Evinrude V4 115hp 1985 question

M

marialeon305

Recruit
Joined
Aug 30, 2010
Messages
4
I have an 1985 Evinrude V4 115hp that is giving us problems. It runs great at idle but when we speed up it starts slowing down then it speeds up and slows down. Does not keep the speed. What can be the problem?
We had the carb, spark plugs,everything checked out and just last week even replaced the fuel pump. Does anyone know what the problem can be?
 
E

ezeke

Supreme Mariner
Joined
Sep 19, 2003
Messages
12,532
Re: Evinrude V4 115hp 1985 question

Surging is often caused by air leaks in the fuel system. A fuel obstruction or sticking float needles could also cause some variation of your symptoms.

What were your compression readings?
 
M

marialeon305

Recruit
Joined
Aug 30, 2010
Messages
4
Re: Evinrude V4 115hp 1985 question

thanks Ezeke the compresions were between 96 & 100 if I recall correctly. We do not know what else to do. Do you know where I can locate the float needles? Is that the needles in the carbs? I even had the carbs completed cleaned. The only thing we have not done is put in a water separator. Could that be a problem? My gas tank is only 25 gallons.
 
E

ezeke

Supreme Mariner
Joined
Sep 19, 2003
Messages
12,532
Re: Evinrude V4 115hp 1985 question

Water could be a problem; try running on a portable tank with new fuel and a different fuel line and bulb. Also flush the float bowls on your carburetors by removing the drain plugs one at a time and squeezing the primer bulb.

The float valve needles are in the carburetors; see the diagrams for your engine here: http://shop.evinrude.com/

In the meantime, put a little pressure on your primer bulb and look for leaks anywhere between the bulb and the engine, and correct any that you find; where fuel leaks out, air can and will get in.
 
E

emdsapmgr

Supreme Mariner
Joined
Dec 9, 2005
Messages
11,551
Re: Evinrude V4 115hp 1985 question

Try constantly priming the fuel hose primer bulb. This will force extra fuel into the carbs. If the engine runs fine, you may have a weak fuel pump.
 
M

marialeon305

Recruit
Joined
Aug 30, 2010
Messages
4
Re: Evinrude V4 115hp 1985 question

I already replaced the fuel pump and they engines still did the same thing.
 
E

emdsapmgr

Supreme Mariner
Joined
Dec 9, 2005
Messages
11,551
Re: Evinrude V4 115hp 1985 question

Possible fuel restriction. Try running it on a temporary tank-a 6 gallon type with it's own fuel hose.
 
Auxlarry

Auxlarry

Petty Officer 1st Class
Joined
May 21, 2010
Messages
304
Re: Evinrude V4 115hp 1985 question

Had the exact problem with my '85 115hp OMC and went through the entire fuel system. Pulled and cleaned the tank, replaced all hoses, fuel pump and pulled and rebuilt the carbs (Sierra kits) and still had the same issue.
Ezeke convinced me it was still a fuel/carb problem so I pulled the carbs off again and rebuilt them with OEM rebuild kits. Don't know why but this fixed my problem!
Have put over 200 hours on the motor in the past four months and it has run flawlessly!
 
M

marialeon305

Recruit
Joined
Aug 30, 2010
Messages
4
Re: Evinrude V4 115hp 1985 question

After trying several things and not resolving the issue we decided to have it diagnosed at a shop. The diagnosis was that carb. # 2 was starving for fuel. We have now pulled out both
carbs and we ordered the carb. rebuild kit for both. We placed both carbs. in carb cleaner and aired out. Waiting to receive both kits to then put back together and test in the water
this weeked. Hoping this is going to solve the issue.
 
You must log in or register to reply here.
Top