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Fuel filter or bad tank cap/valve...intermittent sputtering & bulb collapse
Posted on 9/3/26 at 10:52 am
Posted on 9/3/26 at 10:52 am
90 HP Yamaha 2-stroke. Will run fine all day and then lose power at high rpms. Takes a bit to get the bulb back to pressure. Replaced fuel lines, fuel/water separator and fuel pump. Should I go ahead and replace the filter on the motor or try to troubleshoot the gas cap/tank valves/screens.
It's driving me bonkers. I tried the trick of opening the gas cap when running and it didn't "hiss"....also randomly tightening down the brass cap on the tank got it get to prime again.
This engine is driving me freakin crazy. What ya'll think?
It's driving me bonkers. I tried the trick of opening the gas cap when running and it didn't "hiss"....also randomly tightening down the brass cap on the tank got it get to prime again.
This engine is driving me freakin crazy. What ya'll think?
7
Posted on 9/3/26 at 10:57 am to Prosecuted Collins
Configure a water bottle to make a funnel and try to seal it around the gas filler. Blow in it and see if the air comes out of the vent.
if that's not it, It's either the pickup getting clogged, a bad bulb, or the filter that you have not changed. Also could be a clogged port in the carb. clean it or replace.
if that's not it, It's either the pickup getting clogged, a bad bulb, or the filter that you have not changed. Also could be a clogged port in the carb. clean it or replace.
Posted on 9/3/26 at 10:58 am to Prosecuted Collins
I had something similar happening with my Johnson. It'd run fine and then start accelerating sluggishly and sometimes briefly losing power at high RPMs. It ended up being the fuel fitting at the motor not sealing right. It'd work as long as the fuel line was in a certain position and start leaking if it were moved to the right spot.
Posted on 9/3/26 at 11:42 am to Prosecuted Collins
One thing you might check is the fuel pickup inside the tank.
The screen can get clogged with debris or varnish / blob from ethanol fuel.
Also the fuel lines themselves. Theres some bad fuel lines out there that disintegrate due to age and ethanol fuel creating tiny black specks that can clog jets and other passages within the fuel system.
Also what Motorboat said above about the primer bulbs. They deteriorate over time and theres a check ball in there that gets fricked up with age.
The screen can get clogged with debris or varnish / blob from ethanol fuel.
Also the fuel lines themselves. Theres some bad fuel lines out there that disintegrate due to age and ethanol fuel creating tiny black specks that can clog jets and other passages within the fuel system.
Also what Motorboat said above about the primer bulbs. They deteriorate over time and theres a check ball in there that gets fricked up with age.
This post was edited on 9/3/26 at 11:44 am
Posted on 9/3/26 at 12:06 pm to Prosecuted Collins
Even though you replaced the fuel lines, it still sounds like a fuel line or bulb.
Posted on 9/3/26 at 12:08 pm to Prosecuted Collins
Check the fuel line pickup hose in tank. Been there done that.
Posted on 9/3/26 at 2:15 pm to redfish99
quote:
Check the fuel line pickup hose in tank. Been there done that.
Just went through all of this too. I'll add if you have an anti-siphon valve on your pickup tube take that garbage off and replace with a regular barbed fitting. I changed every hose, bulb, fitting, pickup tube on my 150 johnson 2-stroke to no avail. It ended up being past time to remove the oil injection and mix my gas. It runs better now than it has in 10 years!
Posted on 9/3/26 at 3:00 pm to bj0969
Thanks. Gotta get this fixed. The fuel delivery system is all brand new.
Posted on 9/3/26 at 3:15 pm to Prosecuted Collins
Eliminate the fuel tank by running it off of a regular gas can, change element water separator, bypass water separator,. Those are some of the best motors Yamaha has made and I bet the solution is looking at ya.
Posted on 9/3/26 at 3:54 pm to KemoSabe65
That’s the thing! It’ll run like a top the whole day then randomly start with the fuel issue. As long as it has gas it’s aces.
Posted on 9/3/26 at 9:14 pm to Prosecuted Collins
Check the fuel line connector where it connects to the tank. I had a problem one time when the connector was bad and it was sucking air changed the connector and she ran fine.
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