77' mercruiser 165 no spark, running out of options

[semo549]

I have a 77 srv 187 searay with a mercruiser 165 in it. It was running good like it always does for 10 minutes then. died. It turns over fine, theres non spark though.

Heres what I have brand new this season in the electrical system.
coil, points, cap, wires, plugs, rotor, condensor.

I've done a few tests with my multimeter here they are:

-checked ingition switch red wire with key on, got 12 volts

-connected volt meter to positive side of coil, neg lead to engine ground. I get 4 volts.

-Points are opening fine

-tachometer is working fine (did a continuity test)

The manual is telling me to check the shift interlock switch, can anyone direct me on how to perform this test?
Is there anyone with any experience on where to go from here I'm pretty stumped.

Thanks for the help, Jim

 

[Bt Doctur]

Re: 77' mercruiser 165 no spark, running out of options

Remove all the wires from the neg side of the coil EXCEPT the one that goes to the dist. run a jumper from the + battery to the + side of the coil .
report results.

 

[semo549]

Re: 77' mercruiser 165 no spark, running out of options

Just tried what you said. Still no spark, even with the new coil. So I tried putting the old coil back in and try your test, same results; no spark, however the coil got really hot.

I don't know if this will help but I check the voltage on the positive wire that connects to the coil (wire was unconnected from the coil) and we got 12volts.

Then we put all the wires back to the coil, there is two tan wires on the positive side of the coil. one of the tan wires was getting extremely hot.

Any other suggestions?

-Jim-

 

[semo549]

Re: 77' mercruiser 165 no spark, running out of options

Does no one else have any imput?

 

[Showtime22]

Re: 77' mercruiser 165 no spark, running out of options

Push the points open and examine the contact area.
I know they are not old but could still be burned up a bit.

A light clean up with sand paper or a file may help, but may effect the setting.

IH8 PTS

 

[vxtech]

Re: 77' mercruiser 165 no spark, running out of options

i would check base plate that points are mounted too,make sure base plate is isolated from distributor body (little rubber gromments for screws) cause this WILL prevent spark

 

[searay3]

Re: 77' mercruiser 165 no spark, running out of options

only one side of the points is grounded. the side coming from the coil should not show a connection to ground unless the points are closed. Check out bubbas link, then with the points open, put a meter to them. If they are always grounded there is an issue with the points or the condensor..

 

[bruceb58]

Re: 77' mercruiser 165 no spark, running out of options

Measure the voltage at the negative side of the coil with the points open and then closed. With the points open, it should measure 12V, with closed should measure 0V.

 

[bigskiohio]

Re: 77' mercruiser 165 no spark, running out of options

i thought the tan ones were on the neg side but i will go out and check.

 

[bruceb58]

Re: 77' mercruiser 165 no spark, running out of options

i thought the tan ones were on the neg side but i will go out and check.

If it is the one that goes to the tach, it should be.

 

[Bt Doctur]

Re: 77' mercruiser 165 no spark, running out of options

From that test the trouble seems to be with the points assembly .just because you see them opening and closing does not mean their working.They can be grounded out or the condensor can be shorted out.Disconnect wire to dist, Meter on "ohms" red to dist wire, black to engine block. With points open(matchbook works) you should see infinity(no meter movement) closed should see "O" ohms(meter swings to the right)
Any change from the above report back.

 

[semo549]

Re: 77' mercruiser 165 no spark, running out of options

I caught up doing some stuff today, but I think I've narrowed the problem down closer. I'm assuming there is a bad ground on the neg side of the coil somewhere. I'll be working on it wednesday, I'll report back to you guys.

Thanks for the help so far, it's been very useful.

-Jim-

 

[parrisw]

Re: 77' mercruiser 165 no spark, running out of options

The neg side of the coil shouldn't be grounded. It should only have a momentary ground when the points close!!!! Get a 12V test light put it on the neg side of the coil, turn key on, does it light??? Now get a small screwdriver or your finger and manually open and close the points with the test light on the neg still, it should blink on and off, if not your have a problem in your points. Just replace them, cleaning is a waste of time, unless your just in a bind and need to get going, make sure to replace the condensor as well, if its bad your new points will burn out real fast.