Fuel Leaking From Power Head

[dblanton]

On a 81 75hp Evinrude I have fuel dripping from the lower portion of the power head when I kill the engine, is it supposed to do that as some kind of way to drain excess fuel from the crankcase when the engine is not running? Doesn’t seem to be a problem while the engine is running. I have checked all the fuel lines, carb's, intake gaskets etc but no sign of a leak. Engine runs great at idle and at WOT. The fuel drips from the bolt heads that attach the crankcase head assembly to the engine. I replaced the seal and the o-ring on the crankcase head assembly but that did not fix it and no sign of fuel leaking top side and running down.

[StianM]

Tru to hit the carb with a hamer or the head of a screw driver.

There is not suposed to be so mutch gasoline in the air fuel mix that it would leak anny from a gasket on the engine.

[Frosty]

Dont go hitting things with a hammer---please.

I think Stian feels that the carbs are flooding, it would not run well or at all if it was. I have a feeling you know this.

How long does it take for the fuel to show itself, or is it there the moment you open the engine cover.

[StianM]

Originally Posted by jack frost

Dont go hitting things with a hammer---please.

Maybe I should have spesefyed that this has to be just a light toutch.

It's defently the first thing I would do befour Investigating anny futher.

[Frosty]

Stian ,---the engine runs great at idle and WOT

I know you think a float is stuck but if that was the case it may start but run crap.

Lets just investigate where the fuel is coming from first.

[StianM]

Originally Posted by jack frost

Stian ,---the engine runs great at idle and WOT

I know you think a float is stuck but if that was the case it may start but run crap.

Lets just investigate where the fuel is coming from first.

The fuel is comming from the fuel thank

Engines are strange beings, I have heard about people running out off fuel has made old SABB diesels runn only by pooring lube oil into the airfilter.

A angine runnong perfectly with a floded carb would not suprise me even it's not normal.

How is the fuelpump fitted on this engine by the way?

[dblanton]

I cleaned all the leaking fuel so everything would be dry and clean; then I connected the fuel line and gave the bulb a few good pumps to fill the carbs with fuel and just let it set to see if fuel would leak. No sign of a leak after sitting for 1 hour with pressure on the primer bulb, then I turned the engine several times by hand and let it sit another 1 hour still no leaks. After that I started it up with the ear muffs on and let it idle for three minutes then shut it down and watched for a leak, with in 1 minute fuel began leaking from around the flange of the crankshaft bearing cap. This is the same place the leak was before. I have replaced the seal and the o-ring on the crankshaft bearing cap but that didn't stop the leak. So I have isolated where the leak is coming from but I don't have any idea as to how to fix it.

[Frosty]

Im still confused here the top bearing cap is way under the fly wheel.

The bottom bearing cap is way inside the engine block and only acessable with the engine of the leg.

So you've removed the engine and replaced these?

How much fuel are we talking about here.

[dblanton]

Yes I have removed the power head from the leg to get to the lower crankshaft bearing cap (some times referred to as the Crankcase Head Assy.) and replaced the seal and the O-ring which are the only sealing devices for the bearing cap. As far as the amount of fuel leaking I would estimate 1 ounce maybe slightly less before the leak stops which I assume is because all the fuel has leaked out.

[Frosty]

Thats my point how can you see that it is leaking from there when it is way inside the power head assy.

If fuel is leaking from the ring of bolts around the power head assy then that is not necessarily the bearing cap that is leaking.

below the power head is basically two sections, exhaust --where the bearing cap is and the shaft, and water jackets.

How can you see the bearing cap after the engine has been running.

[dblanton]

On this particular engine the lower bearing cap bolts to the block not on the inside of the block, there is enough space between the cowling of the engine and the transom mount to see the bottom of the block where the bearing cap bolts to the block. I can actually touch the bolt heads that mount the bearing cap to the block with my fingers with ease, which is why I am able to see the fuel seep out from around the flange of the bearing cap that the mounting bolts go through.

[dblanton]

I have attached a diagram that shows the bearing cap (#20) #19 is the O-ring and # 21 is the seal. Perhaps this will help clear up some of the confusion.

[Frosty]

Ok well in that case run the engine as you did before only this time run the carbs dry untill it stops. Then lets see if it leaks then.

[dblanton]

I have disconnected the fuel line and ran the carb's dry but the leak is still there. After a few minutes the leak stops but I feel that is because all of the fuel has leaked out.

[Frosty]

Is this an oil injection model or do you mix fuel with oil.