FX-1 Chopping issue

E350

E350

Location
Sacramento Delta
I am the least knowledgeable person on the forum, but yesterday, riding for the first time this season (dude I am so sore today), my FX1 would die at full throttle racing my wife.

Fx1Dave said it was likely a lack of adequate fuel delivery at full throttle. So, I am now taking the carb out to look first at the screen in the carb and then at the metering pin and seat.

YRMV.
 
P

Penguin

Location
Atlanta
I pulled it apart yesterday and cleaned out the carb filter ports, but I could be missing something. Maybe I just need to get a rebuild kit
 
E350

E350

Location
Sacramento Delta
Holy crap! I am grateful that I started trouble shooting at the fuel tank. I have a load of crap in the tank.

The a Blowsion fuel filter/screen at the end of the fuel pickup tube is clogged.

I do have another filter inline on the top of the fuel tank as well as the oem fuel filter on the side of the engine compartment. All of these should have protected the screen inside the SBN44 carb.

Good luck with your troubleshooting.
 

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P

Penguin

Location
Atlanta
Thanks for the info. I definitely need to get into the gas tank and check it out, it seems to be flowing good and with the consistency of the chop, I’m wondering if it’s something else!
 
DylanS

DylanS

Gorilla Smasher
Location
Lebanon Pa
Funny enough the other day on a buddies ski he was having a very similar issue where the ski would run fine but run out of fuel wot and bog down almost enough to kill the ski.
I’ve seen it where debris would clog up filters before under suction but in his case his filter legitimately just could not flow enough to feed his carb rack. When watching the filter while riding the ski it remained full and seemed to flow well but lo and behold it was simply to restrictive to keep up after about a month of use and no major visible dirt.
Anyways I just watched your video and that’s an electrical problem, not fuel.
Start on that rabbit hole, you can use a multimeter to test most of the components and if you don’t find anything obviously wrong try swapping the cdi with a spare if you have one.
 
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E350

E350

Location
Sacramento Delta
One thing I haven't checked yet is the Check Valve which when working fully permits the same volume of air to enter the fuel tank to compensate for the vacuum which would otherwise be created by the equal volume of fuel being sucked out of the fuel tank by the vacuum created by the carburetor's fuel "pump" (which is not really a pump but a suction device).

Higher RPMs = Higher Volume of Fuel being sucked out of the Fuel Tank = need for the Check Valve to open fully to permit the entry of a Higher Volume of Air into the Fuel Tank.

Is it possible that a Check Valve is working to compensate for the volume of fuel being sucked out by the carb at low RPMs but not opening up full at High RPMs thereby causing a vacuum which overcomes the vacuum created by the carb and, as a result, creates a fuel starvation condition at WOT?
 
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DylanS

DylanS

Gorilla Smasher
Location
Lebanon Pa
E350 said:
One thing I haven't checked yet is the Check Valve which when working fully permits the same volume of air to enter the fuel tank to compensate for the vacuum which would otherwise be created by the fuel being sucked out of the fuel tank by the carburetor.

Is it possible that a Check Valve is working but not working completely thereby causing vacuum and thus fuel starvation at WOT?
Click to expand...
they’re normally shot or they’re not haha but if you really want to be certain just bypass it and run the ski once to find out
 
E350

E350

Location
Sacramento Delta
@Penguin How is your troubleshooting going?

My screen was perfectly clean. @Big Kahuna did you once have a fuel starvation at WOT due to a screwed up diaphragm? Could the bloated diaphragm be the problem? I replaced it but haven't ridden the ski yet. Photos below:

IMG_2782.jpgIMG_2783.jpgIMG_2786.jpgIMG_2790.jpg

Look at the rust on that metal plug! I hate ethanol fuel. Any suggestions?
 
P

Penguin

Location
Atlanta
E350 said:
@Penguin How is your troubleshooting going?

My screen was perfectly clean. @Big Kahuna did you once have a fuel starvation at WOT due to a screwed up diaphragm? Could the bloated diaphragm be the problem? I replaced it but haven't ridden the ski yet. Photos below:

View attachment 457063View attachment 457064View attachment 457065View attachment 457066

Look at the rust on that metal plug! I hate ethanol fuel. Any suggestions?
Click to expand...
Did you take carb/ brake cleaner to all of the ports too?
 
E350

E350

Location
Sacramento Delta
I did not clean out the carb ports with carb cleaner yet for the following reason. I have four filters/screens protecting the ports in the carb:

1. In tank pick up screen;
2. Aftermarket triangular In line fuel filter;
3. OEM Yamaha fuel filter on the inside lip of the engine compartment;
4. In carb screen.

The in carb screen was impeccably clean, so although I considered taking the fuel metering lever, spring and pin out and even the High and Low speed screws I didn't because I force myself to be methodical in my troubleshooting and fix one thing at a time. Otherwise I risk the possibility of introducing more problems by my attempted "fixes."

Since the pump diaphragm looked bloated and likely too weak to pump fully at WOT, I replaced that and will test it and will report back.
 
DylanS

DylanS

Gorilla Smasher
Location
Lebanon Pa
E350 said:
I did not clean out the carb ports with carb cleaner yet for the following reason. I have four filters/screens protecting the ports in the carb:

1. In tank pick up screen;
2. Aftermarket triangular In line fuel filter;
3. OEM Yamaha fuel filter on the inside lip of the engine compartment;
4. In carb screen.

The in carb screen was impeccably clean, so although I considered taking the fuel metering lever, spring and pin out and even the High and Low speed screws I didn't because I force myself to be methodical in my troubleshooting and fix one thing at a time. Otherwise I risk the possibility of introducing more problems by my attempted "fixes."

Since the pump diaphragm looked bloated and likely too weak to pump fully at WOT, I replaced that and will test it and will report back.
Click to expand...
If this doesn’t work try running just one filter, new preferably, or none for a short run. You may have too much restriction in your filter setup to supply your carb at WOT especially after that gunk in the tank.
 
Myself

Myself

manic mechanic
Location
Twin Lakes AR
E350 said:
@Penguin How is your troubleshooting going?

My screen was perfectly clean. @Big Kahuna did you once have a fuel starvation at WOT due to a screwed up diaphragm? Could the bloated diaphragm be the problem? I replaced it but haven't ridden the ski yet. Photos belowView attachment 457066

Look at the rust on that metal plug! I hate ethanol fuel. Any suggestions?
Click to expand...
That's the wrong gasket. It will leak fuel right where you can see part of the db shaped o'ring.
 
Myself

Myself

manic mechanic
Location
Twin Lakes AR
The flat rubber gasket. You should NOT be able to see that piece of o'ring peeking out in that top right corner. They always include that one but it goes in VERY FEW carbs. You need the one with the smaller teardrop shaped hole.
 
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