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90 hp bogs at full throttle

C

cjorg

New member
I am new to this forum and hope someone can help me with a problem.
I have a 2016 90 hp Merc, at the end of last season it started fine and ran fine at low speed and just on plane. When I gave it more throttle it bogged as if not getting enough gas. I replaced the inline fuel filter and problem solved. Had it in the water for the third time this season and same problem. I have an inline water fuel separator and it is clean, no water, no sediment. I find it very hard to believe the filter I replaced last year could be bad as I only put about 15 hours on it since it was changed. I have checked pulg wires and they are tight at both ends, looked for any loose wires and can’t see any. This engine is engine only has 54 hours on it. I am going to try replacing the filter again but would appreciate any ideas I can get as it seems really odd the filter would fail this quickly.
Thanks for any help I can get.
Chris
 
I am having a similar problem with a 1991 75 hp Merc. It runs well at idle and up to about 80% of WOT and will run all day long but if I go to 100% WOT it will run there for maybe 20-40 seconds before it suddenly loses power and pretty much just dies. I also have noticed that if I am cruising at maybe 25-30 mph and then take a really hard corner, it will also die. Anyone have ideas? I have inspected everything from the inlet screen in the fuel tank to the carbs and believe all hoses to be in good shape and leak free. Primer bulb gets firm and does not collapse when there is an issue. I have a small in-line filter that is brand new. I have NOT changed the fuel pump membranes yet; I inspected them and they look pretty good. I may do the fuel pump rebuild next. I cleaned the carbs really well and they look to be in great shape.
 
2 completely different engines. One is 2 stroke carburated the other 4 stroke EFI.
Both probably should be on different threads...

For both of you:
I'm assuming built in tanks....
1) Verify the tank vent is not plugged. Simply loosen or remove the cap & try again.
2) Verify the anti-syphon valve is not corroded or plugged.
3) Veify the pick up tube in the tank is not plugged.
4) Do you have the cheap crap gray fuel line? It's junk & by code never should be run from a permanent/built in tank.

For cjorg:
You replaced the inline filter last season. If you have a substantial amount of crud or corrosion in an aluminum tank it could be plugged again.
Regarding your water seperator, you say it's clean, no sediment or water. Are you just draining a petcock on the bottom (if equipped) or unscrewing & replacing the element?

For birkato:
Do you have a water seperator & if so have you checked it?
 
OK thanks for pointing out we don't have similar engines. I do not have a water separator. I have an external tank (not built in). I have inspected it for water and there is none, also have drained the carbs into a glass bowl and no water in carbs.
 
Plastic tank? The pick-up cracks near the top & creates an air leak. This slowly allows air in until it quits pulling fuel.
Cheap crap gray hose? The interior lining deteriorates & plugs it.

If it boggs in a hard turn, I assume the fuel level in the carb is too low & fuel surges to one side effectively lowering the fuel level & creating a momentarily too lean condition. Constant running with a lean condition will cause you to burn the engine down
 
Droid said:
Plastic tank? The pick-up cracks near the top & creates an air leak. This slowly allows air in until it quits pulling fuel.
Cheap crap gray hose? The interior lining deteriorates & plugs it.

If it boggs in a hard turn, I assume the fuel level in the carb is too low & fuel surges to one side effectively lowering the fuel level & creating a momentarily too lean condition. Constant running with a lean condition will cause you to burn the engine down
Click to expand...
If you found curved tan colored objects in your fuel supply caused by the above, Pull your fuel filter and cut it open. You probably will find it full of these chips and sections of the fuel line....time for a new one and better fuel line.
 
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