165 hp mercruiser 1970 losing spark?

[70Silverline]

i have a 1970 inline 6 cylinder mercruiser/gm it has great spark within the first 2-3 seconds of starting and while still cranking or after it fires it dies no spark whatsoever does anyone have a clue im lost!!

 

[70Silverline]

Re: 165 hp mercruiser 1970 losing spark?

just to clear something up it has fire when cranking and sometimes tries to start but fire dies out after 2-3 seconds no matter what happens?

 

[70Silverline]

Re: 165 hp mercruiser 1970 losing spark?

guess no one knows huh?

 

[CheapboatKev]

Re: 165 hp mercruiser 1970 losing spark?

patience amigo....

You want any answer or the right answer?

when was the last time she had a complete tune up?
Points plugs, timing checked?

All your wiring clean & tight? wire brushed shiny clean and a little grease after tighting them up?


much better minds than mind will stop in and help...seems you really needed a reply..lol

 

[ziggy]

Re: 165 hp mercruiser 1970 losing spark?

well, here's a couple of thoughts, pretty much out of the book though...

for a no spark, weak-red or yellow spark. some possiblilites are...

poor connections or damaged ign. wiring
shorted tach (for a tach that's wired in series with the coil)
ign. points improperly gaped, burned or dirty
faulty ign. switch
faulty condenser
faulty coil
faulty ballast or resistance wire
improper ign. timing

i'll be looking into a few of these things myself as my rig died at the lake and wouldn't restart. after wiggleing some wires, it started and ran.

i'll second do the tune up thing.

 

[windsors03cobra]

Re: 165 hp mercruiser 1970 losing spark?

So just to clarify, it has spark while cranking and starts but when you let the key go into the run position it dies ?

Sounds like some troubleshooting with a volt ohm meter is in order or a test light in a pinch/low tech solution.

 

[Bt Doctur]

Re: 165 hp mercruiser 1970 losing spark?

From the description of wanting to start when key is in "start" and dies when key is in "run" you missing the power to the coil in the "run "position.
Bad ign fuse, key switch, loose wire,bad ballast resistor or resistor wire, corroded main harness plug. Try hot wiring 12V directly to the + side of the coil and turning the key. If it runs the trouble is no power to the coil in the "run " position. Fix the problem because the coil IS NOT designed to run 12V

 

[70Silverline]

Re: 165 hp mercruiser 1970 losing spark?

first sorry for bieng short with everyone and wanting an answer was wrong of me i apoligize but im so frustrated just spent 500 at the boat shop less than 2 weeks ago and another problem is here allready lol its ok thats why the new name is money pit lol anyways i think the keyed ignition maybe the problem the key spun clear around like 2 times before hooking and actually working last week after it had its problems cant bielive i didnt think of that maybe if i change that (and since i burnt up my point by improper wire placement)replace my points condensor rotor button YET AGAIN for the second time in 2 weeks maybe she will fire fine i will do all of this tommorow and get back so we can all know exactly what it was.......

as for the fire when i turn the key to start the motor (keys working fine now but spun around 2 times before hooking up 2 weeks ago)it will have fire NOT just when it start it doesnt matter when im turning or when it starts whatever happens wether it starts or not it loses fire after 2-3 seconds