86 mercruiser 170 ignition problem

[Cynicaltrip]

Hi guys I have a 86 mercruiser 170..put electronic ignition in it..rebuilt motor completely set timing to 6 btdc...have 3 ohm coil new...replaced purple resistor wire from choke to coil with a non resisted wire...have power to choke..coil..and everything else that needs 12v when key is on....motor will crank and crank nothing...checked for spark when cranking and it doesn't have any spark until you let go of key then it will throw 1 spark at end of cranking....about to commit a violent act I'm so fed up lol....figured id toss this problem out there and let the minds better then mine have a go at it!...the only thing I could possibly think of at this point is shift interrupter switch bad maybe? Thx again for any help....

 

[Don S]

Re: 86 mercruiser 170 ignition problem

Do you have the purple yellow wire that goes from the starter slave solenoids I terminal to the coils + terminal hooked up?

 

[stonyloam]

Re: 86 mercruiser 170 ignition problem

You may have a bad contact in the slave solenoid. In your 470 the coil gets its voltage from the small terminal on the slave (purple/yellow wire) while the starter is cranking. You do have the purple/yellow wire attached right?. Try this: run a wire directly to the coil plus from the battery + and give it a try. Also if you have a voltmeter, see if there is any voltage on the coil + while cranking. Let us know how you make out.

Don was a little quicker but at least I feel a little more confident about my answer now LOL.

 

[Cynicaltrip]

Re: 86 mercruiser 170 ignition problem

Yes I have the purple/yellow hooked up from slave..its also new...I will have to check voltage while cranking tomorrow and get back to you guys thanks for the responses so far...

 

[Cynicaltrip]

Re: 86 mercruiser 170 ignition problem

ok update....with key on i have 11.2v at coil + side....... 9.8v coil+ while cranking....after i got those readings i ran a wire from battery + side to coil+ side had 12.8v at coil+......cranked it and cranked it still nothing....shifter is in nuetral...i tried all sorts of different positions same result...can a bad shift interupter switch cause my issue and how can i test to see if that is the problem....or will that not cause wwhat im dealing with?...thanks again for the info guys much appreciated...

 

[Don S]

Re: 86 mercruiser 170 ignition problem

can a bad shift interupter switch cause my issue and how can i test to see if that is the problem...

It shouldn't have anything to do with it. But disconnect it and see if you get spark.

 

[Don S]

Re: 86 mercruiser 170 ignition problem

..put electronic ignition in it.

Has it ever had spark since it was installed? Is all of it there. Had one guy here found his kit didn't have all the parts. Check your kit to the instructions and packing list.

 

[Cynicaltrip]

Re: 86 mercruiser 170 ignition problem

yea i bought a pertronix kit but the magnet wouldnt fit called them they said they didnt make a kit for my prestolite dizzy..so then i ordered HOT SPARK kit came with everything module, magnets the works...when i purchased the boat the motor was seized...so i took it and had a machine shop work the block and then i put all new into it from there...so i personally havent ever seen it fire up lol..so thats why im questioning parts that are not new on this motor...i reused the dizzy for the electronic ignition along with the cap and other then shift interupter everything else is new....how should i go about disconnecting the shift interupter?....do i need to join the white/green stripe wires together? and the black to black?...and just remove the unit itself..? sorry if im asking rookie ?'s lol thx again for any info!!

 

[Eric 3.7LX Alpha 1]

Re: 86 mercruiser 170 ignition problem

Not a good sign there. There are guys on here with pertronix on their 470 but not sure what dizzy they are runnin.

 

[Don S]

Re: 86 mercruiser 170 ignition problem

Just disconnect one of the white green wires, and don't let it touch anything. See if you have spark.

if no spark, you have distributor problems. Do you still have the old points setup that was in the distributor?

 

[Cynicaltrip]

Re: 86 mercruiser 170 ignition problem

ya the pertronix rep said they didnt make a kit for my prestolite dizzy...screwdown cap with a 23.75mm dizzy cam lobe....so i switched to HOT SPARK kit and it fit nicely....maybe pertronix does and rep was eh but anyhow i switched and would love to get spark now lol....any ideas fellas?....

 

[Cynicaltrip]

Re: 86 mercruiser 170 ignition problem

k don ill try that tomorrow...thanks again i appreciate it...i'll post update then...and no i dont have the points setup .....or that would of been done awhile back lol switch back to a points system and try it..

 

[dingdongs]

Re: 86 mercruiser 170 ignition problem

did you put the rotor back in???????
the spark has to get from the coil to each lead via this.

 

[Cynicaltrip]

Re: 86 mercruiser 170 ignition problem

Yes rotor is back in.....I'm stumped gonna try disconnecting white/green wire from shift interrupter tomorrow...see if that works I guess...

 

[dingdongs]

Re: 86 mercruiser 170 ignition problem

remove cap and then remove centre wire from dizzy and hold it a 1/4" off block and crank.
should be sparking 6 times per revolution of the distributer.

 

[Don S]

Re: 86 mercruiser 170 ignition problem

should be sparking 6 times per revolution of the distributer.

Uhhhhh, it's a 4 cylinder, better make that 4 times per revoluton of the rotor. Hopefully the distributor isn't turning.

 

[Cynicaltrip]

Re: 86 mercruiser 170 ignition problem

Ill try that tomorrow also good advice....I will update...

 

[Cynicaltrip]

Re: 86 mercruiser 170 ignition problem

K update time.....Pulled the cap off and disconnected coil wire off cap....held it to engine block and cranked motor...it had plenty of nice looking spark...so if i have spark firing from the coil like that does that mean my cap and rotor is bad and thats why no spark at plugs im assuming?....and i tried looking into the replacement cap for the prestolite 4cyl marine dizzy and its an elusive creature....any links to a cap and rotor would be appreciated also thanks guys!!

 

[DaveG55]

Re: 86 mercruiser 170 ignition problem

is this it?
http://marineengineparts.com/shopsite_sc/store/html/page605.html

 

[Cynicaltrip]

Re: 86 mercruiser 170 ignition problem

ya dave thats the only place i found that has screw down cap like mine. also...was wondering if anyone sold rotor by itself or good idea to get points just to have since im running electronic ignition.....also from my above post would a bad cap and rotor cause my situation ?...