boat bogging down

[PABassFish007]

We have an 89 evinrude 90hp that works flawlessly 25% of the time, the rest of the time the boat will only gain enough power to plane by squeezing the (already rock solid) primer bulb, usually 3 pumps and its on plane and slows back down.. weve replaced the fuel line from motor to tank, as well as the fuel pump. Problem is still there.  Does anyone have suggestions? Thanks

[MN Fisher]

Sounds like a dirty fuel-filter to me.

[flyfisher]

i'd have to agree with MN fisher.  Motors need three things, fuel spark and air.  If it changes when you force the fuel in that would be my first place to look.

[Ski213]

As said above sounds like it is likely lack of fuel for one reason or another. Is there anything different about the 25% it runs well or is it just random? Do you have a way to check the fuel pressure between the pump and carbs?

[813basstard]

“Works flawlessly 25% of the time...”

 

I’d say it’s time for a new one 

 

 

[Todd2]

Mine did this intermittently also a few years back and I changed the filter and plugs and it was fine. One of my old plugs was loose when I went to change it but went ahead and swapped the parts. I always wondered if the problem was just a loose plug. You could check that.

[PABassFish007]

Changed fuel pump, and spark plugs.. same problem

[Way2slow]

A couple of suggestions, first do a compression check and see if you have even compression on all four cylinders, probably around 90psi.

 

Next, when it's bogging, just hold WOT for about a minute, if it's still bogging, cut the switch off while still at full throttle.  Watch out for the backwash a lot of smaller boats will have.  Pull the cover off and pull all four spark plugs out and look at them.  They should be dry and the same color.  If one is wet, or a lot darker, you have firing problem on that cylinder, possibly a bad power pack, coil or wire.

If they are all dry but one darker, that could be a dirty carburetor or fuel delivery problem.

 Problems like this sometimes requires professional diagnostics because there is a host of things that can cause it.

A friend of mine bought a 225HO last year and it was doing similar stuff and said he had changed power packs and almost everything on it  His 225 non HO motor ran faster a got out of the hole much better, so he had swapped almost all that motor over to the HO, with no help.  I told him to swap the flywheels on them, that he might have a bad magnet in it, I had run into that problem before on those motors.  He thought I was full of it but swapped them anyway, that fixed his problem.  

Now, not saying yours has a bad flywheel or magnets, I'm just saying you can spend a bunch of money just trying shotgun trouble shooting and just throwing parts at it.  He had a good running spare motor he could swap from, start buying a swapping parts get very expensive.

 

I will say, power pack problems on those V4 motors are not that uncommon.

[PABassFish007]

Found one hose under the carb broke off, fixed and took to the lake. The boat came right up to plane ran around well, HOWEVER it now planes, bogs down, planes, repeats this cycle. Almost as if it is taking too long to fill the Carb Bowls with fuel. We also noticed gas very slowly leaking when squeezing the primer bulb from the carburator gasket.  Could this fix the entire issue?

[redmexican5081]

On 7/25/2020 at 4:32 PM, PABassFish007 said:

Found one hose under the carb broke off, fixed and took to the lake. The boat came right up to plane ran around well, HOWEVER it now planes, bogs down, planes, repeats this cycle. Almost as if it is taking too long to fill the Carb Bowls with fuel. We also noticed gas very slowly leaking when squeezing the primer bulb from the carburator gasket.  Could this fix the entire issue?

Gas leaking out when you add additional pressure by squeezing the ball might also mean air being sucked in when the motor is drawing by itself. It might be time to replace the gaskets.

[Heartland]

Have you ran any good carb cleaner through it?  Sounds like a stuck float to me.

[rejesterd]

You changed the pump and plugs, but how about the filter?

[billmac]

I just had this problem.  Rebuilt fuel pump.  Changed primer bulb and fuel lines.  No improvement.  Finally I changed out the gaskets, needles and seats in my carbs, and that did the trick.  I think perhaps one of the needles was sticking unless I crazy cranked the primer bulb.  You should see if you are getting adequate fuel to the carbs.