1973 mercruiser 120 HP no spark

[rloucks3]

I burned up the points, I will get some today and re check reading

 

[rloucks3]

I burned up the points, I will get some today and re check read

 

[Scott Danforth]

there should be enough contact material left to file and set to verify.

 

[alldodge]

The Tan and brown are probably from the trim limit and gauge

 

[rloucks3]

Okay I cleaned everything up, getting 12 volts key in on position. Getting 10.5 @ in start position. I do have a spark at the points. Good sign?? I surely hope so.

 

[rloucks3]

So I bought this boat as a project. Mistake??? The trim motor didn't work, there is 2 wires coming out of the stern where the outdrive connects to the motor. The wires were bare. So I abandoned the old trim and put in the up and down solenoids.

 

[rloucks3]

So I guess my next step is to get new points and see what happens???

 

[alldodge]

You could but you said your seeing spark at the points. Seeing spark there means you should see spark at the coil. Take coil wire and put it close to the block to see if it will spark. Of place a spark plug on a plug wire and ground case to block

 

[rloucks3]

There's a spark a little faint.

 

[Scott Danforth]

There's a spark a little faint.

Did you adjust the dwell to 30 degrees? Yes or No

 

[alldodge]

There's a spark a little faint.

Might have burned the coil out from all the smoke earlier

I don't normally say this, but since coils are so cheap and we're having issues, might pick one up and change out.

The issue is up thru 1973 the coil did not use a external resistor. Your wiring shows there is no start and run wiring, only run wiring. This means the coil gets full 12V starting or running.

In 1974 motors started using start and run wires. This made the points last longer. So I would suggest getting a external resistor coil and ballast resistor. If it runs shut it down, then install ballast resistor on the run circuit to the coil. Then add a new wire from starter solenoid to the + side of coil

On the other side might go back to full electronic ignition and dump the points. Would suggest Delco EST

But your call

 

[rloucks3]

Did you adjust the dwell to 30 degrees? Yes or No

Yes as close as I could no dwell meter, I replaced the r wire and still getting the same 12 volts key on 10 key in start position.

 

[Scott Danforth]

Suggest you borrow a dwell meter.

 

[rloucks3]

I ordered one.

 

[rloucks3]

Suggest you borrow a dwell meter.

Right now I am waiting for parts and resister.

 

[rloucks3]

I have a 1973 mercruiser with a 120 mercruiser. I put a volt meter on ohms and the red probe where the plug wire goes with key on I get 9.49 ohms, I try to start and I get the same. I have a flame thrower petronics and petronics electronic ignition.

 

[nola mike]

I have a 1973 mercruiser with a 120 mercruiser. I put a volt meter on ohms and the red probe where the plug wire goes with key on I get 9.49 ohms, I try to start and I get the same. I have a flame thrower petronics and petronics electronic ignition.

Did you install that resistor wire?

 

[Scott Danforth]

I have a 1973 mercruiser with a 120 mercruiser. I put a volt meter on ohms and the red probe where the plug wire goes with key on I get 9.49 ohms, I try to start and I get the same. I have a flame thrower petronics and petronics electronic ignition.

When did you add the pertronix? And has it ever run?