I recently bought a 1984 90hp Mercury from a fellow who had it at a Marine dealer and couldn't make it run right.
I checked compression, it was ok all cylinders 145-150 psi(he told me #2 was low).
I checked spark and #4 had no spark. I knew where a 150 was sitting in a barn so we went and got the whole boat(another story for later) and stole the switchbox from it. After changing the switchbox I had good spark on all cylinders.
The Marine place had rebuilt the carbs and replaced the starter and water pump, and ???. At this point it would start and run VERY rich but it sounded like all cylinders hit. After a little head scratching I pinched off the enrichener line and it cleared out and ran fine. The switch was shorted and had power to the enrichener all the time so I disconnected it(later installed a momentary switch as a stopgap).
ANYWAY...
The guy had mentioned that the whole reason that he took the boat to the marine mechanic was because it wouldn't run much past half throttle. I had read on here prior to buying this motor that if the rectifier was bad it could cause a problem like this. This is the only reason I bought the motor as the guy is a (truck) mechanic and had it at the Marine mechanic and couldn't make it run so the probability of making it run wasn't that good(oh.. and he delivered it to my shop for 300$ and brought the controls and harnesses ).
I unhooked and taped off the stator yellow wires as I figured that That may have been the problem all along and didn't want to have that causing problems.
I had dropped the motor on an old tri-hull of my Dad's and ran it out to the lake and it ran fine-41mph!. Smooth idle 650 in gear and about 850 in neutral.
Cool, So I quickly took off the 2 35hp Evinrudes on my fishing boat and replaced them with the MERC TOWER OF POWER! I also hooked up the stator yellow wires and ran it in the tank-charged ok and ran fine.
Took it out for a lake test and VIOLA..runs bad. I disconnected the yellow wires and it runs great! Steady reliable 35+mph and saw 37 once. Sucks gas tho'
OK...here's the question(s):
Is the running problem the rectifier(it tests ok), or the stator(the yellow wires are crumbling all other stator wires ok).
How do I test it? It ohms out good except that there is about 175 ohms to ground on either yellow lead. Kin of weird though as it is about 3kohm all hooked up.
What is a DVA meter and is there an adapter I can make for my Fluke?
I need a switchbox(or one for the 150 I stole it from)-should I go ahead and replace the stator, switchboxes,trigger, and rectifier? Try a rectifier and a switchbox? Opinions?
Is CDI the best?
I think...It needs a stator. Switchboxes would be nice and a trigger??... may as well if I do a stator. Rectifier probably too.
If it would run with just a rectifier then I would probably do that for a while to see how good the motor is(it is clean and works nice). I have one fishing trip coming up in late SEPT. but it is only 2 days. I might just run it the way it is for now too.
I can buy trigger,stator,and switchboxes and a switch and rectifier all CDI (except for switch) for around 500$.
PS.
I am a mechanic with most of an electronics engineering degree,I own an auto repair shop where I am head mechanic,only mechanic,uhh..only employee and am not made of money. That's why I have a 1979 Lund Mr. Pike 189 fishing boat and buy 30 year old Mercurys to upgrade my motor(s).
I sent the guy bought the motor from this pic the day after he delivered it(He was not happy with the boat mechanic):
I checked compression, it was ok all cylinders 145-150 psi(he told me #2 was low).
I checked spark and #4 had no spark. I knew where a 150 was sitting in a barn so we went and got the whole boat(another story for later) and stole the switchbox from it. After changing the switchbox I had good spark on all cylinders.
The Marine place had rebuilt the carbs and replaced the starter and water pump, and ???. At this point it would start and run VERY rich but it sounded like all cylinders hit. After a little head scratching I pinched off the enrichener line and it cleared out and ran fine. The switch was shorted and had power to the enrichener all the time so I disconnected it(later installed a momentary switch as a stopgap).
ANYWAY...
The guy had mentioned that the whole reason that he took the boat to the marine mechanic was because it wouldn't run much past half throttle. I had read on here prior to buying this motor that if the rectifier was bad it could cause a problem like this. This is the only reason I bought the motor as the guy is a (truck) mechanic and had it at the Marine mechanic and couldn't make it run so the probability of making it run wasn't that good(oh.. and he delivered it to my shop for 300$ and brought the controls and harnesses ).
I unhooked and taped off the stator yellow wires as I figured that That may have been the problem all along and didn't want to have that causing problems.
I had dropped the motor on an old tri-hull of my Dad's and ran it out to the lake and it ran fine-41mph!. Smooth idle 650 in gear and about 850 in neutral.
Cool, So I quickly took off the 2 35hp Evinrudes on my fishing boat and replaced them with the MERC TOWER OF POWER! I also hooked up the stator yellow wires and ran it in the tank-charged ok and ran fine.
Took it out for a lake test and VIOLA..runs bad. I disconnected the yellow wires and it runs great! Steady reliable 35+mph and saw 37 once. Sucks gas tho'
OK...here's the question(s):
Is the running problem the rectifier(it tests ok), or the stator(the yellow wires are crumbling all other stator wires ok).
How do I test it? It ohms out good except that there is about 175 ohms to ground on either yellow lead. Kin of weird though as it is about 3kohm all hooked up.
What is a DVA meter and is there an adapter I can make for my Fluke?
I need a switchbox(or one for the 150 I stole it from)-should I go ahead and replace the stator, switchboxes,trigger, and rectifier? Try a rectifier and a switchbox? Opinions?
Is CDI the best?
I think...It needs a stator. Switchboxes would be nice and a trigger??... may as well if I do a stator. Rectifier probably too.
If it would run with just a rectifier then I would probably do that for a while to see how good the motor is(it is clean and works nice). I have one fishing trip coming up in late SEPT. but it is only 2 days. I might just run it the way it is for now too.
I can buy trigger,stator,and switchboxes and a switch and rectifier all CDI (except for switch) for around 500$.
PS.
I am a mechanic with most of an electronics engineering degree,I own an auto repair shop where I am head mechanic,only mechanic,uhh..only employee and am not made of money. That's why I have a 1979 Lund Mr. Pike 189 fishing boat and buy 30 year old Mercurys to upgrade my motor(s).
I sent the guy bought the motor from this pic the day after he delivered it(He was not happy with the boat mechanic):
