'89 Mercruiser 4.3 Bogs in midrange, Runs great idle and WOT

[Tanker_01]

Either weak fuel pump or a restriction (antisiphon valve, fuel line collapse, tank pickup tube clogged)
Check pressure 3-7 psi

This is my prime suspect in my mind right now. What is the best way to diagnose what is my issue? I have just replaced the fuel pump and I verified the lines to and from it are not collapsed or restricted in any way. Since I have an in-line fuel filter and the filter in the carb would it help to maybe eliminate one of those to make less restriction? I would think that I am restricted by whichever of those is most restrictive only. The one in the carb is supposed to be there so should I try removing the in-line one?

For the antisiphon valve on the top of the tank is there a way to test it to see if it is functioning correctly? and I am guessing the tank pickup tube is right under that correct?

 

[Tanker_01]

Woah wait now that I look at it that carb parts breakdown document doesnt even have the piece on top of the power valve that mine has. everything else in that is identical to mine other than the one extra piece. The piece I have looks kind of like this one in the attached picture.

 

[alldodge]

For the antisiphon valve on the top of the tank is there a way to test it to see if it is functioning correctly? and I am guessing the tank pickup tube is right under that correct?

Yes, on top the tank. It should take very little vacuum to open it in the flow direction. Clean up, then blow toward the barbed end. Can also use a vacuum hand pump and it should not exceed 1 inch hg

 

[Rick Stephens]

If the problem is still as the title says: "'89 Mercruiser 4.3 Bogs in midrange, Runs great idle and WOT" then the problem is still in your carburetor.

 

[Tanker_01]

If the problem is still as the title says: "'89 Mercruiser 4.3 Bogs in midrange, Runs great idle and WOT" then the problem is still in your carburetor.

If you have read my responses at all you would know this is no longer the case... Carb has been taken apart and cleaned and now the issue has reversed. Runs great at low RPM but is dying at WOT.

 

[Rick Stephens]

If you have read my responses at all you would know this is no longer the case... Carb has been taken apart and cleaned and now the issue has reversed. Runs great at low RPM but is dying at WOT.

And that doesn't make you still think the carb is not right? You worked on the carb and changed the problem to a different but still obviously fuel issue.

 

[Tanker_01]

And that doesn't make you still think the carb is not right? You worked on the carb and changed the problem to a different but still obviously fuel issue.

Holy crap man like 3 replies up I specifically say I suspect it is a fuel issue and ask for some suggestions as to what it could be between the carb and the fuel tank. If you are not going to try to be helpful could please stop trying to just poke holes in this thread and go somewhere else that appreciates your poor reading comprehension skills. Thank you.

 

[alldodge]

And that doesn't make you still think the carb is not right? You worked on the carb and changed the problem to a different but still obviously fuel issue.

Have to agree

 

[Tanker_01]

Have to agree

I am no longer troubleshooting carb issues after cleaning and rebuilding it. I am chasing a possible fuel restriction issue per my responses above.

 

[nola mike]

Then check the fuel pressure as suggested, and/or try running off of a remote tank.

 

[Rick Stephens]

Holy crap man like 3 replies up I specifically say I suspect it is a fuel issue and ask for some suggestions as to what it could be between the carb and the fuel tank. If you are not going to try to be helpful could please stop trying to just poke holes in this thread and go somewhere else that appreciates your poor reading comprehension skills. Thank you.

Bye