25hp Evinrude Surging on top end

[scott_parker82]

I recently bought a 1990 25 hp evinrude w/electric start. It hadn't been started in about a year. I took it out and it started up just fine...idled good w/small miss. Opened it up and it would run great for about 10-15 seconds before it would start surging. Any ideas?<br /><br />Year: 1991<br />HP: 25<br />Mod No: E25TEEIE<br />Serial No: R 08623460

 

[fireman57]

Re: 25hp Evinrude Surging on top end

It could be a couple of things. You might have your high end carb jet partially clogged. The other thing might be a bad powerpack. Does it just lose rpms but keep running? When it it loses it's power and starts surging does it ever get it's power back? I would check for spark when it surges and then check the carb. Oh, one more thing -- does your fuel bulb go flat or lose pressure when it surges? Make sure that your tank is vented.

 

[Paul Moir]

Re: 25hp Evinrude Surging on top end

Fuel line air leaks, poor fuel pump performance, and fuel supply restrictions can pretty well all be ruled out by squeezing the primer bulb at full throttle and noting if that improves matters. Try it out to narrow your focus.

 

[dolluper]

Re: 25hp Evinrude Surging on top end

surging is caused by two things an air leak[fuel leak] or overheating hows the pee'er working good steady stream

 

[scott_parker82]

Re: 25hp Evinrude Surging on top end

fireman57, it just looses rpms but stays running. When it starts surging it won't re-gain rpms until you let off slightly and then gradually get it back up on top end....then repeats process. Vent was open on old metal tank. I replaced tank with plastic and new hose from tank to motor.<br /><br />dolluper, motor's not peeing....what should I check?

 

[Walker]

Re: 25hp Evinrude Surging on top end

This may be a long process to solve. Since the motor hasn't been run in a year I suggest a thorought carb cleaning and overhaul, new water pump, new plugs, fresh fuel, fuel pump test, and check all fuel lines. Since we can't hear what you are calling "surging" its gonna be hard to correctly diagnose to problem. Last motor I had that surged was caused by bad ground between the crankshaft and the flywheel. Good luck.

 

[fireman57]

Re: 25hp Evinrude Surging on top end

If it drops back to very low rpm's I would still suspect a weak powerpack. Check your connections and clean them up good. Also make sure that the plug wire has not turned and is seated good on the plug. I know this sounds basic but it happens. When it drops back to low rpms have a buddy use insulated pliers and pull a plug wire if it dies then you know that cylinder is working. Start it again and when it loses rpm's pull the other one. If there is no change then I would change that powerpack. If the packs are fine I would pull my carb and make sure the high speed jet is not clogged. I agree with dolluper and Paul that it could be a fuel problem I would make sure it's not a spark problem first. If you do take your carb apart go ahead and put a kit in it. Make sure that your float is not sticking.

 

[scott_parker82]

Re: 25hp Evinrude Surging on top end

Ok, I'll do some checking after work and see what I can do. Thanks for the input fellas.

 

[dolluper]

Re: 25hp Evinrude Surging on top end

after a long sit [year] the impeller in the water pump loses shape on fins and pumping becomes weak or nothing you said it wasn't pee'ing was any signs of water coming out or spitting from the exhaust

 

[scott_parker82]

Re: 25hp Evinrude Surging on top end

dolluper, water was spitting out of exhaust.

 

[dolluper]

Re: 25hp Evinrude Surging on top end

ok the pump is working [how good?] try what Paul told you to do and let us know

 

[scott_parker82]

Re: 25hp Evinrude Surging on top end

dolluper, the motor's not peeing now....what should I check?

 

[dolluper]

Re: 25hp Evinrude Surging on top end

no spitting from the exhaust ,then your going to have to drop the lower end off and inspect the pump if the impeller fins are missed shaped replace it 10 bucks or so ,check housing where impeller sits [the walls]for marks or grooves if you have a manual it is a pretty simple procedure so grab one down the road it will pay for itself ebay or dealers omc shop manuals are the best

 

[scott_parker82]

Re: 25hp Evinrude Surging on top end

Ok, got the impeller inspected and changed. Old one had some rubber shavings clogging the hole. Will the motor pee good with a cheap motor flusher (ie. suction cup with one side that produces water from garden hose) or should I try something else. Also took hose that water should come out of and blew threw it and felt good airflow from the end of pipe in lower end. Anything else I should check?

 

[dolluper]

Re: 25hp Evinrude Surging on top end

It,s all together put it in the water and try it out see if she,s working good now

 

[scott_parker82]

Re: 25hp Evinrude Surging on top end

Should I put it in the water to make sure or will the motor flusher work?

 

[Walker]

Re: 25hp Evinrude Surging on top end

Scott, the flusher will only tell you if anything is clogged up, and if you have the water tube installed in the top of the water pump, as the flusher supplies its own pressure. A trash can or barrel will work if you can't put her in the water. make sure the water level is above the waterpump. You know where it sits now that you've had it apart. Make sure the pisser hose isn't clogged up.

 

[scott_parker82]

Re: 25hp Evinrude Surging on top end

Thanks, will check it in the morning.

 

[scott_parker82]

Re: 25hp Evinrude Surging on top end

Ok, ran motor in a barrel this morning and no pee. I took the lower unit off and got in to the impeller area. The impeller was stuck. I lightly greased the impeller and put all back together and ran. It took about a min before it started peeing but it started. It would pee good for a min then would spit a bit. Should I just go ahead and change the whole thing?

 

[dolluper]

Re: 25hp Evinrude Surging on top end

sounds like a good idea as the grease did the pumping or clogging a new impeller whould probably do wonders