bogging 1978 85hp. v-4 evinrude

hi ! boat ran great for 10min on first outing then the timer base got stuck, cleaned and reinstalled timer then took back out motor still bogging replaced plugs cleaned fuel filter and installed inline filter was running on old fuel..<br />made up new tank of fuel (flushed system fuel)<br />engine on muffs runs great but in the water under accelertation wot bogging still. suggestions??

Re: bogging 1978 85hp. v-4 evinrude

Welcome mastiff!<br /><br />Bogging down usually is a fuel delivery problem. Can be caused by dirty carbs, fuel pump problem or fuel line leaks. You can test this by taking a spray bottle of fuel mix and giving the carb throats a spray of fuel. If the engine picks up, problem with fuel delivery.<br /><br />Make sure the fuel tank is venting and the fuel line to the engine is good with a good primer ball. Check your fuel lines in the engine are not hard and are making good solid connections. <br /><br />Check the choke plates are opening after choking to start. <br /><br />If you don't know when the carbs have been overhauled last or if the engine sat for a while before you got it, it would be a good idea to overhaul them including new kits and a soaking out.<br /><br />On the ignition end, make sure each cylinder spark will jump at least a 7/16" gap with a strong thick spark.<br /><br />Engines usually run great on muffs because there is no back pressure against the cylinders as there would be if the engine was in the water. The exhaust of the engine must push it's way through the water to get out...thus...backpressure.