89 4.3 mercruiser bogs at wot

beninlou · Jun 18, 2009

i got a 89 larson with the 4.3 mercruiser.took the boat out for the first time and run really bad died while idling i could play with the throttle and get it to take off but would only run at low rpms and stall when i backed out of the throttle.took it home and pulled the fuel filter out of the carb and it was clogged.put a new one in and took it back to the lake.now starts great idles fine and runs good at half throttle.but when cruising along at about 3000 rpm and push the throttle down to wot.and the boat begins to bog and pop out of the carb.back the throttle up a little and takes right back off smooth.any help would be great.thanks ben

Bondo · Jun 18, 2009

Re: 89 4.3 mercruiser bogs at wot

Ayuh,... Either there's more Crap in the fuel filters,.. Or in the Carb itself...

beninlou · Jun 18, 2009

Re: 89 4.3 mercruiser bogs at wot

besides the screen in the carb itself.where can i find any other filters?

Bondo · Jun 18, 2009

Re: 89 4.3 mercruiser bogs at wot

Ayuh,... I'd think there should be a cannister type filter just before the fuel pump...

beninlou · Jun 18, 2009

Re: 89 4.3 mercruiser bogs at wot

theres not every boat i had before this one has had a screw on filter.i guess im gonna pull the carb and see what it looks like.thanks for the help

beninlou · Jun 19, 2009

Re: 89 4.3 mercruiser bogs at wot

took the boat back out tonight now i have a new problem added to the bogging at wot.when setting still you can see steam coming out of the water.i know this is bad my question is where should i start.can a intake gasket cause this or should i just go ahead and pull the heads?and thanks guys i get more help on this web site then from anything else.

cooter2506 · Jun 19, 2009

Re: 89 4.3 mercruiser bogs at wot

IS it over heating? Have you run it on muffs at home to see if your impeller is pumping water?As far as it bogging. Did you check the pick up screen in the fuel tank. If you are getting crud as far as the carb then that has to be blocked also. If you dont have a water seperating fuel filter you NEED one.

beninlou · Jun 19, 2009

Re: 89 4.3 mercruiser bogs at wot

its not overheating.pumps plenty of water and there is no water in the oil.

gadget73 · Jun 20, 2009

Re: 89 4.3 mercruiser bogs at wot

Hot exhaust gas will make the water steam. May not be a problem, every boat with through-hulls I've ever seen has some steam action. If its pumping, not overheating, and not making milkshakes in the crankcase I wouldn't jump to a head or intake gasket issue. If you're hearing pops and bangs in the exhaust, start with riser gaskets but I think your issue is squarely a fuel one. Worry about the other stuff (if its still there) after getting the fuel issue sorted.

beninlou · Jun 20, 2009

Re: 89 4.3 mercruiser bogs at wot

so if it is a head gasket would that cause it to run bad at wot or would it run bad all the time?maybe i should just start with rebuilding the carb before i tear into the motor.

Bondo · Jun 20, 2009

Re: 89 4.3 mercruiser bogs at wot

maybe i should just start with rebuilding the carb before i tear into the motor.

Ayuh,... Seeing that you don't know that the motor needs a Headgasket,...
Why not Fix what you Know is screwed up 1st...

beninlou · Jun 20, 2009

Re: 89 4.3 mercruiser bogs at wot

rebuilt the carb no luck same problem still.on to the next idea

beninlou · Jun 21, 2009

Re: 89 4.3 mercruiser bogs at wot

this boat has the mercruiser thunderbolt ign.could a bad pickup in the dist cause this problem.

89 4.3 mercruiser bogs at wot

Seaman Apprentice

Moderator

Seaman Apprentice

Moderator

Seaman Apprentice

Seaman Apprentice

Senior Chief Petty Officer

Seaman Apprentice

Petty Officer 1st Class

Seaman Apprentice

Moderator

Seaman Apprentice

Seaman Apprentice