Please help!!! Mercruiser 5.7 Not starting Please help!!!

Alex57

Cadet
Joined
May 18, 2006
Messages
19
Hello everyone, <br /><br />I am a begginer with boats but have some experiance with cars... <br /><br /><br />Just bought a '96 bayliner ciera with a Mercruiser 5.7 litter 2 barrel <br />carb Thunderbolt 5 Ignition <br />The thing ran fine for a while, then wouldnt start when hot and <br />eventually now doesnt start at all. <br /><br /><br />It cranks, turns over but no signs of life. I am getting gas for sure, <br />can see it in the carb. <br />I already changed the spark plugs, wires, cap, rotor. No change. <br />There is voltage going to the coil and continuity throught the coil. <br /><br /><br />There is spark comming from the main ignition wire (visible if you <br />touch ground) <br />There is also spark comming off the ignition wires (when you touch <br />ground) <br /><br /><br />When it did run, it ran just fine and I didnt't touch anything, so I <br />doubt it's the timing.. <br /><br /><br />SO I get gas, I get spark and nothing.... I am aware of the ignition <br />module/sensor and some kind of a changable ignition pick up sensor in <br />the distributor, but I have no idea how they work and wether they are <br />the problem. Me and my buddies are totally stuck. Anyone have any <br />ideas? <br /><br /><br />Any help would be greatly appreciate it.... <br /><br /><br />Thank you, <br /><br /><br />Alex.
 

QC

Supreme Mariner
Joined
Mar 22, 2005
Messages
22,783
Re: Please help!!! Mercruiser 5.7 Not starting Please help!!!

You sure you don't have a fuel filter full of water?
 

Alex57

Cadet
Joined
May 18, 2006
Messages
19
Re: Please help!!! Mercruiser 5.7 Not starting Please help!!!

Thanks for your reply QC<br /><br />Filter? hmmm<br /><br />I did try starting with starter fluid and that didnt help...<br /><br />I didn't check that... Could that be it?<br /><br />which one of the two filters?<br />Is it hard to replace?
 

DayCruiser

Ensign
Joined
Sep 24, 2004
Messages
953
Re: Please help!!! Mercruiser 5.7 Not starting Please help!!!

YOu should have a fuel filter between the gas tank and the fuel pump. Looks like a oil filter. If not then you may have water in the fuel pump and/or the carb
 

Don S

Honorary Moderator Emeritus
Joined
Aug 31, 2004
Messages
62,321
Re: Please help!!! Mercruiser 5.7 Not starting Please help!!!

There is spark comming from the main ignition wire (visible if you <br />touch ground) <br />There is also spark comming off the ignition wires (when you touch <br />ground) <br />
I'm not really sure rather you are checking the primary wiring or secondary, so try this.<br />Pull the center wire out of the distributor cap.<br />You will need to stick a screw driver in the end of the wire in contact with the metal clip. Then hold the shank of the screw driver about 1/2" from a good ground and crank the engine. You should get a bright blue spark that easily jumps that 1/2" gap. Touching the ground tells you nothing.
 

boathog

Seaman Apprentice
Joined
May 11, 2006
Messages
39
Re: Please help!!! Mercruiser 5.7 Not starting Please help!!!

sounds like carb is flooding . may need float adjustment or carb cleaned out . try starting it at full throtle (keep your hand on the throtle) dont pump the gas.
 

marinemech1

Chief Petty Officer
Joined
Mar 26, 2005
Messages
623
Re: Please help!!! Mercruiser 5.7 Not starting Please help!!!

be careful if boathog is correct<br />check oil for signs of fuel if fuel is in oil due to engine flooding don't try to start change oil
 

Alex57

Cadet
Joined
May 18, 2006
Messages
19
Re: Please help!!! Mercruiser 5.7 Not starting Please help!!!

Thanks everyone for your replies.<br /><br />I bought a spark testing tool and performed a test out of the mercruiser book.<br /><br />it said to plug the spark tool into ignition coil wire then unplug the distributor module and crank. According to the test, it's a failed ignition pick up sensor in distributor underneath the rotor. I will try to replace it and see if that helps.. <br /><br />THe oil is clean and full throttle start does not help. I will change the the sensor and let you guys know.<br /><br />THanks again.<br /><br />Alex.
 

michael-lagrange

Petty Officer 1st Class
Joined
May 3, 2006
Messages
211
Re: Please help!!! Mercruiser 5.7 Not starting Please help!!!

--------------------------------<br />then wouldnt start when hot and <br />eventually now doesnt start at all. <br />--------------------------------- <br />Ignition problem.
 

I/O WALDO

Petty Officer 1st Class
Joined
Nov 16, 2005
Messages
320
Re: Please help!!! Mercruiser 5.7 Not starting Please help!!!

Hang parts till it runs?
 

Don S

Honorary Moderator Emeritus
Joined
Aug 31, 2004
Messages
62,321
Re: Please help!!! Mercruiser 5.7 Not starting Please help!!!

I bought a spark testing tool and performed a test out of the mercruiser book.<br /><br />it said to plug the spark tool into ignition coil wire then unplug the distributor module and crank.
If you unplug the ignition module, of course you won't have spark. But that doesn't tell you anything about the sensor in the distributor. <br />Here is the troubleshooting chart. For the TB5 ignition. Follow it and do a retest before you replace that sensor.<br />What kind of "Mercruiser Book" are you going by?<br /><br />
TB5%20Troubleshooting%20chart.png
 

Alex57

Cadet
Joined
May 18, 2006
Messages
19
Re: Please help!!! Mercruiser 5.7 Not starting Please help!!!

Don, that is exactly the chart I am using so it must be the same book.<br /><br />Where it says Reconect WHT/RED .... in thge biggest box in the middle. I did that. ANd there is spark. So if I am reading this correctly, that means I gotta replace the distributor pick up/sensor. I took it appart and will get a new one today. Hope that helps and the problem is not the carb flooding or something else...<br /><br />THe thing that bothers me about this test, is that although it makes sense... it's for a no spark condition. I think my spark is weak, but I do have at least some spark all the way down to the cilynders
 

Alex57

Cadet
Joined
May 18, 2006
Messages
19
Re: Please help!!! Mercruiser 5.7 Not starting Please help!!!

Hey Guys, <br /><br />changed the sensor... no change. Got spark, but then again I had spark before. :( <br /><br />After cranking it for a bit, I looked into the carb and maaaaan there is alot of gas in there..<br /><br />COuld it be the carb? flooding the motor? <br /><br />Funny thing, it's still dripping long after i stop cranking..<br /><br />THis has been a frustrating 2 weeks and no progress what so ever... :( <br /><br />Well looks like i will need a pro after all, but i will let you guys know what it was after I figure it our so this nonesense does not happen to you. :)
 

I/O WALDO

Petty Officer 1st Class
Joined
Nov 16, 2005
Messages
320
Re: Please help!!! Mercruiser 5.7 Not starting Please help!!!

Lucky you didnt burn yerself up!! Carb Floodin! Get someone who knows SOMETHING about diagnostics to look at it b-four you hurt someone!(opinion)
 

Alex57

Cadet
Joined
May 18, 2006
Messages
19
Re: Please help!!! Mercruiser 5.7 Not starting Please help!!!

Thanks Waldo :) <br /><br />I mean flooding inside the manifold, not anywhere else.. proly needs a rebuild.
 

Alex57

Cadet
Joined
May 18, 2006
Messages
19
Re: Please help!!! Mercruiser 5.7 Not starting Please help!!!

Turned out to be a tight/jammed choke that didnt operate properly. The mechanic at the marina tuned the carb, fixed the choke and had me ready to go in about 5 minutes....<br /><br />Moral of the story when in doubt, check the choke operation thouroughly.<br /><br />thanks aeveryone for your replies.
 
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