Mercruiser 260...acceleration problems

[emsfire138]

I have a 1983 Celebrity 176 with a 5.7 liter Mercruiser 260. The problem is in acceleration. This boat has quite a bit of bow lift upon acceleration. When the bow comes up alot (outdrive trimmed all the way down), the engine sounds very "bogged", and sometimes "coughs". It just seems to have a hard time getting on plane. I wouldn't think this should be an issue with 260hp in a 17' boat. I do know that the outdrive has a 1.3:1 gear ratio, so the top-end will obviously be better, but shouldn't 260hp still be more than enough for this boat? Could it be a "fuel slosh" issue in the float bowls, or just sticking floats? (Quadrajet carb) Is there anything I should try? I have thought about an EFI retrofit, but would like to find a "cheaper" fix. I am running a 19 pitch 3-blade stainless prop - would changing to an 18 pitch 4-blade make much difference?

 

[Bondo]

Re: Mercruiser 260...acceleration problems

Check the Color of your Spark Plugs.... That'll tell you whether you have a Carb, or Fuel Issue going on.....<br />You're looking for a Light Cream + Coffee Brown....<br />A Prop designed to Lift the stern more would help... What is your WOT RPMs ????

 

[airman]

Re: Mercruiser 260...acceleration problems

Make sure that the boat isn't full of water. A lot of glass boats have completely sealed compartments filled with foam so they won't sink. Over the years water finds its way in but can't get out and pretty soon your boat has an extra 1000lbs of water on board that you didn't know about. 260HP is tons of power for a 17'boat.

 

[Ribfan]

Re: Mercruiser 260...acceleration problems

Do you have your boat left on a moorings?<br /><br />Because i had the same problem with my boat, only to find out that so much rubbish grew on the bottom caused it all.<br /><br />Got the boat taken out of the water scubbed off and re-antifoul, made a huge difference. Now she planes easy and gained an extra 12 knots in speed.<br /><br />Stuart

 

[emsfire138]

Re: Mercruiser 260...acceleration problems

Thanks for the input...the boat is stored on a trailer in a garage, so the bottom is clean. I always leave the plug out when it's out of the water. When the boat is on the trailer, I've shaken it to see if I can hear any water inside, but I can't. Is there a reasonable way to check for water in the hull without pulling the floor? This seems to be a pretty heavy boat, but it will still do close to 60mph, it just doesn't like to "jump out of the water" very fast. The way that the engine sounds makes me think it's not getting enough fuel when the boat is at an angle (bow lift). Runs great otherwise????? <br />I don't know if a different prop would help here, like I said I am considering trying an 18 pitch 4-blade. Does a 4-blade give better acceleration than a 3-blade?

 

[bwright]

Re: Mercruiser 260...acceleration problems

I just had a simialar problem with my boat it would run great but in rough water on the down side of the wave. It ended up being the anti-siphon valve in the fuel tank. I changed and checked many parts before giving up and bringing it to the shop and that what they found in a matter of minutes. They said it was a collapse spring in the valve. Something to check anyway.