1988 Mariner 50 fuel delivery problem?

[RayGottsleben]

Boat has been laid up 3 winters. Was initially hard to start and often would not restart after stalling or turning off. Also, at above 5500 RPM, seems to starve for fuel and falls off to 3k until it picks up enough fuel again. This what I have done:

1) Checked filters in the tanks - there were none
2) Fresh gas, ran dry gas and fuel system cleaner through about 1 tank of gas
3) New line and squeeze bulb from tanks (old one was hard and leaking some air)
4) Rebuilt fuel pump
5) Cleaned carbs with carb cleaner with engine running. (Did not remove or otherwise service carbs - they look squeaky clean)Note that when I sprayed cleaner in to the top carb, engine would cough and sputter until it digested the cleaner, but when I sprayed into the lower carb, engine was much less affected.
5) New spark plugs
6) Replaced all hose clamps on fuel lines
7) Temporarily removed in line fuel filter and replaced with piece of copper tubing - this seemed to make some improvement (did not starve as hard or fast).

The high speed starvation problem is still there. The engine starts much better and has had no problem restarting now. It does stumble and surge some below 3,000 rpm. It runs like a champ otherwise - very smooth between 3000 and 5500.

Thoughts, anyone?

Thanks

 

[RayGottsleben]

Re: 1988 Mariner 50 fuel delivery problem?

I found the problem. Looks like the previous owner replaced a fuel line with one that was manufactured for use as a vacuum line and not a fuel line. At high speeds, the line would collapse on itself and pinch off the fuel flow. $2.00 and ten minutes fixed it once I figured it out.