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1979 evinrude doing funny things

R

rick peppers

Member
hi everyone total forum noob here so excuse my ignorance please

recently bought a boat that has a 1979 Evinrude 115 on it

we ran it on muffs and I thought it ran well...………...well I put it in the water and it proved me an idiot!!

back story has been sitting 3 years with old fuel in it

put new fuel in it and ran it. it ran super rough sometimes on 2 cylinders and sometimes on 3 after I got it moving it roared to life on all 4 cylinders

when I idle ba ck down it drops to 2/3 cylinders again until I have had the throttle tapped for a few minits then boom. 4 cylinders

I checked compression and it is a touch low (100 in all four) but from what I have read, even though that is far from ideal, it is still acceptable, at least to finish the season out.

I just replaced the spark plugs and am planning on testing it some more in the morning as it still sounds rough on muffs

can you gentleman please give me some sort of an order in which to start checking things on the motor so I can iron it out?

and I want to thank all you in advance as I know im not the first ignorant noob to ask the same dumb questions
 
Boobie said:
Do the carbs on all 4 and go from there.
Click to expand...
Yep, I would question any carb that has sat for 3 years, especially if old fuel was left in the bowls to evaporate. Just to check things off the list I would test spark just to verify it's good.
 
On this page.----Click on " engine diagrams "----Then on line with 1955 - present.----just a few clicks to find it on the list for 79 model 115 HP.
 
so a little update.....

I pulled the carbs and am inspecting them and cleaning although they are surprisingly clean to begin with

I checked that each coil pack is producing spark and they are all doing well

heres a question.. when it has sat I notice that there is no fuel in the primer bulb and when I squeeze it repeatedly it doesn't bring any fuel in and or through? will a bad check valve in the primer bulb interrupt fuel flow? or is this indicative of a rotted fuel line somewhere in between the tank and the engine? there isn't really any gas odor like its leaking.
 
rick peppers said:
Heres a question.. when it has sat I notice that there is no fuel in the primer bulb and when I squeeze it repeatedly it doesn't bring any fuel in and or through? will a bad check valve in the primer bulb interrupt fuel flow?
Click to expand...

If the anti siphon valve at a built tank is stuck open or non existent... and the fuel primer bulb has a bad check valve, the fuel can siphon backwards into the tank when the engine is not running.

A bad check valve in the primer bulb even when everything else is okay would make it difficult to have the bulb draw fuel from the tank.

If you have not yet manually cleaned the four brass high speed jets in those carbs, do so now.

With all spark plugs removed, the spark should jump a 7/16" gap with a strong blue lightning like flame... does it? NOTE that the 7/16" gap is important.
********************
(Spark Tester - Home Made)
(J. Reeves)

You can use a medium size philips screwdriver (#2 I believe) inserted into the spark plug boot spring connector, then hold the screwdriver shank approximately 7/16" away from the block to check the spark or build the following:

A spark tester can be made with a piece of 1x4 or 1x6, drive a few finishing nails through it, then bend the pointed ends at a right angle. You can then adjust the gap by simply twisting the nail(s). Solder a spark plug wire to one which you can connect to the spark plug boots, and a ground wire of some kind to the other to connect to the powerhead somewhere. Use small alligator clips on the other end of the wires to connect to ground and to the spark plug connector that exists inside of the rubber plug boot.

Using the above, one could easily build a spark tester whereas they could connect 2, 4, 6, or 8 cylinders all at one time. The ground nail being straight up, the others being bent, aimed at the ground nail. A typical 4 cylinder tester follows:

..........X1..........X2

.................X..(grd)

..........X3..........X4

This can obviously be modified to a 6 or 8 cylinder setup tester.
********************
 
rick peppers said:
I pulled the carbs and am inspecting them and cleaning although they are surprisingly clean
Click to expand...

Did you run a wire through each orifice? A clean bowl doesn't necessarily mean the fuel circuits for high and low speed are clear.

rick peppers said:
I checked that each coil pack is producing spark and they are all doing well
Click to expand...

"Doing well" has a very specific measurement. You need to follow Joe's spark test method and report back if you get a 7/16" spark jump on each cylinder. This is how you ensure spark is sufficient when the engine is under load.

rick peppers said:
heres a question.. when it has sat I notice that there is no fuel in the primer bulb and when I squeeze it repeatedly it doesn't bring any fuel in and or through? will a bad check valve in the primer bulb interrupt fuel flow? or is this indicative of a rotted fuel line somewhere in between the tank and the engine? there isn't really any gas odor like its leaking.
Click to expand...
Sounds like you have a fuel delivery problem. The first easy test is to pull off the primer bulb and hold a finger over the inlet side. Squeeze the bulb and see if you feel suction against your finger. Next, squeeze and hold the bulb, place your finger over the outlet, then take your hand off the bulb. You should feel suction against your finger. If you don't feel suction on either one then you most likely have a bad bulb. Since the boat has sat I would suggest also check all fuel lines to make sure they're okay.

KJ
 
kevinj said:
Did you run a wire through each orifice? A clean bowl doesn't necessarily mean the fuel circuits for high and low speed are clear.



"Doing well" has a very specific measurement. You need to follow Joe's spark test method and report back if you get a 7/16" spark jump on each cylinder. This is how you ensure spark is sufficient when the engine is under load.


Sounds like you have a fuel delivery problem. The first easy test is to pull off the primer bulb and hold a finger over the inlet side. Squeeze the bulb and see if you feel suction against your finger. Next, squeeze and hold the bulb, place your finger over the outlet, then take your hand off the bulb. You should feel suction against your finger. If you don't feel suction on either one then you most likely have a bad bulb. Since the boat has sat I would suggest also check all fuel lines to make sure they're okay.

KJ
Click to expand...

thanks I will do a proper spark test in the next day or 2.

Another random question. Is running the engine in a barrel of water considered “under load”
 
Running in a barrel is not a load.------There will be too much exhaust in the water and at full throttle you would have a short dirty shower.-----The motor will empty the barrel in just seconds !!
 
rick peppers said:
Question. Is running the engine in a barrel of water considered “under load”
Click to expand...

Under "load" normally indicates that the engine is in gear with a fair amount of throttle applied. This can only be performed if the engine is equipped with a "Test Wheel". Any attempt to do with a propeller will result as per post #19.

However... in a barrel, as long as the water level is above the water pump area and close to the level as if the engine was on a boat sitting still (neutral) in the water.... normal running back pressure would exist in the exhaust system which would allow precise carburetor adjustments and idle settings.

Curious as to why you were asking that question??
 
so a little update... I bought a spark tester and all four cylinders are jumping 7/16" with a blue spark

I disassembled the carbs and cleaned all orifices and jets with wire carb cleaner and compressed air inside of carba all look good

I started it on the muffs and it still is not sounding too convincing. I do plan on taking it to the lake tomorrow evening and seeing what it does under load

oh I also replaced the fuel pump gor good measure

I have a new question.. the battery is dated 4/15 but has no problem cranking over the motor but I put on a charger and itsays its 25% charge....will a bad battery affect how the boat runs? maybe stealing too much power from the ignition system, etc...?
 
also i forgot to mention that when its running it smokes ALOT i know 2 strokes smoke but it seems excessive like it fills my garage with 2 stroke smoke, could this all be related to old fuel still hanging on inside the lines and such even though i have replaced the fuel with fresh high octane at a 50:1 mix?
 
That's starting to sound like a carb needle valve tuning issue. You could be running really rich, hence the extra smoke. Try tuning that valve and see if that helps
 
Yep, typically they are easy to access and are flatheads. It's basically a long, thin cone on the end of a screw. Thread it in to restrict flow and out to increase
 
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