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Author Topic:   Anyone Knowledgable-Mid Eighties Merc 90

A Li Volsi posted 08-09-2001 11:01 AM ET (US)
I have a mid eighties Merc-90 on my 16 footer
and have have a problem with acceleration. When comming off idle and accelerating she bogs down-like the accelaerator pumps are bad or the choke is on. Used to get it up to about 3000 rpm and she we start to die out.I have had the electronics checked and replace an ignitor pack. First run out, she was like a new engine -up to 4400 rpm. The week later same problems-but this time she won't go past 1800 rpms. Hate to keep paying the mecahanic to keep guessing -anyone-HELP!! (fishing season is getting away from me!.
lhg posted 08-09-2001 12:27 PM ET (US)
I have a pair of these in-line 6's on my Outrage. Is the engine simply dying out and quitting as you hit the 1800 rpm range? If so, it's carb idle adjustment jets, or, worse, bad compression requiring a re-build.
If the engine just won't go over 1800, it could be a stator. Redline for this engine in the 90-HP version is 5000.
A Li Volsi posted 08-10-2001 09:51 AM ET (US)
lhg-The motors sounds as if it either the chokes came on or it just isn't getting gas. As I mentioned the first time it was one ignitor pack causing one plug not to fire and it would get ,out as if starving around 1800 rpm. Compression great, and fuel delivery is good-I keep thinking electronics. (what ever happened to old points and condensers!)
A Li Volsi posted 08-10-2001 09:56 AM ET (US)
lhg-Sorry bad editing on last post-should read as follows-
The motor sounds as if it either the chokes came on or it just isn't getting gas. As I mentioned the first time it was one ignitor pack causing the sixth plug not to fire and it would get to about 3000 rpm, then it ran great for one outing and now she dies around 1800 rpm. Compression great, and fuel delivery is good-I keep thinking electronics. (what ever happened to old points and condensers!)
Bigshot posted 08-10-2001 10:16 AM ET (US)
Had the same problem with a 115. If I nailed it from the idle it would run like a raped ape all the way to 5400. If you dropped below 38-4000 it would almost die, etc. Same thing with getting on plane slowly. Thought it was carbs, rebuilt twice and then tried a another set, no dice. Replaced stator, trigger, coils, rectifier, regulator, power packs, removed mercury switch(try that), inspected exhaust,etc. NOTHING! Reeds were good, comp was good, everything checked out. I finally sold the POS. It always started and ran but never right. Came to the conclusion that maybe 120's is too low on comp for this engine? or I had a crankcase seal leak. The latter is ost logical. Ran like it had bad reeds but they were Ok, had to be sucking air from somewhere in the block. Tower of Power baby(when it runs) Good Luck but do NOT start replaving all th electronics for nothing.
Clark Roberts posted 08-10-2001 11:06 AM ET (US)
Check the fuel pump! Also you say it acts as if choke plates are closed... all three are mechanically linked so check to see if all is working correctly and linkage hasn't slipped... etc... check fuel lines, filters, connections and connectors... check for water in gas... drain carbs etc...etc...etc... change fuel tanks first! Borrow a portable 6 gal (if you don't have one) complete with squeeze ball, hose and connector.. run with fresh gas and see if problem goes away... Good luck.. Clark... The Conch Bonker
lhg posted 08-10-2001 12:39 PM ET (US)
If the engine is "pooping out" at 1800RPM as you accelerate, carb low speed jets are adjusted too lean. Or something is wrong with the overall fuel delivery system, per Clark. Take it in for Mercury service.

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Author	Topic: Anyone Knowledgable-Mid Eighties Merc 90
A Li Volsi	posted 08-09-2001 11:01 AM ET (US) I have a mid eighties Merc-90 on my 16 footer and have have a problem with acceleration. When comming off idle and accelerating she bogs down-like the accelaerator pumps are bad or the choke is on. Used to get it up to about 3000 rpm and she we start to die out.I have had the electronics checked and replace an ignitor pack. First run out, she was like a new engine -up to 4400 rpm. The week later same problems-but this time she won't go past 1800 rpms. Hate to keep paying the mecahanic to keep guessing -anyone-HELP!! (fishing season is getting away from me!.
lhg	posted 08-09-2001 12:27 PM ET (US) I have a pair of these in-line 6's on my Outrage. Is the engine simply dying out and quitting as you hit the 1800 rpm range? If so, it's carb idle adjustment jets, or, worse, bad compression requiring a re-build. If the engine just won't go over 1800, it could be a stator. Redline for this engine in the 90-HP version is 5000.
A Li Volsi	posted 08-10-2001 09:51 AM ET (US) lhg-The motors sounds as if it either the chokes came on or it just isn't getting gas. As I mentioned the first time it was one ignitor pack causing one plug not to fire and it would get ,out as if starving around 1800 rpm. Compression great, and fuel delivery is good-I keep thinking electronics. (what ever happened to old points and condensers!)
A Li Volsi	posted 08-10-2001 09:56 AM ET (US) lhg-Sorry bad editing on last post-should read as follows- The motor sounds as if it either the chokes came on or it just isn't getting gas. As I mentioned the first time it was one ignitor pack causing the sixth plug not to fire and it would get to about 3000 rpm, then it ran great for one outing and now she dies around 1800 rpm. Compression great, and fuel delivery is good-I keep thinking electronics. (what ever happened to old points and condensers!)
Bigshot	posted 08-10-2001 10:16 AM ET (US) Had the same problem with a 115. If I nailed it from the idle it would run like a raped ape all the way to 5400. If you dropped below 38-4000 it would almost die, etc. Same thing with getting on plane slowly. Thought it was carbs, rebuilt twice and then tried a another set, no dice. Replaced stator, trigger, coils, rectifier, regulator, power packs, removed mercury switch(try that), inspected exhaust,etc. NOTHING! Reeds were good, comp was good, everything checked out. I finally sold the POS. It always started and ran but never right. Came to the conclusion that maybe 120's is too low on comp for this engine? or I had a crankcase seal leak. The latter is ost logical. Ran like it had bad reeds but they were Ok, had to be sucking air from somewhere in the block. Tower of Power baby(when it runs) Good Luck but do NOT start replaving all th electronics for nothing.
Clark Roberts	posted 08-10-2001 11:06 AM ET (US) Check the fuel pump! Also you say it acts as if choke plates are closed... all three are mechanically linked so check to see if all is working correctly and linkage hasn't slipped... etc... check fuel lines, filters, connections and connectors... check for water in gas... drain carbs etc...etc...etc... change fuel tanks first! Borrow a portable 6 gal (if you don't have one) complete with squeeze ball, hose and connector.. run with fresh gas and see if problem goes away... Good luck.. Clark... The Conch Bonker
lhg	posted 08-10-2001 12:39 PM ET (US) If the engine is "pooping out" at 1800RPM as you accelerate, carb low speed jets are adjusted too lean. Or something is wrong with the overall fuel delivery system, per Clark. Take it in for Mercury service.