1978 evinrude 115 not getting full throttle

[beckea2]

This is my first post I have just recently bought this boat and it fires up and runs very strong but when I give it full throttle it tops out at 2300 rpm there is NO bogging, sputtering etc. it runs smooth and strong to that point I feel like it is just an adjustment but I don'y know much about outboards so I would appreciate any help I can get. Thanks Adam

 

[ezeke]

Re: 1978 evinrude 115 not getting full throttle

The tachometer is probably set incorrectly. See if you can borrow a inductive tachometer and verify the reading.

There is no internal control on the system that would slow the engine, so it should run much higher unless it is over-propped.

 

[beckea2]

Re: 1978 evinrude 115 not getting full throttle

I really doubt the rpm is wrong because the speed on gps is 10 mph at about 2300 rpm and it won't go any faster is it possible that the spark isn't advancing

 

[ezeke]

Re: 1978 evinrude 115 not getting full throttle

Sure, but you said it was running fine? What is the boat? What is the prop?

 

[beckea2]

Re: 1978 evinrude 115 not getting full throttle

Sorry it does run fine but with it at full throttle it levels off at around 2300 rpm like there is some sort of govenor on it. I'm not sure of the prop but I did speak to the person I bought it off and he said it would run 42 mph last year with the same prop that is on it it is a 16 foot silverline ski boat.

 

[ksubigbuck]

Re: 1978 evinrude 115 not getting full throttle

Yes, you should check your spark advance as well as the condition of your fuel system. Could be carbs are clogged, or it could be that they are out of sync. It could also be something simple like a clogged fuel filter, collapsed bulb, collapsed fuel line, or an air leak somewhere. I'd start with the simple stuff like fuel lines, filters, and bulbs first.

Hunter

 

[splitshot]

Re: 1978 evinrude 115 not getting full throttle

check my post i havent figured it out but mine will only do 3000 rpms..it might give you some ideas...subject is "still no wot rpms".....

 

[beckea2]

Re: 1978 evinrude 115 not getting full throttle

ok I will check that stuff but I've had fuel problems with my seadoo before and this does not seem to me to be fuel and ive already checked the fuel filter and it was clean

 

[wilde1j]

Re: 1978 evinrude 115 not getting full throttle

All kinds of things to check (air leak on suction side of pump, bad fuel pump, crap on the fuel pickup screen, bad tank vent, etc, etc.). Have you tried a different fuel tank? Have you tried squeezing the primer bulb when at 2300 RPM and/or activating the choke/primer?

An OEM shop manual would be very helpful also.

 

[wavrider]

Re: 1978 evinrude 115 not getting full throttle

I have the same engine.

I would first check spark on all four plugs,
Could be a combination of many things but lets eliminate the easy ones first.check spark, get a spark tester at your local auto store, arounf $8.00

Wire brush or sand off the paint on the tip of the adjusting screw, that way you get a good ground to check your spark. Set tester at 7/16 gap, should be good blue spark.

If you do get good blue spark on all four, then pull compression check. you never stated anything about water intrusion or running rough but always possibility of blown head gasket.

spark check good, compression check good, then look at fuel. fuel lines, fuel pump, fuel filter.

Mine was doing the same thing when I first got it, ended up being a weak fuel pump, replaced it and runs fantastic. Let us know what you find on the tests and will go forward from there.