1982 140hp evinrude, No Power

[teljoundi]

i have a 1982 140hp V4 Evinrude on my 18' Crestliner boat. recently the boat has had no bottom-end power when trying to take-off, even with just me in the boat it takes it about 10 to 15 seconds to gain enough speed to plane out. but after it does, it runs just fine but still doesnt hit top speed of 40mph like it used to, wot at about 30 mph. was just wondering if any one might have an idea to what it could be. had it serviced at a marine bout a month ago. said they did a tune-up and new plugs and ran it in the tank with no problems but not under load. i have replaced everything that has to do with fuel, new lines, filters, pump, everything and it still does the same thing. i always use premium fuel with an oil mix, of course, and have tried seafoam to try and maybe clean up the motor a little but still no luck. any advice would be much appreciated!!

 

[emdsapmgr]

Re: 1982 140hp evinrude, No Power

You may be losing spark on one cylinder. Check them with an inductive timing light when you are under power. You should see the same strong flashes on all 4 plug wires.

 

[cdoliver]

Re: 1982 140hp evinrude, No Power

check compression and spark. I wouldn't run this motor for extended period of time until we find the culprit.

 

[teljoundi]

Re: 1982 140hp evinrude, No Power

havent been able to get a hold timing light yet but i did a compression test and they were all good except for cylinder 1 which was bout 15 to 20 psi low. not sure if thats a big deal or not. what would cause me to lose spark? also, i just noticed a couple hours ago that my voltage meter never gets above about 11 volts or so, might be a problem. i checked the battery and its good, so im thinking maybe a voltage regulator or something. cant be the "boat" alternator cause it stays at a constant 11 volts and if it was bad the battery would die after a while.

 

[kenmyfam]

Re: 1982 140hp evinrude, No Power

havent been able to get a hold timing light yet but i did a compression test and they were all good except for cylinder 1 which was bout 15 to 20 psi low. not sure if thats a big deal or not. what would cause me to lose spark? also, i just noticed a couple hours ago that my voltage meter never gets above about 11 volts or so, might be a problem. i checked the battery and its good, so im thinking maybe a voltage regulator or something. cant be the "boat" alternator cause it stays at a constant 11 volts and if it was bad the battery would die after a while.

What were the actual compression readings ??

 

[emdsapmgr]

Re: 1982 140hp evinrude, No Power

Likely the compression when new was well over 130 lbs each cylinder. A loss of 20 lbs is significant and may indicate a problem. I'd have a look at the low cylinder. That engine has a rectifier only, which should permit the battery voltage to creep up to 14.5-15.5 volts when the engine is run for 30 minutes. If you only read 11 volts, the battery may not be re-charging from the engine. Your engine only uses the battery for a few seconds when starting, so it will take you some time to fully discharge the battery. I am suprised the engine will start with only 11 volts at the battery.

 

[kenmyfam]

Re: 1982 140hp evinrude, No Power

Would still like to see the actual compression readings and a spark test done.

 

[teljoundi]

Re: 1982 140hp evinrude, No Power

not sure what the readings were on the cylinders, the shop that did the test didnt say, just said cylinder 1 was a little low, whatever that means. another thing on the battery, i have used the boat bout 10 times this year already and the battery hasnt changed voltage since, i havent charged it or anything and it has yet to die on me or anything. also, when taking off, why would it all of a sudden decide to pick up speed after 10 seconds or so, its not like low compression in a cylinder is just ganna go away and give me full power? just some thoughts