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Help! What causes a flameout following a fuelstop?

Help! What causes a flameout following a fuelstop?

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Old 05-13-2012, 09:11 AM
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Default Help! What causes a flameout following a fuelstop?

What causes an engine to flame after a pitstop? Motor is running great, come in for a pitstop and when I leave pitlane it starts boggin and dies before the next turn, fire it back up and everythings fine
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Old 05-13-2012, 09:27 AM
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Before pitman sets you down try a bit of 3/4- full throttle see if that clears the engine out, this is something I do as he throws the buggy down pit lane.
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Old 05-13-2012, 09:46 AM
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Prob a rich lsn. Have your pit guy hold the car in the air after fueling for a second so you can clear it out like said above. Thats the number 1 issue i see with tuning issues, to rich on the lsn. But, re tune the engine after you adjust the lsn. Run the car for 6 minutes or so because once you lean the bottom the idle will rise.
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Old 05-13-2012, 09:59 AM
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+1 on the rich LSN. Some engines can hide a rich LSN and when you come in for fuel that cooler fuel hits the engine and it riches up. Lean out the bottom and retune.
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Old 05-13-2012, 10:09 AM
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Originally Posted by Gwoodrc View Post
What causes an engine to flame after a pitstop? Motor is running great, come in for a pitstop and when I leave pitlane it starts boggin and dies before the next turn, fire it back up and everythings fine
I am guessin mugen buggy ?

Everybody is absolutely correct , rich lsn will do it everytime
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Old 05-13-2012, 01:41 PM
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I've never really had that happen to me but I've recently started to clear my motor cause it's the cool thing to do lol
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Old 05-13-2012, 08:37 PM
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Thanks for the info, I never had this problem before and it's happened twice to me in the past two weeks. I was thinkin of adding length to the pressure line or install a gas cooler but the rich lsn makes more sence, I switched to another brand plug and re tuned the motor and I guess I got the lsn too rich. I will try to re tune it next time I go to the track.
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Old 05-20-2012, 11:49 PM
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I had a flame out after my pit stop yesterday but it was about half way through the first lap after stop, one of the guys at the track thinks it was more to do with slapping the flywheel as it was straight after a jump.
Could a rich lsn be the problem that far into the lap after pitting or hitting flywheel landing off jump.

What's some of you guys thoughts.
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Old 05-21-2012, 12:40 AM
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One of the most common issues is it's too rich on the bottom. Try opening up the top end and lean the bottom a little and if needed raise the idle a little bit. It's not uncommon to run a little lean on the bottom during a race, and trying to tune it down to idle perfectly will only leave you flamed. Some engines I've tuned for friends i found the idle screw wasn't even touching the slide in the carb, but it could be tons of things. weak clutch springs, the engine is just a pain in the butt, I find that some really fast engines seem to load up on fuel after stops, don't know why, but its happened to me before. The tank could be a problem, but usually not unless it's beat to shreds. The glowplug could be too hot for the engine and it's getting fried quickly, really common. Or the the head is shimmed too high, or the nitro content is too high or the oil content is too low or both causing you to tune it fatter to keep it from getting too hot or to run on after it gets hot. One other problem is how you drive after the pit stop. After fueling like above mentioned get the fuel guy to hold the buggy up and give it a good burst of throttle, then for the next lapt try not to take it too easy, the fuel is cold and the engine is hot, so try not to let all the way off the throttle and pin it for one lap after pitstops to get things warmed back up.
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Old 05-21-2012, 01:38 AM
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I to had a similar issue from time to time. To rich a bottom end.......
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Old 05-21-2012, 09:44 AM
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Also, if your pit man is filling your tank all the way to the top of the neck, when the lid is snapped shut it can force extra fuel into the carb. If you're using a fuel gun, it will help if this is the case.
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Old 05-21-2012, 11:14 AM
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Originally Posted by merdith6 View Post
One of the most common issues is it's too rich on the bottom. Try opening up the top end and lean the bottom a little and if needed raise the idle a little bit. It's not uncommon to run a little lean on the bottom during a race, and trying to tune it down to idle perfectly will only leave you flamed. Some engines I've tuned for friends i found the idle screw wasn't even touching the slide in the carb, but it could be tons of things. weak clutch springs, the engine is just a pain in the butt, I find that some really fast engines seem to load up on fuel after stops, don't know why, but its happened to me before. The tank could be a problem, but usually not unless it's beat to shreds. The glowplug could be too hot for the engine and it's getting fried quickly, really common. Or the the head is shimmed too high, or the nitro content is too high or the oil content is too low or both causing you to tune it fatter to keep it from getting too hot or to run on after it gets hot. One other problem is how you drive after the pit stop. After fueling like above mentioned get the fuel guy to hold the buggy up and give it a good burst of throttle, then for the next lapt try not to take it too easy, the fuel is cold and the engine is hot, so try not to let all the way off the throttle and pin it for one lap after pitstops to get things warmed back up.
Do you think 20 odd seconds into the lap after your stop it would still be a rich lsn? As the first thing I thought of was the common problem of the lsn but when i mentioned to one of the guys it was that far into the next lap, he said a rich lsn normally shows up straight after pitting.
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Old 05-21-2012, 12:48 PM
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Originally Posted by Nitro Tiger View Post
Do you think 20 odd seconds into the lap after your stop it would still be a rich lsn? As the first thing I thought of was the common problem of the lsn but when i mentioned to one of the guys it was that far into the next lap, he said a rich lsn normally shows up straight after pitting.
Sometimes when pitting and pushing mileage to the limits past where there is only fuel left in the line and fuel filter it will cause an air pocket between existing fuel in tank and newfuel added , food for thought
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Old 05-21-2012, 02:00 PM
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Originally Posted by houston View Post
Sometimes when pitting and pushing mileage to the limits past where there is only fuel left in the line and fuel filter it will cause an air pocket between existing fuel in tank and newfuel added , food for thought
Cheers Monty, definitely something to think about.
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Old 05-21-2012, 02:23 PM
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A longer pressure line can help a little too.
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