Mercruiser 260hp

[bernieb]

In the process of looking for a gas starving problem in this chev 350 I/o I may have messed up the carb but not sure......bought a carb kit,installed some of the parts(rochester 4 bl)not a pro on the carb mind you.The engine is good and tight and ran excellent before the missing problem, as for the gas starving I found four leaves in the gas tank and that problem is solved.Now for engine performance ...idle okay but taking off with full load 21 foot '82 sonic (heavy boat) and putting throttle all the way down and men up front can't get on plane for 5 minutes, use to be only seconds .This engine is a late 60's and has points and something else is strange ,engine is running hotter than before and rpm is only 3300rpm on plane wot and after a 30 minute run and shut down and on restart the battery sounds like its close to being dead but 5 minute rest starts fine.I did move distributer in looking for the original problem.Is it better to have gas pushed or pulled through a fuel separator cannister? have changed fuel pump ,fuel hoses.The carter fuel pump has a hose going to carb. Thanks for considering

 

[DJ]

Re: Mercruiser 260hp

bernieb,<br /><br />I'm not so sure your problem is carburetion or fuel starvation.<br /><br />For some reason, your engine is not reaching full rpm. My first thought would be to put a vacuum guage on a manifold port (not carb.) At idle it should hold a STEADY 16-18 inches of vacuum.<br /><br />On accel., it should drop considerably yet still be steady.<br /><br />If I had to guess, I would say that your timing is off or your advance (timing) devices on your distributor are not functioning properly.<br /><br />I would also perform a cylinder balance test by shorting out one plug wire at a time and take note of rpm. drop. Each cylinder should drop the rpm the same.

 

[snapperbait]

Re: Mercruiser 260hp

Hi Bernieb... Sounds like you've got a few minor issues contributing to the performance problems your having... Grab yourself a service manual.. If you don't have a service manual, Get one!...(you'll need it)..<br /><br />Since you turned the distributor and its "missing", the distributor is where you should start tracking down the problem... <br /><br />First order of buisness would be a basic ignition tune up.. Replace the points & condinser, cap & rotor, spark plugs, and maybe the plug wires too... While you are changing the points, remove the plate that hold the points inside the distributor and have a look at the advance weights and springs to make sure they move properly and are not rusty or broken springs...<br /><br />Once you have the distributor squared away, get a timing light connected, start the engine and set the base timing to spec... Once you've set the base timing, increase the RPM's and watch the timing marks with the light to make sure the timing is advancing to were it should be.. <br /><br />Next, engine running too hot.. New impeller in the raw waterpump inside the outdrive is the first step.. If you have'nt serviced it in two years, it's over due for replacement... I would replace the thermostat as well... If you do these two things and still have the engine heating up, you may have some blockages in the water passages of the exhaust manifolds which is not uncommon...<br /><br />As for the fuel filter/water separator I would say "pulled"....

 

[DJ]

Re: Mercruiser 260hp

bernie,<br /><br />I agree with Snapperbait. Rememember, a mistimed engine can make it run hotter than normal.

 

[bernieb]

Re: Mercruiser 260hp

I will follow the professional answers posted to my dilemma on this boat and will get back with my results ,that is, if I don't run out of money first.thanks for sharing your skills.