Fuel not keeping up with engine, help.

[Ace]

I had a fuel starvation issue so i took apart the carbs not majorly, I followed the youtube vids and forums since i had never done it. It would start and run good but my inline fuel filter would go empty and shed die, had to wait for fuel to fill up filter again to start, it was a constant issue couldnt really ride it anymore. I took apart the carbs and cleaned them, installed them and now it just cranks and cranks -_-. So I made it worse some how, i did not mess with idle screws, I cleaned the jets and needles and sprayed the carbs with cleaner. any clues?

[Triple Jim]

If you cleaned the carburetors without taking out the idle screws, you didn't complete the job. If the idle passages are clogged, you'll have trouble starting and idling.

As far as the inline fuel filter looking empty, when the float valves open, air can get back up from the float bowls into the fuel line. That doesn't necessarily mean something is wrong. A way to check is to remove the fuel line at the carbs and suck on the petcock's vacuum line, and check to see if you get a good stream of gasoline out the line.

If your gas cap's vent system is clogged and not letting air into the tank, you will have fuel flow problems. When you're checking as above, let it run into a can for a while and see if it keeps flowing well. If you suspect it's slowing down, open the cap and see if it changes.

[DannoXYZ]

Yeah, sounds like carbs aren't the problem as fuel isn't even reaching them. Something upstream is slowing down fuel-flow. Test usual areas:

- tank venting - do cap-mod NOW, don't waste time with anything else.
- petcock - check this after cap-mod, make sure fuel flow continuously when vacuum applied.

[Ace]

Thanks guys! Well i sent my carbs to motorcycle mechanic and he said he had to calibrate the floats, i installed them abd she fired right up! But still fuel issue. I took out tje petcock, looks good not dirty or clogged but i still ordered a new one to be on the safe side. Il do the cap mod when im free from work. Thanks for ur inputs gentlemen.

[Ace]

The venting holes were clogged i cleared them and fuel flow is way better but still not how it use to be or should. Petcock is clean but ordered one to be safe, i could not get airbox to connect to carbs. Could this cause an issue in fuel flow from tank to carb?

[DannoXYZ]

If you don't have good seal between carbs and air-box, that won't be any issues with fuel. You'll have premature engine-wear due to sucking in unfiltered air.

Did you test petcock fuel-flow? Does it flow continuously with vacuum applied?

Without testing, but just swapping parts, you'll never know what was bad and causing your problems. There are many brand-new parts out-of-box that are bad. Those needs to be tested too and returned if bad.

[Ace]

I suked on vacum into the petcock abd yes had a nice. I went on a ride and starved so i hoped off and suked vacum but this time it felt like it clogged up. I had to blow and suk to get fuel into the inline filter. I ordered a new petcock and installed it, does the exact same thing and i also got the airbox hooked up. Im thinking theres a prob with my tank it does have some rust but my fuel is clean like water and i can blow freely through the air vents. Im running out of ideas. Thanks for the replys gentleman.

[Ghostt]

Originally Posted by Ace

The venting holes were clogged i cleared them and fuel flow is way better but still not how it use to be or should. Petcock is clean but ordered one to be safe, i could not get airbox to connect to carbs. Could this cause an issue in fuel flow from tank to carb?

Sounds like it could be a venting issue, no worries it's a free and easy fix,

You need you to disassemble the gas cap and remove the two small red diaphragms, assuming this is your only problem.

The diaphragm gets hard and losses it's flexibility and gets stuck, and doesn't allow proper venting.

IMHO this modification should be done regardless to prevent future problems whatsoever.

They are ment to vent the tank, but in the case of an accident not allow gas to leak out, but more often cause problems then they fix.

Here are some pictures to help you.

The plastic piece houses the two small red diaphragm pieces, this one being mine, they are already gone, and you can leave the plastic piece out all together, as I'm going to do now.

Some things to watch out for are, there are 5 small springs under the round collar, and a small round collar as well on the locking mechanism, don't lose any of them.

Good luck.

[Triple Jim]

It's almost funny that there are so many parts in the cap. Not quite, but almost. I have a simple cap on my DT100, with a Tygon overflow tube that goes down along the frame and heads toward the ground, and a little restrictor orifice in the tube so when I hit the brake I don't get much out the overflow. If I get irritated enough at my stock 250 cap I may do the same thing to it.

[Ace]

I actually got a 1980s kz650 tank and adapted it to the ninja since i want a vintage cafe racer look anyways. Petcock for that tank is gravity fed and no vacuum needed. Its running good.