'93 Evinrude 4 hp

I took my boat out yesterday and I noticed 3 things after I ran my motor for a while:

1. When I kept the motor at a constant throttle position I noticed that the power went in and out some (strong for a couple of seconds and weak for a couple).

2. I just bought a brand new fuel line after I thought something was wrong with my other and I notice that the hand ball on the line does not stay stiff. Should it stay stiff the whole time I run the motor?

3. The motor will also cut out some. I ran it for about 20 minutes yesterday and it cut out at least 2 times going from half throttle to cutting off. It started back up with about 5-10 pulls but it was aggravating with it cutting off like it did.

Any thoughts on what I need to to to look into this futher or fix it?

i just picked up a simular motor.
the primer should stay stiff once the motor is primed. when the motor is dieing try pumping the primer to see if that helps. if it does, its probably the fuel pump.

check the fuel pump by pulling the fuel line off the carb while the motor is running. fuel should pulse out. mine had low output but would run fine at anythning under full throttle. there is a rebuild kit available for $20. unfortunatly it does not come with the valve plate that i needed so i had to buy a new pump.($100) you should be able to blow into the pump from the fuel side and not from the carb side. if it doesnt pass this test then the pump is bad.

mine also had an intermitent spark problem on one cylender. you can check this by hooking up an inductive timming light the the spark plug leads while the engine is acting up. chances are its one of the coils. mine would short the #1 cylender coil once warmed up. set your points at .020. better yet replace them and the condencers. its only $20 for the set.

engine compression should be around 100psi, but it will still run with 60.

post a follow-up.---tom

nashua,

So in order, I should:

1. Check the fuel pump bu cranking it and pull the fuel line from the carb once started and I should look to see if fuel pulses out. How do I know if I have enough pulse? Should it shoot out with the strength that could take it several feet or should it kinda just ooze out?

2. I should then blow into the carb side of the line and make sure I cannot get any air in. How do I know if I just need a rebuild kit vs. a new pump?

3. Lastly I should check the coild by using an inductive timeing light. Where do I get this?

4. Do I need to check the compression also?

1. not sure, but should see something comming out. more than a trickle.

2. if you can blow in from the carb side chances are the valve plate is bad. you can take it apart and check all the rubber diaphram gaskets. pay special attention to the oreintation of all the parts. one mistake and it wont work. on the vlave plate there are two check valves. you should be able to blow through each one only one way. if the valve plate is good then all you probably need is the rebuild kit.

Before disassembly, draw out arrows on your unit indicating UP when the unit is mounted on the motor. Also draw in the position of the fuel pump inlet fitting (A), the outlet fitting (B) and the assembly screws (C), relative to the wide valve body tab (D). Note some early units do not have this moulded in body tab. This sketch will later be used to reassemble the pump correctly.

memorize and beleive this before you even think about removing the fuel pump from the motor!!!

https://www.sschapterpsa.com/ramblings/Rebuilding_fuelpump.htm

3.you can borrow a timming light from most chain autoparts stores(autozone, advanced auto) you will need a battery to power most of them but i have seen self powered ones. when the engine acts up clamp it onto one of the sparkplug leads. you should see a steady flash. check both leads. if you dont see a steady flash there is a problem with the ignition system somewhere.

4. you can also borrow the compression checker. remove both plugs and set the throttle to wide open. crank the motor over by hand with the pull start until you get the highest reading on the gauge.

tests one and three should be done with the engine mounted in a barel of water. never run the engine without the lower unit submerged in water.

post the results of your tests.

nashua,

I just talked to someone else that said that the primer ball on the fuel line should be stiff at first before the motor is fired but once you are underway, the ball should not remain stiff. Are you pretty confident that it should stay stiff all the while motoring?

thank you for your time,

The primer bulb should only feel pressurized when you first prime the fuel system. Once the engine is running the bulb is on the suction side of the fuel pump and there is no way it can remain pressurized.
As far as your running issues are concerned. Try the primer bulb when the issues occur , or try a squeeze bottle with fuel/oil in it and squirt some down the carb throat when the issue occurs. If the bulb cures it then look at rebuilding the pump. If the squeeze bottle changes it for the better you will need a good carb cleaning and a kit.

The primer bulb should only feel pressurized when you first prime the fuel system. Once the engine is running the bulb is on the suction side of the fuel pump and there is no way it can remain pressurized.

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my bad.

the power up/down is usually associated with the float moving up/down in the bowl. take it apart and check the float very closely as you move it up/down w/ your finger. blow threw the fuel line to see at what point it opens and closes. check the needle backings and clean all the jets

any follow up on this?

i just gps'ed mine yesterday and i can hit 14mph with just me in my 12' semi boat. mines running good!