1975 Evinrude 115hp carb clean

Joined
Aug 21, 2012
Messages
7
Hey guys,

Once again looking to you for friendly advise. Had numerous small problems with our 1975 Steury TriHull... Fixed everything easy; new control cables, new battery, new plugs... We are having a cold start issue... just cranks does not even stumble. After cranking and cranking, by hand, pulling plugs to prevent flooding, it just comes to life....

(I hate the my car is broken, it just doesn't feel right; Im a service manager for a car dealership. What, Why, how, etc)The only "Evidence" I have other then a long time to start cold, fires right up within 2 hours of previously running. When we are attempting to start it we notice fuel dripping out from under the air intake/carb, when attempting to start, will get a nice little puddle under it. We spray it out, and it does not leak when just sitting or running, only when cranking.

Boat Co-Owner and I have put our heads together and think maybe a carb cleaning....

So big question, If we buy the carb cleaning kit with gaskets and what not, do we need to do an overhaul? or is it literally just pull it apart, clean, and put it back.... without any crazy adjustments or syncing or anything?


Hoping it's pretty easy, He's a mechanic and I'm a service manager. Very mechanically inclined.
 

Bosunsmate

Admiral
Joined
Apr 7, 2012
Messages
6,129
Re: 1975 Evinrude 115hp carb clean

Does the primer bulb hold firm with engine off?
No nothings crazy about putting it back together, just like a car, put back what you undo!
 

boobie

Supreme Mariner
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Nov 5, 2009
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20,826
Re: 1975 Evinrude 115hp carb clean

Well you being a service manager and him a mechanic should both know how important it is to have an OEM factory service manual. You can get them here on I-Boats. All the specs and how to's are in them. With every vehicle I've ever owned I always got a factory manual.
 
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Bob_VT

Moderator & Unofficial iBoats Historian
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May 19, 2001
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26,019
Re: 1975 Evinrude 115hp carb clean

Get some carb cleaner and do one carb at a time. It is basically take them apart, make them spotless, use air to make sure all the tiny passages are clean, re-assemble and carefully set and check the floats.......then do the second carb.

I have big hands and some of the nuts are a PITA because you have to remove them as the carb is being moved. You will see ;)

Pull both carbs at once and install the same way do not mix up the top and bottom carb. Take pictures of the linkages to help them go back together.
 
Joined
Aug 21, 2012
Messages
7
Re: 1975 Evinrude 115hp carb clean

We definitely plan on purchasing a factory service manual, on this site it was about 60 bucks. We plan on a major overhaul in the future... We're more concerned with getting in over our heads before it arrives and the boat not being on the water. We got out twice a week. After cranking on ear muffs for about 10-15 minutes and avoiding flooding we warm it up and its fine on the water. If we try to start in the water it has taken an hour. The primer bulb holds nice and firm with the engine off, we do have to reprime after about two hours off though... not sure how long it should hold firm though. I personally use the clean piece of cardboard laid out and use a sharpie to label/diagram
 

boobie

Supreme Mariner
Joined
Nov 5, 2009
Messages
20,826
Re: 1975 Evinrude 115hp carb clean

Check your compression first and then the spark. Spark should jump a 7/16" open air gap on a tester.
 
Joined
Aug 21, 2012
Messages
7
Re: 1975 Evinrude 115hp carb clean

Thanks much guys! Your feedback, knowledge, and advice is always appreciated.
 
Joined
Aug 21, 2012
Messages
7
Re: 1975 Evinrude 115hp carb clean

UPDATE:

So took everything apart, went very smooth, and yes Bob_Vt a handful of PITA bolts for sure.

The unexpected results... We found the carbs were VERY recently cleaned and rebuilt. I did find a loose fuel line on the bottom carb that was actively leaking (Loose zip tie). On the bottom carb we found the needle valve stuck closed. looked as if when the previous owner installed it he pressed VERY hard down on it and it actually ended up having a large indentation around the tip.

Theory is... We've only ever been running on two of the four cylinders because the fuel needle valve was stuck closed and a fuel line leak.... explains the extremely low gas mileage and the extremely long cold starts.

I had a carb clean kit from a johnson I had in the past and the valve seats and needle valves were identical and brand new. We replaced them and reinstalled everything.

We had a (brief) moment of panic when we thought we had a run away throttle. It started almost instantly and the RPMs sounded crazy high! Took about 1 second to realize.... Oh this is what is is supposed to REALLY sound like on all four cylinders.


We'll be taking it on the water tomorrow and will let you guys know about performance and gas consumption.


THANK YOU GUYS AGAIN FOR YOUR ADVICE AND INFORMATION!!!!
 

emdsapmgr

Supreme Mariner
Joined
Dec 9, 2005
Messages
11,551
Re: 1975 Evinrude 115hp carb clean

When the engine was only running on the top carb, that means the bottom two cyls were deprived of both fuel and oil. Hope the two bottom cyls did not get damaged from no lubrication while running... you may want to have a look inside the spark plug holes of the two bottom cyls.
 
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