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1990 90hp mercury

L

Lenjack

New member
Hi there people
i have a 1990 90hp Mercury and sometimes it starts and sometimes it does not start at all.
when she goes she runs perfect and keeps going without any issues.
but every now and then when I go to fire her up she won't go and seems to be no spark at the plugs
then next time she goes again
ive swapped all the leads and done spark plug test but seems no spark to spark plugs
i have notice a couple of times when I get her going it seems like it's running on only two spark plugs then when I give it a bit of gas the third one kicks in
ive had carbs done and all in sync
i did put battery cables on reverse a while ago and I've tested rectifier and its fried
can anyone out there help me please
thanx
 
Take the starter motor apart and inspect it.-----Easy to do.--------Slow cranking leads to a " no spark condition " on these systems.--------------When you have it apart ask for tips on how to inspect.
 
Well, 2 years is a long time.---------These starters are easily ruined by too much cranking !!!---------Time to do a " no money spent " inspection of your starter today.
 
Worn brushes,replace if necessary,clean everything to shiny with a fine grade paper,400 grit should do,lubricate bendix and you should be good to go.
 
Do you think that this could be the problem
i was wondering if the symptoms were more electrical or maybe the charging circuit as I no I have blown the rectifier
and that's when I started having problems???
i will check out starter motor anyway
thanx
 
Ok guys have striped and cleaned starter motor
everything looked fine with it and have bolted it back on and fired her up but still no spark
any ideas help please!!:confused:
 
If you cooked your rectifier and have run the motor with the bad rectifier it's possible that you have damaged the stator. While the windings for the ignition and the charge system are separate (circuit wise) they are co-located in the overall stator.

If you run the motor with a bad rectifier the power generated to charge the battery, having no where to go can (kinda) back up and do damage to the windings which in turn could damage the adjacent windings for the ignition side of things.

I would either have the stator tested (DVA tests are best) or test it yourself. Simple resistance tests can be done when the motor "won't start" - no continuity would indicate a bad stator.
 
Ok thank you for that information
i was thinking along those lines too
will test stator later this week and give results soon
thanks again
 
Hi I replaced the switch box and rectifier with new ones and bingo she fire up and ran good
hopefully this has solved it
thanx for all the help really aprieciated
 
Hi I am going to replace new rectifier with regulator/rectifier combined. I have done some research on this
and cdi have got them. Apparently this will be better for electricals and battery.
can anyone confirm this. Thanks
 
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