1979 Evinrude 115hp ran great, now....not so much (runs then dies).

[Larry Tate]

hey guys i got a 1979 rude 115 hp. the motor ran GREAT for about 2 months now. took it far in the lake (champlain, probably 16 miles round trip) and on the way back i noticed a lack of power. at first it was minor, but it got to where i would open the throttle in gear and it was like i was shutting the key off. got it back on the trailer, ran it in the driveway with a hose on it and it was like clockwork... i would raise the cold start halfway, choke it, it starts, choke off, runs for like 5 more seconds and dies. please please if anyone can help much appreciated...post back if u need more information. thanks again u guys rock

 

[gjmsd]

Re: 1979 Evinrude 115hp ran great, now....not so much (runs then dies).

Almost sounds like a fuel restriction. Had a similar problem with a dirt bike once. When it sits, fuel will fill the bowls and it'll run good but the fuel can't keep up and it'll eventually run lean (or out). I'd go through it carefully.

 

[Larry Tate]

Re: 1979 Evinrude 115hp ran great, now....not so much (runs then dies).

so a little update...got it to idle nice on the muffs so i brought it to the river. once i got it off the trailer, i dropped the hammer to make sure it had some "get up and go", and it did. jumped out of the hole about 5 times (could'nt hold full throttle cause i was in the river) so i was satisfied. as i idled towards the lake it was fine also. passed the last guy fishing and went to hit it- same thing as before. the rpm's were dropping as i opened the throttle. luckily from where i was i was able to putt it home. when i got it back to the trailer i started it up again and lifted the cold start to try to keep it running then it died and would not even start. went home, pulled the plugs, sprayed em off (didnt seem too dirty) and put em back in and its back to idling nice. wtf???!? i got it at work today im gonna let it idle on the hose for a looong time and ill post back.

 

[Joe Reeves]

Re: 1979 Evinrude 115hp ran great, now....not so much (runs then dies).

Test the warning horn.... Engine NOT running, key in the ON position, ground out one of the TAN wires you see protruding from the heat sensors at the cylinder head(s). This completes the horn circuit and the horn should sound. Does it?

When you apply the throttle after clearing the no wake zone.... Does the engine ever hit the full throttle range? How long after applying full throttle do you start to lose power? Does the fuel primer bulb have a tendency to be drawn flat?

Spark plugs should be Champion QL77JC4 plugs gapped at either .040 or .030, whichever works best for you.

With the s/plugs removed, the spark should jump a 7/16" gap with a strong blue lightning like flame... a real SNAP! Does it? NOTE.. checking spark by using the spark plugs is a waste of time, the 7/16" gap is important.

 

[Larry Tate]

Re: 1979 Evinrude 115hp ran great, now....not so much (runs then dies).

thanks for the reply joe. about the warning horn...my motor is a 1979 im not sure if it is equipped with that but i will check. i know the compression is even on all cylinders (i suspected i cooked it as first).

when i go to hit full throttle, its like the motor will stand up for a second and then sit back down...as if it wants to go but just cant.the other day i was trolling at about 3 or 4 mph for about 10 mins. the i attempted to put it on plane, sputtered almost immediately and would not revv higher than 2 or 3000 rpms. then it got so bad where it would not run. choke on half cold start it would fire up, but then die as i attempt to put it in gear.

my spark plugs are Champion L78V- they are also the flat-top style and do not have a gap. is that a problem?

i will also test the spark once i can get my hands on a tester. i am very mechanically inclined just not sure where to go as i know it can be many different things.

one more thing...its a 115 rude on a 16 ft starcraft css and i've only gotten it to about 41 mph so i think maybe it has always been a little bogged down. my prop is 13x19. thanks for the replies again guys.

 

[Larry Tate]

Re: 1979 Evinrude 115hp ran great, now....not so much (runs then dies).

also...i have had it running today for almost a half hour on the muffs...revvs up and down, idles just right. i know that its not the same as being in the water because there is no resistance on the prop/crank, but i figured it may be helpful.

 

[Joe Reeves]

Re: 1979 Evinrude 115hp ran great, now....not so much (runs then dies).

thanks for the reply joe. about the warning horn...my motor is a 1979 im not sure if it is equipped with that but i will check. i know the compression is even on all cylinders (i suspected i cooked it as first). my spark plugs are Champion L78V- they are also the flat-top style and do not have a gap. is that a problem?

It would help to know for sure what the compression is on all cylinders.

The spark can be checked by having a medium size philips screwdriver inserted into to spark plug boot spring connector, then hold the shank of it that approximate 7/16" away from the block.

That engine absolutely has the overheat horn warning system. It's the only warning you'll receive should the engine begin to overheat. Normal circuitry is.... TAN wire from the wiring harness to the horn's spade terminal closest to the horn's built in black ground wire (should that black ground wire exist). Then a Purple wire running from the ignition switch's "A" terminal to the remaining spade terminal of the horn. If the black ground wire exists, the horn would be the latest style horn that has the single beep warning when the key is turned to the ON positon.

Those L78V plugs actually have no heat range and are prone to fouling. You're better off using the QL77JC4 plugs.

On a flushette, it may sound like the engine's running fine when actually it is not. The compression and spark test is needed to decide if the problem is internal or an ignition one, and if neither... that'll lead us into the fuel area.

The mention you made... (i suspected i cooked it as first)... What does that mean and what did you do about it?

 

[Larry Tate]

Re: 1979 Evinrude 115hp ran great, now....not so much (runs then dies).

the compression was between 120 and 145 approx...i do not remember the exact readings for all the cylinders (i was looking for one to be under 100 or something like that)

i will get new plugs because the ones in there now are pretty fouled, however it would be too easy if that fixed my problem!

i suspected it overheated at first because this motor was great. ive used and repaired a lot of motors for boats by now, and this one is solid. thats why i figured it was just overheating, it was one of the hottest days so far this year and it was out for about 45 mins of WOT. all that came of me thinking this was when i got it home the first thing i did was check to see my compression was still there and even... no use posting about scrap metal. i will check the spark asap and post back

 

[Larry Tate]

Re: 1979 Evinrude 115hp ran great, now....not so much (runs then dies).

ok quick update... i just had it running at idle on the hose (nice, strong idle too. this thing is driving me nuts...) and i pulled off each plug one at a time, they all made a difference in the idle speed, and they all seemed to make about the same amount of difference as well. all 4 are sparking at idle.

 

[Joe Reeves]

Re: 1979 Evinrude 115hp ran great, now....not so much (runs then dies).

the compression was between 120 and 145 approx...i do not remember the exact readings for all the cylinders

If that's accurate, you have an internal problem (25 psi difference). When you have time, take another reading and jot down the individual cylinder readings. You're probably aware of it but just in case.... standing in back of the engine, facing the spark plugs, the cylinders are numbered as follows.

2.....1

4.....3

 

[Larry Tate]

Re: 1979 Evinrude 115hp ran great, now....not so much (runs then dies).

#2- 130 lbs
#1- 130 lbs
#4- 125 lbs
#3-120 lbs

so yeah when i checked it the other day i was sorta in a pissed off rush- was just checking to see it one was waay off. i was actually suprised to see they are all in as close of a range as they are. if things could be any worse, i work at a bait and tackle shop off of lake Champlain, and all the guys are telling me lakers, salmon and browns are biting like crazy :facepalm:

 

[hidef]

Re: 1979 Evinrude 115hp ran great, now....not so much (runs then dies).

Have you installed the QL77JC4 Spark plugs as recommended? Checked the spark with a tester set at 7/16"? When was the last time the water pump impeller was replaced? When was the last time carbs were cleaned? Have checked the thermostats?

 

[Larry Tate]

Re: 1979 Evinrude 115hp ran great, now....not so much (runs then dies).

im getting the plugs tomorrow the plugs are all sparking but i still have to use an actual tester to see if its good. the impeller works fine nice stream out of the tell tale and exhaust...not sure when the last time the carbs were cleaned (thats a no-brainer i was wondering if there is other stuff i should do first) and the water coming out is hot so the t stats should be working.

 

[Larry Tate]

Re: 1979 Evinrude 115hp ran great, now....not so much (runs then dies).

ok think i got it... the old fuel lines were old but looked ok... replaced em anyway. the main thing that was no good was they were all attached with zip ties- no hose clamps. put new fuel line and hose clamps on eveything and it seems to have fixed the problem. i was skeptical at first, but when it was on the trailer i noticed no fuel had dripped out from the engine housing, which usually happens when on the trailer. thanks to all the guys who replied and helped me out! on another topic, i got a lower unit seal kit coming for this pig, will it be hard very hard or not so hard? thanks again guys.