1979 15 hp Evinrude

[craigrs8271]

Long story short, have new coil, power pack,plugs,carb. kit & all new fuel system gas tank hoses etc.... The motor fires up great Idles great as soon as you take off it runs for about 10 seconds & then starts to gut out. Unless you pull out the choke 1/4 of the way it takes back off & runs GOOD. I say GOOD cause ,to me it seems it could have a little more . It will take the boat to a plain across the water but just seems like it might have a little more with the choke pushed the rest the way in.
CAN ANY ONE HELP ????

Another question I have is......
I have this 15 hp Evinrude on a 13' Boston Whaler, not a big boat!!!
This motor should push this boat along pretty good. I am 6'3" & 280 lbs, to get this boat to a plain quicker is there any changes I can make besides head towards the front of the boat. Maybe the prop. pitch or size?? It has a 9 1/2x10 pitch right now..
ANYONE ??????
thanx
craig

 

[DJ]

Re: 1979 15 hp Evinrude

You said "coil". Is there more than one?

Your choking the engine and it runs better suggests it is leaning out. Perhaps a leak in the fuel pump diaphram?

Did you repalce the carburetor to intake manifold gasket?

Let's get it running right and then talk props.

 

[Joe Reeves]

Re: 1979 15 hp Evinrude

Your engine either has a fuel/air leak at some point between the fuel pump and the fuel supply OR the fuel pump is failing.

 

[Cornell]

Re: 1979 15 hp Evinrude

I agree with the advice to fix fuel problem first then go to the planning question. However, if you are stumped, a common sense approach is to see if a buddy has an outboard like yours and try it. I just bought a 15 hp Evinrude used, 1988. It has lots of power. Also about planning. I had a 7.5 hp Merc before on my 12' aluminum boat and it would fly with 160-200 lbs in the boat. But it took a while to get the nose down. I would almost have to lean forward and put the tackle box etc. up front. Then I installed a planning plate that I bought from Bass Pro. After that it jumped right up on plane. Does it rob you of power or speed? I don't know but will find out as I have a speedometer on the boat now. (of course all this is assuming that the motor angle to transom is correct) This was an easy install and not expensive.

 

[craigrs8271]

Re: 1979 15 hp Evinrude

Hey guys

Thanx for all the feedback!!! To answer a question ,It does have 2 coils. It ran rough when I first bought it ,I changed plugs etc... Still ran rough, I pulled the coil wires 1 by 1 & found one of them was not getting any spark, motor died.....
After checking to make sure all wires were connected good & checking to make sure the stop switch was not causing this ,(as they can) I figured it was the coil. Put another one on & STILL no spark out of it. I took it in for a diagnostics & thats what they come up with.
I put it on myself took it out & thats when I found out it would only run wide open with the choke full out.
I took it home & put a carb kit on as well as cleaned the fuel filter,new gas tank & hose..
Now it will only run wide open with choke 1/4 way out..

I did replace all gaskets they seemed to seal up fine.. I thought I had done a pretty clean & tight job when I did the carb. kit.

Is there any way besides just looking to check for an air leak that I maybe missing ??????

I thought about the fuel pump might having a small hole in the diaphram but was trying to check other things I might be missing first..

I bought this motor for $50 which I thought was a steal at the time. It looks good inside & out (not beat up at all,good paint)... I now have with everything I have done to it about $220 in this.. I just do not want to put more $ into this then what it is worth. With me putting another $60 for a fuel pump I will have $280 into this motor...

Hopefully that would take care of the problem if not I am left with putting more $ into this.
I have seen the same motor & Johnson 15 hp sell for $700 here where I am from.. Does that sound about right???? Is it worth dumping more for a fuel pump or is there other things I should check ????


Someone I have spoken to said something about jet adjustment ?????

Thank you
Craig

 

[Joe Reeves]

Re: 1979 15 hp Evinrude

(Carburetor Adjustment - Single S/S Adjustable Needle Valve)
(J. Reeves)

Initial setting is: Slow speed = seat gently, then open 1-1/2 turns.

Start engine and set the rpms to where it just stays running. In segments of 1/8 turns, start to turn the S/S needle valve in. Wait a few seconds for the engine to respond. As you turn the valve in, the rpms will increase. Lower the rpms again to where the engine will just stay running.

Eventually you'll hit the point where the engine wants to die out or it will spit back (sounds like a mild backfire). At that point, back out the valve 1/4 turn. Within that 1/4 turn, you'll find the smoothest slow speed setting.

Note: As a final double check setting of the slow speed valve(s), if the engine has more than one carburetor, do not attempt to gradually adjust all of the valves/carburetors at the same time. Do one at a time until you hit the above response (die out or spit back), then go on to the next valve/carburetor. It may be necessary to back out "all" of the slow speed adjustable needle valves 1/8 turn before doing this final adjustment due to the fact that one of the valves might be initially set ever so slightly lean.

When you have finished the above adjustment, you will have no reason to move them again unless the carburetor fouls/gums up from sitting, in which case you would be required to remove, clean, and rebuild the carburetor anyway.

When time permits, visit my store (copy/paste) at: stores.ebay.com/Evinrude-Johnson-Outboard-Parts-etc?refid=store

 

[wildmaninal]

Re: 1979 15 hp Evinrude

Have you done a compression check on that motor?

By some chance if what Joe Reeves said doesn't work replace the fuel pump after doing a compression check and that you see that the motor checks out good. This would give you an idea what kind of life the motor has had and might have left. It would also be good to know the compression that way if you wanted to check it again in the future you will have an idea of what kind of wear the motor has gone through compared to what it was.

You got a deal on that motor, I wished I could find them that cheap even with bad compression, take and sell it for parts and still make a profit.

 

[Cornell]

Re: 1979 15 hp Evinrude

Question; Is there any way besides just looking to check for an air leak that I maybe missing ??????
Craig. It has to be a lean main jet situation. Either too much air is getting in somehow at full throttle or your main jet is too small due to being gummed up. Did you take it out and clean it? Can you? Maybe carb cleaner and air pressure can help here. I just rebuilt my merc carb. Can't be too much different. I think it has to be a simple problem. Don't get discouraged. Gas combustion engines want 15 parts air to 1 part fuel in general. Give it to them and they will be happy. If you are getting performance with part choke you are just eliminating some air to bring it to the 15:1 ratio. So it isn't getting enough fuel. Simple approach. If it was me I would take off carb again and see if any of the gaskets didn't seat right. Tighten the manifold that carb attaches to to see if it is loose or cracked. Clean main jet if you didn't the 1st time. Make sure your fuel mix is correct. Most 15 hp owners like the 50:1 mixture. You will figure it out. Like my dad used to say; "If it has compression, spark and fuel in the correct ratio- it's got to run". Simple philosophy but he won a lot of races. Good luck.

 

[flabum]

Re: 1979 15 hp Evinrude

First isolate the problem. Run the engine again.... as the engine begins to die a full speed, pump the primer ball (without the choke on). If the engine regains, then you have either a bad fuel pump or an air leak or restriction between the tank and engine (make sure the vent on the tank is all the way open). If the engine does not regain, then the carb is at fault. It could still be clogged in the main jet.

 

[craigrs8271]

Re: 1979 15 hp Evinrude

Thanx again EVERYONE for the information. I will try to check all this again, this weekend weather permitting.
Thank You
Craig

 

[Kajun37]

Re: 1979 15 hp Evinrude

craig..those are some of the best lil motors out there..i have a 1979 evinrude 15hp also (15904E)...in 2000 i bought it for $360 and ran it for a couple yrs no probs...i moved and left it to my brother and he left it inside the boat and rain filled up the boat and swamped the motor.....i picked it up from him this summer and managed to get it unfroze and running, threw another $60-80 into it...brought it out and ran the heck out of it for 2 hrs....and then i started losing power...brought it home and did a compression check on it 30psi on top and 110 on bottom, wrist pin failure which scored the cylinder.....knowing how reliable this motor once was i am now going to rebuild it, gonna be my first full OB rebuild..prob cost me another $200+ but when its done it'll be like new and i'll have gained some more ob skills ....like you i see them go for 500-700+ on ebay all the time...you got a few more hundred to put into it before its not worth it.

check your compression and spark..spark must jump and 7/16th gap...then go from there...

 

[craigrs8271]

Re: 1979 15 hp Evinrude

Sorry I have not got back & let you know how it went.. The weather here has not been nice enough to do anything as well as me being down to a surgery.

I did try to take the boat out today. Before I left ,I fired the motor up. Fired right up!!!
I ran into a FRUSTRATING problem......The spring on the pull starter hung up so I took it apart. YES IT HAPPEND, A NIGHTMARE!!!The spring srung out on me & now for the life of me CAN NOT get the spring wound tight enough to get it back together with out springing it again.
Does anyone have an easy way of getting this back together????VERY VERY FRUSTRATING!!
Thanks
Craig

 

[HighTrim]

Re: 1979 15 hp Evinrude

Refer to this thread, it will help you. Just make sure you are wearing your safety glasses and gloves. May also want to put a cup on

http://forums.iboats.com/showthread.php?t=229651

 

[ezeke]

Re: 1979 15 hp Evinrude

The 13' Boston Whaler is usually rated 35 to 45 HP depending on the model. If you want to run it with a 15HP you need to use a lower pitch prop. The 387389 [now superseded by 763457] 9.25X8 would be better, but you could go lower.

 

[samo_ott]

Re: 1979 15 hp Evinrude

This sounds like a carb rebuild issue to me. But eliminate the pump first by pumping it when it falters but my bet is that you missed something in the carb and a 2nd more thorough cleaning should do it... Once you fix the pull start.

And $50? What a steal. I'd buy them everyday at that price if I could find em. Even if you couldn't get it running you could part it out and make $$$ on it! They go for $700-$1000 in my area.