gas leak at full tilt.

[Yesterday]

I was out on the weekend and had to beach momentarily. The water was very shallow so I ran the tilt on my Merc 850 up full. I have no limit switch and I'm not sure if that's supposed to limit upward or downward tilt? At any rate after a few minutes there was gas leaking from the power head, presumably from one or both of the carbs. Should the float/intake valves open enough to allow fuel to flow through the carbs just because it's at full tilt? Or should I be taking these back apart again to see what's up? They did look spotless & clean not long ago.

Extra notes:
She is a tad nasty on fuel, though I don't have a frame of reference for an 850.
She likes the "cold start lever" engaged some when even warm starting, leading me to believe there may be too much fuel in the system?
The engine runs well but sounds like it may be missing a bit at low to middle range speeds.
Compression is good, and any visible rotted/cracked wiring has been replaced.

Appreciate any input.

 

[mercurymang]

Re: gas leak at full tilt.

Both motors I have experience with do that when fully trimmed up.

 

[Yesterday]

Re: gas leak at full tilt.

Both motors I have experience with do that when fully trimmed up.

You'd think that would be a relief, but it's actually not. Something is still off with my setup. I know it's under prop'd but I can't see getting another 10 MPH out of it that way, and that's where it should be. Hmmmmmmm

 

[mercurymang]

Re: gas leak at full tilt.

By fixing the hook, do you mean to fiberglassed it?

 

[Yesterday]

Re: gas leak at full tilt.

By fixing the hook, do you mean to fiberglassed it?

Pulled it out as much as possible, then fiberglassed & filled, yep. I killed that part of the post because I messed up the numbers. It seems the calc still leaves me 6 MPH short with the 40 and 10 MPH with the 85, so I may still have some hull issues & playing around to do, but those numbers seem more right.

Fuel consumption on the other hand... I wish I could quantify it to gauge, but it seems a bit ridiculous.
With fairly heavy throttle (25-35 MPH), I can chew up a gallon in about 15/20 minutes. The boat is very light. (~1200 lbs = boat + motor = tilt + gas + battery + me + 40 LB of misc stuff)

 

[mercurymang]

Re: gas leak at full tilt.

Impressive Yesterday. How long did it take you to do that?

On another note, I'm willing to bet that mine uses the same amount of gas.

 

[Yesterday]

Re: gas leak at full tilt.

Impressive Yesterday. How long did it take you to do that?

On another note, I'm willing to bet that mine uses the same amount of gas.

Looks like about a month in my free time, though it was my "quiet season" at work:
http://forums.iboats.com/boat-restoration-building-hull-repair/hull-hook-repair-601888.html

But my boat factory specs @ 610 LBS, so it's about 1/3rd the weight of yours. Should be better on fuel than that I would think???

 

[merc850]

Re: gas leak at full tilt.

The limit switch is set to keep the motor from leaving the water while on plane, the middle button on the control (out) is hooked to it and when running slowly or beaching you have to press the UP + TRAILER buttons together.
Do you have a Tach? it helps you know where you are rpm wise when propping or running.
You can trim the motor out until the boat rides on the last couple of feet of the hull for more speed and fuel savings also the motor can be shimmed up on the transom for more performance ( the large plate over the prop should be close to the surface of the water).
Can't help with the fuel leakage problem but it shouldn't occur with the motor tilted up prop still in water.
Try pushing the throttle to full to plane then slowly back it off to slower cruising speed, this should save fuel.