5.7 thunderbolt igitition no spark prob help

[bolo78910]

ok helping out a fellow boater help need please.

mercruiser 1986 5.7 has the thunderbolt old stile box bolt to the riser.

after taking the the engine apart to change head gaskets, hook everything back up but now we cant get any spark, before the season start he had install a new module in the distributor,. boat was starting fine before the work .

he has the boat yard mechanic check the iginition system, he said because he did not ground the black wire from the dist module it kill the module he went on to say the box on the riser is also dead, but the box was grounded, so how come both module just dead like that, kinda fishy. your thought guys.

with the key turn on we got juice on both side of the coil.

 

[achris]

Re: 5.7 thunderbolt igitition no spark prob help

 

[bolo78910]

Re: 5.7 thunderbolt igitition no spark prob help

thanks for chat even tho i dont understand it much lol will give it my best shot.

one more ?? sopose he did not put back the distributor on tdc will that cause it not to spark,

 

[Bt Doctur]

Re: 5.7 thunderbolt igitition no spark prob help

the dist dosent care , it will provide the means to make a spark, now putting it in the wrong position it wont run but will spark.

 

[bolo78910]

Re: 5.7 thunderbolt igitition no spark prob help

ok bt that solve that thought. but isnt it rare for both mudule to just quit, i told the guy to at least change the dist module first and see.

 

[bolo78910]

Re: 5.7 thunderbolt igitition no spark prob help

update,ok guys we put a new dist module in, also we got a use iginition module wire it up and she start fine, take her out for a run the boat wouldnt go over 2500 rpm timing is at 8 degree i bump up thev timing to 10 as rapido marine has said his 5.7 engine must be time at ten degree, same thing boat will not rev pass 2500 rpm.

retest the oil and no more water is getting in the engine oil.

so what now guys , the wrong moudul that bolt to the riser.

thanks for any info you got

 

[bolo78910]

Re: 5.7 thunderbolt igitition no spark prob help

up date for all who intrested never like to end a thread without letting everyone knows what was the fix, now went back to the boat did some more tricks still not getting over 2500 rpm on the water. take it back to the dock raise the drive to take a look at the prop, bingo that ss prop looks like when you would mix sement and dip the prop in take it out and let it dried. what would cause that it wasnt realy barnacel alone, the drive is also eaten up . the boat was put in the water in april all the zincs is almost eaten off.

any to make a long story short haul the boat and clean drive/prop install new sinks power wash the bottom , boat is now running like a dream /fix

now what would cause this boat having the zincs eaten away so fast, any cure for this??? thanks to everyone who respond to this thread.

 

[RichM]

Re: 5.7 thunderbolt igitition no spark prob help

Sounds like you or a boat in a slip around you has an electrical problem. I am not completely sure about what causes it myself, but it has something to do with a bad ground (I think?), so it grounds into the water and eats all of the zincs in the area. That is my rough understanding of it, and if someone else wants to chime in with a better explanation, please fee free.