77 Evinrude 15HP dying after working fine, then idles, and works, and dies again.

[kstrickland1012]

So, I have a 77 Evinrude 15HP and it works fine every time I take it out and every time it will just cut of all of the way or go straight to idle anywhere from roughly 5 - 20 minutes into my trip. Sometimes I can't get it to go back in gear for a while and sometimes it goes fine again but will eventually die. I cleaned the carb and replaced the fuel. I am a helicopter mechanic with little experience on boats. I want to learn, have a manul and think I could fix whatever is wrong but I am kinda lost at this point. Thanks

 

[Rick.]

Re: 77 Evinrude 15HP dying after working fine, then idles, and works, and dies again.

Assuming you did a good job on the carb. I'm wondering if you are opening the vent on the tank. The fuel pump creates suction (negative pressure) in the tank so it needs to be able to suck air into the tank or eventually the pump can't suck anymore. Could be other stuff but lets start with the easy things first. Best of luck. Rick.

Edit: If your keen to learn here is a site that is packed full of good information on the 9.9 and 15's (they are almost identical) and a site that will show you a parts break down of your engine.
http://www.sschapterpsa.com/ramblings/OMC/OMC info.htm

http://shop2.evinrude.com/ext/index.aspx?s1=5887005b165661c6c5ab7ba925badfcf

 

[jay mendoza]

Re: 77 Evinrude 15HP dying after working fine, then idles, and works, and dies again.

Open the tank cap 1/4 turn so it's venting. Next, if it starts to die again, give the fuel bulb a squeeze or two and see if that makes it pick back up. On engines as old as yours, the pump diaphragms shrink and dry out making the pump output sporadic, especially at low RPMs. If it takes squeezing the fuel bulb to keep it running, get a fuel pump rebuild kit and overhaul the pump.

 

[kstrickland1012]

Re: 77 Evinrude 15HP dying after working fine, then idles, and works, and dies again.

Thank you guys so much for the quick response to my problem. I am pretty sure that I put the carb back together right. I cleaned the carb before having this problem and it was pretty easy. It ran fine for about a month since I did that and I think I am venting it. I turn the vent open enough to hear it hissing at me and then I stop. Should I open it more? Haven't tried pumping the bulb yet when it's dying on me, will do that next time. I took the fuel pump apart and I can't really tell if it's bad or not. I might just replace it to rule that out and with it being 30 years old, it couldn't hurt. I will reply with any new details and thanks again for your help.

 

[kstrickland1012]

Re: 77 Evinrude 15HP dying after working fine, then idles, and works, and dies again.

I took the fuel pump apart and couldn't find anything that looked wrong with it other than the diaphram appeared to be suctioned to the housing. I put it all together and pumped the bulb to make sure fuel flowed freely through output hose and it did. I took my boat back out on the water, vented the cap properly and the same thing would happen, then I pumped the bulb when it would start to die after giving it more throttle, nothing changed. It still surges and won't give me any power. Doesn't this sound like a fuel flow problem? I think I may need to take another look at the carb. Am I on the right track with troubleshooting or is this a sign of something else??:confused

 

[Rick.]

Re: 77 Evinrude 15HP dying after working fine, then idles, and works, and dies again.

I just can't picture myself giving a helicopter mechanic any advice. LOL. Anyway your right, it does sound like you could be having fuel problems so I would give the carb. anoter good cleaning. It is also recommended to repalce your fuel lines form tank to carb. due to methanol fuel issues degrading the rubber. Free floating rubber can foul a clean carb. in a matter of seconds. Have you checked for good spark? It needs to jump a 3/8 inch gap with a snappy blue/white color. Check the FAQ for how to set your slow speed needle when completed. Keep trying you have a good motor and once it is running right you will enjoy it very much. Rick.

 

[iwombat]

Re: 77 Evinrude 15HP dying after working fine, then idles, and works, and dies again.

Surging did you say? That's usually indicative of a cylinder cutting in and out. If you haven't done it already, the standard spark check and compression test are in order.

How long after it cuts out can you start it again. Long enough for the ignition components to cool down?

 

[kstrickland1012]

Re: 77 Evinrude 15HP dying after working fine, then idles, and works, and dies again.

I can turn it back on instantly, but after about running an additional 10 minutes or so while it's surging, it will kick in back to normal and then die again, going back into surge mode. It has been a reliable motor, much faster than paddling at least, but I know it has great potential and I need to get her further than a mile away so running better is a must. Think I need new spark plugs and fuel lines?? Or just verify the gap??

 

[bktheking]

Re: 77 Evinrude 15HP dying after working fine, then idles, and works, and dies again.

How do the coils look, visually inspect for cracks. Check plugs as well. Plugs are cheap, replace if suspect.

 

[henrye718]

Re: 77 Evinrude 15HP dying after working fine, then idles, and works, and dies again.

when it happens pick your gas tank up and flip it and shake it around sounds like there is crap in your tank or lines. CLOSE THE VENTS AND CAP FIRST!

 

[kstrickland1012]

Re: 77 Evinrude 15HP dying after working fine, then idles, and works, and dies again.

I removed the spark plugs and they look pretty bad. I verified the gap and it's supposed to be .040 and it was .030 for both. I also took the carb out again and the float looks dirty and doesn't swing freely. I just replaced the plastic thingy with a small nail and bent it over, swings much better now. I am going to replace with a carb kit and most likely get new plugs also. I pumped fuel through the lines and it came out, so should I replace them still? I will shake the tank to get rid of the possability of that being the problem. Thanks for all of the replies and I will keep you posted with how it goes.

 

[Rick.]

Re: 77 Evinrude 15HP dying after working fine, then idles, and works, and dies again.

Actually the plug gap is .030 for your engine, although I'm sure it will run fine at .040. The fuel lines are up to you but it is a good idea. Shaking the tank is just going to stir up a bunch of contamination if it is in there. I would suggest removing the suction line from inside the tank and seeing if your screen is plugged if it is a metal tank. Not quite sure how if it is plastic but if plastic there won't be any corrosion anyway. Glad to hear your making progress. Rick.

 

[kstrickland1012]

Re: 77 Evinrude 15HP dying after working fine, then idles, and works, and dies again.

After pulling the carb out again I noticed a black piece of rubber or something caught in the main jet. I cleaned it out real good and then put it all back together. I took it out yesterday and it runs like a champ. I think I will replace lines fo sho. Also ordering a carb kit and new plugs just to have peace of mind. The book I have says .040 gap but I have noticed hesitation with starting now, so I will fix that. Thank you everyone that has helped me out.

 

[kbait]

Re: 77 Evinrude 15HP dying after working fine, then idles, and works, and dies again.

Remember to flush fuel through before you hook up the carb after you change lines in case there's still something in the pump, or connector. I'm sure gap is .030. If available, use non -oxygenated (non ethanol) fuel. You have a great motor! (mine's a '75, and I LOVE it!)

 

[Rick.]

Re: 77 Evinrude 15HP dying after working fine, then idles, and works, and dies again.

Glad to hear your up and running. I hope you get lots of enjoyment/use out of it. they do seem to last forever. Rick.