2850 Engine or fuel supply appears to bog down or decrease at higher RPM levels.-gctid810343

[Guest]

We have a 1983, 2850 with a 350, 260 HP with a single engine on board. The engine is running smooth at lower RPM, but when we try to increase power, over perhaps 2500, it will bog down.

When that happens we back off the throttle and the boat recovers.

We are suspecting the carburetor or air filter, but would like to see if any of you have experienced similar before we remove the carburetor and rebuild it or buy another one.

Thanks for any information that any of you may have on this issue.

[Ruffryder]

Yes could be the carb, weak spark, lack of fuel delivery, clogged vent...

[mister_larry]

If one of your suspicions is the air filter (some of us call it the spark or flame arrestor) you can find out quickly - and for free. Take the boat out on the water, remove that filter, and run the boat up to speed. Does it behave the same way (on the same day on the same water with the same outside temperature) when running with or without the filter??

If there is no difference, the filter is fine and either fuel delivery, or spark delivery, might be the next things to check.

Happy testing.

[builderdude]

Before you pull the carburetor do a test run briefly without the flame arrestor and also without the fuel fill cap installed. Doing this will eliminate or confirm your possible "air filter" (needs to be an approved flame arrestor) and clogged fuel tank vent issues. The other thing I'd look at is the timing advance, your 83 BL is likely running a distributor that uses mechanical advance weights and they can become somewhat non functional do to corrosion or lack of maintenance.

[Guest]

We cleaned the "spark arrestor" and that took care of the problem. Had to use varnish thinner here in California, they don't allow mineral spirits any more.

Thanks for all the suggestions.

[builderdude]

Always good when it's as simple as that