'77 35hp Evinrude; will only run at 1/4 power, dies at power up

[Jggrmson]

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Ok...here is the deal, received a 16' jon boat with a 35hp electric start outboard from my parents who...are getting to old to fish. they bought it 5 years before i got it and let it sit in the back yard for 4 of those years with gas in the tank, lines and carb.

here is what it is doing.
1st got it, wouldn't start at all. cleaned the carb, started ran rough, coughed and died. after running it on the lake 1/4 throttle for an hour or so it worked out the dust and ran "OK" except when i put the throttle past a quarter power. i later discovered that if...when i pushed the throttle past the 1/4th mark...just when it was about to die, i pulled the choke (close) it would recover and give me 1/2 power (throttle) unless i power down to 1/4 which it will die unless i open the choke again. whhheeewwww **panting**

here is what i have done since then.
Cleaned the carb again. it was still very clean from before. used 4 can of carb cleaner, pulled the bowl off, sprayed in the jets and came out clean. used compressor to blow the ^^^^ out of it. basically cleaned it for hours and feel confident about it.
replaced the gas tank fuel line from tank to motor, rebuilt fuel pump/filter. replaced all gaskets from block to air box. inspected all fuel lines within the motor. cleaned it a lot.

the motor starts and runs great in the yard with the 'ears' on it. runs good in the water at idle and slightly above idle speeds. as soon as you power up...cough, cough. same stuff.

my pride has been pricked and i really don't want to take it to the shop.

 

[tashasdaddy]

Re: '77 35hp Evinrude issues

Re: '77 35hp Evinrude issues

you have to start at the beginning of trouble shooting. compression check all cylinders, spark check all cylinders.

good reading here. http://forums.iboats.com/showthread.php?t=299680

buy an OEM Service manual, if you are going to work on it yourself. http://www.outboardbooks.com/

 

[Jggrmson]

Re: '77 35hp Evinrude; will only run at 1/4 power, dies at power up

spark is strong on both cylinders. Have not checked compression yet. but will this weekend. The motor ran great before it was allowed to sit...so i assume the compression is good. will check any way. Thanks S/F

 

[17bowrider]

Re: '77 35hp Evinrude; will only run at 1/4 power, dies at power up

still sounds like theres dirt in the carbs ive had same problem with an old johnson 50 one time came to the point were i almost gave up then i soacked them in brake disk cleaner over night and blew out with air compressor and boom no more problems?

 

[Jggrmson]

Re: '77 35hp Evinrude; will only run at 1/4 power, dies at power up

I knew someone, if not everyone, would say that. Iv soaked it twice. sprayed it out with brake and carb aerosol for literally hours and hit it with the air compressor twice. the only thing i have not done is pull the jet/s. im worried about breaking it. i may order a new one and just take it out with channel locks and replace it...thanks S/F

 

[Jggrmson]

Re: '77 35hp Evinrude; will only run at 1/4 power, dies at power up

* update*

ok i checked the compression with an OEM engine compression gauge that I rented from autozone. read 34-35psi on the upper and 35-36 psi on the lower. seemed really low to me but I don't know what it should be at. Tried it again the next day with the engine warm both at idle throttle and WOT. same results.
this was the first time i have started it since i cleaned the fuel pump/filter and the carb (third time) three days ago. started right up on the first turn. still kinda has a slight miss at certain throttle points. i ordered a new needle and seat which i will replace when it comes in. should i go ahead and get the whole carb kit, jets etc?

with only one reply im kinda getting bummed...somebody tell me somthing

 

[Will Bark]

Re: '77 35hp Evinrude; will only run at 1/4 power, dies at power up

Compression is really low but at least it is almost equal; Have you done the de-carb which is described up in the secret files section? This may help you out since the carb must be clean after all of the work on it. de-carb can't do anything but help; just be prepared for a lot of smoke.

 

[Jggrmson]

Re: '77 35hp Evinrude; will only run at 1/4 power, dies at power up

Haven't decarbed it. If I run a gallon of gas through the public lake i use smoking like you say it will...it wont be good.

Can i just run some seafoam through the carb while it is running in the yard? Wont get WOT but better than nothing right?

I just ordered the carb rebuild kit with floater, needle and seat from this site. will soak the carb from now until it gets here, then rebuild it Wednesday with fingers crossed.

 

[tnurgeniram]

Re: '77 35hp Evinrude; will only run at 1/4 power, dies at power up

My 30hp Evinrude was recently doing something similar...

Check the return line at that comes out the bottom of the float bowl on the carb. If this line is kinked or blocked it will cause your engine to flood.

Anyway, your problem sounds similar to mine. A couple of re-routed fuel lines and she purred like a kitten. Hope this helps!

 

[Will Bark]

Re: '77 35hp Evinrude; will only run at 1/4 power, dies at power up

Same here; my lake would have gone nuts if I did that. So I did a gallon milk jug with 3/4 can of seafoam and 3 ozs of oil running on the muffs. No gnats or mosquitos for a week but it did its job. Just don't go WOT or you could scatter motor parts all over the yard. Ran 1/2 gallon and then shut down for 15 minutes and then finshed the the other half.

 

[Jggrmson]

Re: '77 35hp Evinrude; will only run at 1/4 power, dies at power up

rebuilt the carb this evening and put everything back together...wouldnt start. put some carb cleaner down her throat and she fired for a sec and died again. Must have put something back together wrong. VERY DISCOURAGING. i did find that the little, tiny wire/spring that attaches to the needle from the float to open and close the float valve was missing. could this have caused all of my problems? hope that i find the issue tomorrow and can test run her. S/F

 

[F_R]

Re: '77 35hp Evinrude; will only run at 1/4 power, dies at power up

Absolutely, that clip has to be in there. I haven't read through this entire thread, but have you checked the high speed jet in the bottom of the carburetor bowl? It sounds like it may be dirty. It must be absolutely clean without a trace of any dirt or varnish in it.

 

[jasper60103]

Re: '77 35hp Evinrude; will only run at 1/4 power, dies at power up

Regarding your compression. I will say I don't trust the gauges at my local Autozone. Two reported low readings, but I borrowed one from O'Reilly Auto parts and the compression reading was fine.

 

[Jggrmson]

Re: '77 35hp Evinrude; will only run at 1/4 power, dies at power up

got up this morning (its my Saturday) and started the motor....ran very rough, lots of smoke, and some kind of oil/sludge came out of the exhaust. how bad is that? I could only keep it running by playing with the throttle. it hasn't ran this rough since i got it.

 

[tnurgeniram]

Re: '77 35hp Evinrude; will only run at 1/4 power, dies at power up

got up this morning (its my Saturday) and started the motor....ran very rough, lots of smoke, and some kind of oil/sludge came out of the exhaust. how bad is that? I could only keep it running by playing with the throttle. it hasn't ran this rough since i got it.

What fuel mixture are you using? If you are running rich (too much oil), the unused oil can/will run out of the exhaust. Does the "oil/sludge" smell like fuel? If so, double check what your fuel mixture is and what is should be. Probably should be around 50:1.

 

[Jggrmson]

Re: '77 35hp Evinrude; will only run at 1/4 power, dies at power up

I'm pretty sure the issue is that it is flooding. when i try to start it at wot it will start until i power down. there is fuel coming out of the front of the carb after a few failed starts. plugs are wet with fuel. dry em off, small shot of carb cleaner down the throat then, WOT then it will start.

 

[jasper60103]

Re: '77 35hp Evinrude; will only run at 1/4 power, dies at power up

rebuilt the carb this evening and put everything back together...wouldnt start. put some carb cleaner down her throat and she fired for a sec and died again. Must have put something back together wrong. VERY DISCOURAGING. i did find that the little, tiny wire/spring that attaches to the needle from the float to open and close the float valve was missing. could this have caused all of my problems? hope that i find the issue tomorrow and can test run her. S/F

Did you get the float valve setup right? That would definitely allow too much fuel in the carb

 

[Jggrmson]

Re: '77 35hp Evinrude; will only run at 1/4 power, dies at power up

Did you get the float valve setup right? That would definitely allow too much fuel in the carb

I installed it exactly as it was removed. I put a new valve and seat in it with the little wire spring thingy as described. when the float goes up it fully closes the valve and when it goes down it open it. it that it? it there some kind of setting i should check? I'm....just about to give up and use it to shoot at....im serious.

 

[jasper60103]

Re: '77 35hp Evinrude; will only run at 1/4 power, dies at power up

I installed it exactly as it was removed. I put a new valve and seat in it with the little wire spring thingy as described. when the float goes up it fully closes the valve and when it goes down it open it. it that it? it there some kind of setting i should check? I'm....just about to give up and use it to shoot at....im serious.

That's pretty much how it functions. Most will do a blow test after the carb assembly to ensure the float valve is opening and closing as it should. Attach a hose to the carb. With the carb right side up, you should be able to blow throw it. With it upside down, you should NOT be able to.

But before you assemble the carb, there are a couple adjustments to make, float level and float drop.

With the carb upside down the float should be parallel with the gasket surface. Also, when the carb is right up, the float edge should be a certain distance from the gasket surface, e.g. 1" for my carb.

edit: Get yourself a spray bottle with fuel mix for troubleshooting, not carb spray. Also, see the Top Secret Files for Carb adjustments and other tips.
http://forums.iboats.com/showthread.php?t=299680

See pics below.

 

[Jggrmson]

Re: '77 35hp Evinrude; will only run at 1/4 power, dies at power up

ok....very helpful. adjusted the float and blow tested it. FAIL! took off the sping/wire/thing and it fired right up. some minor slow speed screw adjustments and its idling on the muffs right now; sounds like victory. added 3/4th bottle of Seafoam to the last gallon of gas/oil in the tank. when it runs through that i will take it to the lake for a test run. still dont know if the initial problem (past 1/4 throttle) is fixed. we'll see. Thank you