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Old 09-06-2009, 06:38 AM   #1
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Default Engine richens after refueling

I keep having the same problem for a while now. Engine runs fine but i keep getting a rich setting just after refueling and needs about 30m into the track to clean up. The same thing happens to my brothers engine.
I drive a Sirio Kanai EVO 4 and my brother RB WS9.
Anyone knows what causes this 'problem'?

Sometimes it might flame out...unless i keep blipping the throttle for the first 10m and then take it easy for the next 20-30m and try clearing it up at the jumps.
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Old 09-06-2009, 08:34 AM   #2
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Are you sure it becomes rich? The engine should lean during refueling since the tank lid is open and you lose the back-pressure.

I usually blip the throttle and take it slow for about 5 seconds after refueling.
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Old 09-06-2009, 08:37 AM   #3
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are the motors still breaking in? how many gallons do you have on them?
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Old 09-06-2009, 08:44 AM   #4
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is your pit guy letting the lid slam back down on the tank? if so this is your problem. if you let it slam down it will throw more pressure into the tank causing the fuel to get pusshed into the motor. im really bad at explaining it. maybe someone else could help me out
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Old 09-06-2009, 08:46 AM   #5
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WEatherbB is right, normally an engine will lean out after fueling. Especially if you have to make right turns out of the pits, or fill it to the very brim. That is due to getting a little fuel in the pressure tube, causing it to lean further. Assuming you pressure tube comes out the side.
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Old 09-06-2009, 08:57 AM   #6
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This is not the case. If it became lean it would be for the first 5-10 meters...same thing as when upsite down. The engines have around 2G through them.

You have a point on the lid slamming on the fuel but again...this is the case on other cars but don't richen up.
I've read somewhere about pressure line length... And in my case it's around 15cm/6inch
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Old 09-06-2009, 11:43 AM   #7
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This is normal behaviour.
Unless you really take youre time and the tank is empty when refueling, yes then it will get leaner.
After refueling pressure will be higher, and the engine will be fed more. same reason why you experience leaning out at the end of a tank.

when full it will be richer, when allmoust emty - it will be leaner.

How to cope: tuning when tank is half full, and dont fill the tank to the rim, nor run it dry.
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Old 09-06-2009, 12:12 PM   #8
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how much fuel line do u have from tank to the engine?
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Old 09-06-2009, 12:30 PM   #9
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Over filled at pit stop & letting the lid snap shut will not only push fuel into the pressure line it will force extra fuel into the eng case. Feels just like when you remove the pressure line & blow in it to prime the lines & blow too long filling your case with fuel when you first start the motor for that day. Easiest fix is tell pit guy not to fill the tank the tank to the very top,stop at the bottom of the verticle round part the lid sits in or just under & dont snap the lid down just hold onto the zip tie till it shuts then push down with thumb. Done right & its only 2-3 seconds longer for a normal pit man than it is for a pit guy that is spaztic & causes other problems like no brakes for 1/2 a lap with that bionic fuel bottle hand.
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Old 09-06-2009, 05:26 PM   #10
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Quote:
Originally Posted by casevac View Post
This is normal behaviour.
Unless you really take youre time and the tank is empty when refueling, yes then it will get leaner.
After refueling pressure will be higher, and the engine will be fed more. same reason why you experience leaning out at the end of a tank.

when full it will be richer, when allmoust emty - it will be leaner.

How to cope: tuning when tank is half full, and dont fill the tank to the rim, nor run it dry.

well said casevac.

tank lid closing too fast...
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Old 09-06-2009, 10:07 PM   #11
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Will something like a fuel filter help on the pressure line as Mugen used to make for the 5R??
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Old 09-06-2009, 10:14 PM   #12
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Quote:
Originally Posted by vti-chris View Post
Will something like a fuel filter help on the pressure line as Mugen used to make for the 5R??
Longer pressure line or Mugen pressure chamber will sometimes help to prevent this. The chamber will add volume to the pressure line and absorb the high pressure build up or spike of snapping the lid shut with a full tank.
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Old 09-07-2009, 08:13 AM   #13
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This is what i was thinking as well.
Anyone has any input on this one?
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Old 09-07-2009, 09:01 AM   #14
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Your tune could also be off some making this problem worse. Probably too rich on the bottm and too lean on top. Does the motor come in for a pit stop with a high idle?

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Old 09-07-2009, 09:06 AM   #15
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Engine is perfectly tuned...no mistakes there.
Slightly rich on top to keep temps down due to hot weather but LSN is set so it doesn't lose any power when launching from a 10 sec idle.
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