Hello, I have searched through the forums and am stumped on my problem. '74 85hp on a 16' 74 Larson. Pretty much cherry everything. Long story short, loss of power at half throttle and above. I have replaced the fuel tank, fuel lines, fuel pump, rebuilt the carbs with new floats, 4 new coils, and a new power pack. Checked the compression yesterday and all four were at 125psi. Idles like a champ on the ears and in the drink but when I open her up she boggs down and I only get up to 20mph when she used to go 37mph. No overheating no fuel leaks no signs of anything, just no power. I haven't touched the timing or anything since I got the boat. I did read out the stator and it read within limits so I don't think it is that. It is 31 years old but looks almost new. Old fellow next door wanted me to have it so I took it although I was hesitant. Cleaned it up and she ran like a top until a couple of weeks ago. I replaced the above items mostly for gp since she is 31 years old. Frustration is setting in and a for sale sign might be in order if I can't get her right! Thanks for your suggestions!Mark (Seamule Captain)
Welcome aboard Cap!Next time out, take a timing light and at WOT, connect the light to each spark plug wire. I know, you've replaced everything but the kitchen sink.....but the sink is still there. I had a similar problem on my 90. Great fire when doing spark test but in the water it was a pig......found that I had #2 cylinder blanking out on me.Just some other things to check.....check the grounds on the power packs. A lose ground will cause night mares....in fact, check them all. Make sure they are clean and tight. Make sure the amphenol connectors (that's them rubber connectors) are making good contact and all the pins are in all the way. (That's what was wrong with mine...)Check the carbs throttle linkage. Make sure the throttle plates are opening at the same time and are coming all the way open. Don't put the sign on yet Mark....we can save it!
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When in doubt...use the manual
Rayland, Ohio....Along the Muddy Banks of the Mighty Ohio River.
Thanks OBJ! I'm not sure what you mean by the amphenol connectors. Are you talking about the powerpack connections(mine just has screw connectors, no pins like a cannon plug, just screw terminals) or are you talking about the spark plug boots? I did find that my #4 plug was wet fowled when I took it out this evening. I'm using the gapless plugs. I'll try the timming light as well and let you know what happens. The neighbors think I have a race boat when it's on the ears! I wish it ran as good in the water! Thanks again!
Sorry about the connectors Mark...your right...no conectors (amphenol). But do check the grounds. Just curious...have you checked spark to each cylinder? You can do it with a nail....10 penny works good. Just cut the head off and shove it in the spark plug boot. Hold the pointed end about 7/16" from a clean engine ground and have someone crank the engine. You should see a hot thick lighting like spark on all cylinders. OH...hold the nail or spark plug wire with insulated pliers. Nasty shock....nasty.
__________________
When in doubt...use the manual
Rayland, Ohio....Along the Muddy Banks of the Mighty Ohio River.
Well I checked the spark by removing the plug boots with my hands (I'm used to the shock) and noticed that I had a difference in rpm in all but number 4. Thats when I decided to (after reading and searching the forums) change all the coils because some had cracks and would shock me before I even got to them! So I did replace them all, and the powerpack and the rectifier cause it had a cracked wire too then I thought just to be sure I'll rebuild the carbs while I'm at it. All this was done last week and yesterday I fired it up on the ears and all was great. Noticable rpm diff when each plug wire was removed, plugs even burn great so I thought better test it in the water now. Lauched it this afternoon, fired right up idled perfect warmed up about 4 mins and hit it. Jumped out of the water like it should then settled into the same bogg down like it did before the coils,pwrpack changeout. I checked the linkage it looked fine, ran it with the cover off and visually checked everything and didn't see any weird stuff at all. Checked the plugs when I got home and saw #4 wet. I guess I'll do a spark test tomorrow and I'll let you know. I'll look at the grounds again as well on the power pack. Maybe I got a bad coil from the dealer who knows. Thanks for your help and I'll try what you said.
Well I ran another spark test and found that #1 is dead. I swapped the coil with #3 and still no spark. Since I replaced everything else I guess it's time to replace the stator and pick-up eh? I hate dumping more into this boat motor being that it is 31 years old. But if I do that, I will have replaced it all but the pistons. What the hey. Thanks for your help!
One other question. When I read the sensors and the pick-up they were within the specified range. All resistance checks were perfect. I don't have a tester and was reading a thead here about bending the sensor toward the crank, think this would work or should I still replace the stator and pick-up or am I missing something else?
Update on the spark problem. I ordered a new stator and timer base. Replaced them both and no fire at all! So I swapped the old timer base with the new one, kept the new stator in, and she fired right up. Launched it and she ran with a slight miss at full throttle. Throttled down and she shook bad like I had busted a crank or something then died. DIW! I paddled for 2 hours before getting a tow from a jet skier. I was hot to say the least! Anyway I was ready to sell the boat and part out the motor but before I did I called the company that sent me the timerbase and they said they would replace it. In the mean time I was sure I had busted something internal so I went on ebay and bought another boat with a 90hp Evinrude to replace the 85hp. Well I have to pick up the new boat in a day or two and this afternoon the new timer base showed up. I thought well I'll throw in the new base just for grins and when I pulled off the flywheel I found the the key had sheered in half! Blow me away! Well I put in the new timer base and a new keyway and she fired right up. Launched her and she ran like a top! Soooo now I have two boats, a broke bank account and a ticked off wife. But hey I learned how to not trust an ohm meter! Thanks for your help! P.S. Anyone wanna buy one!LOL!!!!!!!
85hp Evinrude power loss
Mark (Seamule Captain)
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