cap, rotor, ignition sensor under cap, battery, starter, key ignition switch, high pressure fuel pump, fuel pressure regulator, alternator. ECM was sent out for testing and is in perfect working condition and states all sensors are working. I have disconnected the gray tach wire, no change. Neutral cut off switch looks new, tried pushing the button making sure it wasnt sticking, ( is there a way to test it)? Would the 90 amp starter fuse cause these symptoms? I've checked all grounds that I could find and all seemed ok. I'm at a loss of what to do next. Odd how it ran fine one day, the next nothing? Any help would be greatly appreciated.

  2. #2

    Default Re: HELP!! Mercruiser 5.7 wont start

    I must have a really screwed up problem, no responses? So I purchased a scan tool and noticed, with the key in the run position I have 12v at the ignition, when I turn it to the start position I get 0v at the ignition, then 12v again when I release the key. Any thoughts?

    Thanks in advance

  3. #3
    Join Date
    Jun 2008
    Location
    Island Heights, NJ,
    Posts
    3,324

    Default Re: HELP!! Mercruiser 5.7 wont start

    Bad ignition switch....
    Capt Bob
    1969 23ft ChrisCraft Lancer
    Merc 5.7L 260HP/ Volvo 280

  4. #4

    Default Re: HELP!! Mercruiser 5.7 wont start

    Thats what I would think also if it wasnt brand new.

  5. #5
    Join Date
    Jun 2008
    Location
    Island Heights, NJ,
    Posts
    3,324

    Default Re: HELP!! Mercruiser 5.7 wont start

    If there are volts on the 12V to the switch and 12V appears on the "ignition" lead when the switch is turned to IGN and it goes a way when you switch to START ... Bad (or incorrect) switch... You should see +12 on both IGN and START leads when switch is in START position.
    Capt Bob
    1969 23ft ChrisCraft Lancer
    Merc 5.7L 260HP/ Volvo 280

  6. #6

    Default Re: HELP!! Mercruiser 5.7 wont start

    Thanks sandkicker, that's what I thought. I'm going to put the old one back in and check it again.

  7. #7

    Default Re: HELP!! Mercruiser 5.7 wont start

    Quote Originally Posted by struss3 View Post
    Thanks sandkicker, that's what I thought. I'm going to put the old one back in and check it again.
    so I swapped key switches and tested both, both are good. Traced all major wires for continuity and all tested fine. If I jumper the relay solenoid I get spark from the coil and fuel at the injectors, but no spark at plugs.

  8. #8

    Default Re: HELP!! Mercruiser 5.7 wont start

    If you get spark at the coil but not plugs check the cap and rotor you must be loosing it to ground there

  9. #9

    Default Re: HELP!! Mercruiser 5.7 wont start

    Quote Originally Posted by Dieter View Post
    If you get spark at the coil but not plugs check the cap and rotor you must be loosing it to ground there
    cap, rotor and sensor under cap are all brand new, twice. What would cause spark and fuel when jumping the solenoid but nothing when turning the key?
    Thanks for your response

  10. #10

    Default Re: HELP!! Mercruiser 5.7 wont start

    Quote Originally Posted by struss3 View Post
    cap, rotor and sensor under cap are all brand new, twice. What would cause spark and fuel when jumping the solenoid but nothing when turning the key?
    Thanks for your response
    Just to clarify nothing when you turn the key?

    when you jump the relay you get spark off the coil but not off the distributor?

    what relay are you jumping the starter slave solenoid or other relay related to Efi?

    Are you getting 12 v to close the relay?

  11. #11

    Default Re: HELP!! Mercruiser 5.7 wont start

    Quote Originally Posted by Dieter View Post
    Just to clarify nothing when you turn the key?

    when you jump the relay you get spark off the coil but not off the distributor?

    what relay are you jumping the starter slave solenoid or other relay related to Efi?

    Are you getting 12 v to close the relay?

    when I turn the key it cranks but will not start. No spark from coil, no fuel from injectors, no tach movement and no oil pressure. When I release the key I get a quick spark, pulse of fuel and oil pressure goes up.

    I am jumping the slave solenoid.

    not sure about 12v to close the relay, ( not sure what your asking, not a mechanic by any means, just following what I find on here and service manual 24.)

    thanks again for all responses.

  12. #12
    Join Date
    Jun 2008
    Location
    Island Heights, NJ,
    Posts
    3,324

    Default Re: HELP!! Mercruiser 5.7 wont start

    Jumping the slave solenoid only powers the starter motor..... therefore no volts to ignition.
    Capt Bob
    1969 23ft ChrisCraft Lancer
    Merc 5.7L 260HP/ Volvo 280

  13. #13

    Default Re: HELP!! Mercruiser 5.7 wont start

    But how come when I jump the slave I get spark, fuel, etc? Turning the key it cranks but no spark, fuel etc.

  14. #14

    Default Re: HELP!! Mercruiser 5.7 wont start

    Sorry, I read elsewhere that jumping the slave bypasses the neutral safety switch, I guess thats where my problem lies?

  15. #15

    Default Re: HELP!! Mercruiser 5.7 wont start

    http://www.atlanticmobilemarine.com/...ual%205&57.pdf

    this is a pdf of the service manual. pg 4E-6 has the electrical schematic for your engine. section 5G has some diagnostic/troubleshooting charts that could be helpful to run through and narrow down the issue.

    on the wiring diagram circuit breaker (#4) powers the efi system harness (A) would check when in run you have 12 v here.

    if you have to you the slave solenoid (aka relay) you may not be getting 12 v on the yellow/red wire (#7 in cannon plug). Not sure if you checked getting 12v back from ignition switch ? You can check /isolate/ jumper around the helm by taking the cannon plug (10 pin round engine to helm harness connection) apart and check for the following:

    red/purple wire #6 - should have 12v supply constantly from battery lug on starter. if this is no go either 90 a fuse on starter is blown or 50 a breaker is tripped or bad, or you have bad battery cable connections.

    if you maintained jumper from #6 to purple #5 this should supply power to the ignition system put that jumper in place and do the following -

    momentarily jumper #6 to pin #7 Yellow/red wire it should bump the starter.

    you can test run the engine this way, just pull the maintained jumper from pin#5 to cut off the ignition when you want to shut it down. if it runs this way you have an issue with the helm/helm harness or connections to and from it.

    one other thing when you jumper the slave solenoid you get spark at the coil but not the spark plugs? if you get a spark off the coil but not off the distributor only can be a short to ground or bad connection in the cap/rotor, possible parts mismatch since you just replaced.

  16. #16

    Default Re: HELP!! Mercruiser 5.7 wont start

    Thanks Dieter, I will look into these suggestions tonight.

  17. #17

    Default Re: HELP!! Mercruiser 5.7 wont start

    New
    Well, not the slave, checked voltage through wiring. 12v all the way around through the barrel connector, only getting 7-9v at slave on small red/yellow wire. I guess it’s between there and engine side of barrel connection

  18. #18

    Default Re: HELP!! Mercruiser 5.7 wont start

    Quote Originally Posted by struss3 View Post
    New
    Well, not the slave, checked voltage through wiring. 12v all the way around through the barrel connector, only getting 7-9v at slave on small red/yellow wire. I guess itís between there and engine side of barrel connection
    New
    So I just checked again, if I disconnect the red/yellow at the slave I have 12v, when I reconnect and check I have 7v. If I run a ground from battery to either the black/yellow terminal or the black wire screwed to the red push button breaker I get 7v

  19. #19

    Default Re: HELP!! Mercruiser 5.7 wont start

    Quote Originally Posted by struss3 View Post
    New
    So I just checked again, if I disconnect the red/yellow at the slave I have 12v, when I reconnect and check I have 7v. If I run a ground from battery to either the black/yellow terminal or the black wire screwed to the red push button breaker I get 7v
    So hereís where I am. 12v to r/y wire at slave, when I turn key to start it drops to 9v. If I run a jumper from battery to the r/y terminal on the slave it fires up. So I ran a jumper from r/y terminal at the key straight to the slave, same issue.

  20. #20

    Default Re: HELP!! Mercruiser 5.7 wont start

    Quote Originally Posted by struss3 View Post
    So hereís where I am. 12v to r/y wire at slave, when I turn key to start it drops to 9v. If I run a jumper from battery to the r/y terminal on the slave it fires up. So I ran a jumper from r/y terminal at the key straight to the slave, same issue.
    12v at purple (accessories) wire at key in run position, 0v in start position. This is third new switch Iíve tried. What else would cause this?

  21. #21

    Default Re: HELP!! Mercruiser 5.7 wont start

    You’re loosing voltage in the connections or harness. If you take it straight off the battery and it works this proves it out. Did you try jumping it at the cannon plug to isolate the dash harness from engine harness? If it jumps at the cannon plug then you need to clean connections from the cannon plug to dash and back to the engine. the 12 v supply often is daisy chained in series through each gauge which is not great as it makes multiple connection points to corrode and get loose.

    it’s not hard just tedious in the end may be worth starting at the battery both positive and negative remove and clean all connections including the 12 v lug on starteR and block ground by flywheel cover. Take every one apart and make sure they are clean and shinny metal

  22. #22

    Default Re: HELP!! Mercruiser 5.7 wont start

    Quote Originally Posted by Dieter View Post
    Youíre loosing voltage in the connections or harness. If you take it straight off the battery and it works this proves it out. Did you try jumping it at the cannon plug to isolate the dash harness from engine harness? If it jumps at the cannon plug then you need to clean connections from the cannon plug to dash and back to the engine. the 12 v supply often is daisy chained in series through each gauge which is not great as it makes multiple connection points to corrode and get loose.

    itís not hard just tedious in the end may be worth starting at the battery both positive and negative remove and clean all connections including the 12 v lug on starteR and block ground by flywheel cover. Take every one apart and make sure they are clean and shinny metal
    thanks dieter, just jumped from battery to purple terminal at key, fired right up. 12v to purple after shifter but not at cannon plug( which I did the other day). I think that isolates it to the gauges?

  23. #23

    Default Re: HELP!! Mercruiser 5.7 wont start

    So If i read this correctly you don't have 12 v supplied at the switch unless you bring it direct from the battery with a jumper? Then yes somewhere under the dash you are missing the 12v supply - assuming you verified 12v supply to dash harness at cannon plug pin #6.

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