5.7 no spark

[Mike921056]

I have a 1990 5.7 mercruiser and cant get spark. I put a new coil and a sensor in the distributer the old sensor had two wires on it and the new one came with three one green/white and one red/white and a black the old one didnt have the black so i grounded the black to the block. There is a green/white wire coming from engine harness that was spliced into the old sensors green/white wire should i splice it in the new sensor or is it supposed to be hooked somewhere else? I also disconnected the shift interuptor to elimante that ad my problem. I have 12a volts on the positive side of the coil and nothing on the negative when key is on or turning over. There is 12a volts at the red/white wire on the distributor. I am pretty much lost at this point i cant seem to get any spark. Only thing left i can think of is the thunderbolt 4 module on the riser but its kinda expensive any ideas what i should do or try?

 

[Don S]

Re: 5.7 no spark

 

[Mike921056]

Re: 5.7 no spark

What about the black wire i asked about in my original post and the geen/white one that used to be spliced?

 

[Don S]

Re: 5.7 no spark

What about the black wire i asked about in my original post and the geen/white one that used to be spliced?

Hard to say, post some pics, could be nothing more than a hack job by a previous owner or wannabe mechanic.

 

[Mike921056]

Re: 5.7 no spark

Ok i will try when it stops raining the black wire came on the new sensor in the distributor.and the green and white wire comes from the wiring harness and they used a scotch lock and tied it into the green and white wire in the sensor in the distributor as of now i havent hooked that back up cause it didnt look right but i really have no clue at this point there is also three purple wires on the positive of the coil and two gray on the negative of the coil i am not sure thats right i thought there was only supposed to be two on the positive side. I also hooked a test light on the positive of the battery and touched the negative of the coil i get light with key off but with key on or cranking i get nothing

 

[Don S]

Re: 5.7 no spark

and they used a scotch lock and tied it into the green and white wire

SUPER hack job.

 

[achris]

Re: 5.7 no spark

Here's what the wiring should look like....

 

[Mike921056]

Re: 5.7 no spark

Ok i unplugged the green / white wire on distributor and rapidly tapped it on a ground i Got spark out of the coil. I already installed a new coil and sensor in the distributor.. no spark with all hooked up using the key switch any thoughts now? Thunderbolt 4 module bad? I dont know.

 

[Don S]

Re: 5.7 no spark

Did you disconnect the shift interrupt switch and the tach as mentioned in the upper right of the troubleshooting chart?

 

[Mike921056]

Re: 5.7 no spark

E

Yeah i did

 

[Mike921056]

Re: 5.7 no spark

Did you disconnect the shift interrupt switch and the tach as mentioned in the upper right of the troubleshooting chart?

Yes i did

 

[Don S]

Re: 5.7 no spark

If you followed all of the steps, then you have a bad sensor, new or not.