dr15144
RCTalk Basher
ok as i try to start my truck i start seeing air going back to the tank and the gas going to the tank as well..... WTF? can't figure this one out any ideas on where to sart and what to do ?
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Carb pushing air to the fuel tank?
- Thread starter dr15144
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What kind of engine is it and how are you trying to start it?
dr15144
RCTalk Basher
- Thread starter
- #5
it is a brand new header and pipe on a firly new engine, i first posted in a dif area about engine not running, i done been through most of the obvious all new fuel lines and filter all the rings and gaskets but this last tim ei was messing with it i noticed that after i primed it and got the fuel to the carb and tried to start it i noticed aire and fuel going back to the tank from the carb........I'm confused as hell here
dr15144
RCTalk Basher
- Thread starter
- #7
ya I'm at the point of just throwing the damn thing out the window and running it over with the lawn mower!... think i may just try a new carb, have already tore this one down 3 times and went through it double and triple checked everything. may be the sleeve? just not causeing enough back pressure from the exhaust to push the fuel into the carb?...
Skwerly
RCTalk Addict
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Maybe you could take it down to the LHS and have it looked at quick? Most of those guys just love to do it, and rarely charge much, if anything at all! 
flandersander
Hardcore RCTalk User
well, if you're gonna destroy it, can I reccomend strapping rockets to it? Then you don't need the engine, and its bound to be destroyed, but its more satisfying than a lawn mower.
Amoeba
RCTalk Addict
You may already tried this but, have you checked your fuel tank for an air leak?
ohmygahitscoby
Hardcore RCTalk User
Did you install the fuel lines correctly?
Djbrady
RCTalk Basher
Have you gotten it to run at all?
Djbrady
RCTalk Basher
if it were a 4 stroke, I'd wonder if there was the strangely remote chance that the engine were spinning in reverse, but being a 2 stroke, I don't that would make any difference at all.
That's really strange man... wish I could offer more help.
That's really strange man... wish I could offer more help.
man, i really hope not to insult your intelligence here but take another look inside your tank at the lines in and out. Not all tanks are the same obviously but my carb side line comes out the top with an internal pick up line to bottom. yours may be the same. In either case, you describe fuel getting to your carb and air comming FROM the carb so I doubt this to be the case for you.
You could also try removing your fuel tank (or use a bottle and another line) and hold your tank above the car and start it. Use gravity as feed and check for bubble then, as well feeling pressure coming off your exhaust port to the tank.
Lastly, check your lsn settings. you said you have had tuning issues...it's possible that you just have you lsn closed to far. look closely at the carb input line when you crank with closed throttle, can you see it pulling fuel or does it look stagnant? Air may be just a result of not pulling enough at current needle settings and not the actual reason for stall. if runs at part or open throttle without shutting off, but dies when carb closes to idle, open lsn more. With everthing else you described i'd say your problem is first visually check inside of tank to verify fuel vs pressure lines...then open lsn more and see if it changes corrects the problem.
I had a self induced problem similar to this. I had no replacement filter and no safe way to clean my only existing filter. So i was constantly leaning out carb to compensate to partial choke condition. ultimately pretty much wound up closing my lsn completely and when i installed new filter, was having very similar issues. bubbles from carb side and wouldn't idle...would crank and run at part or open throttle but could not idle. after some cussing and closer examination i could see the complete halt of fuel flow at idle. I opened up more...a lot more in fact, almost two complete turns, got it to start then turned it back in to proper tune. All was well after that.
RC Addict
RCTalk VIP
+1 on a tank air leak. Check the o-ring seal around the cap, the seam where the two halves of the tank were joined together, and the fuel pickup tube inside the tank.
i've never had a seal gone on my tank ..yet, but wouldn't he have noticed a tank air leak when priming? or even made it impossible to prime? Not challenging your input by any means, just looking for more details for my own bag of tricks. The reason I mention it, I read over a similar post when i was trying to figure out what I had done to myself a while ago and saw other posts mentioning it. (yes, i looked for a similar post for answers to my problems before posting...i had the time.lol) Mine wasn't starting either and noticed complete lack of fuel moving in the line. I spent a rediculous amount of time looking for a possible blockage. (newbs) wasn't till i pulled lines off carb and exhaust and blew fuel all over everything that i started looking elsewhere.
Even still, a full tank, filled above carb level and a primed fuel line, should not have issues running just based on gravity should it? My issue turned out being, after really messing up my lsn setting and trying to guess at a rough base line (typical small engine 1-1/4 to 1-1/2 turn from full seat) was NOWHERE near out far enough. I put my ez start on, put a screw driver to the lsn and hit the button and started turning it out till she cranked. Had to go almost double what i thought my inital setting was...actually past it a little and was able to bring it back in some after starting and cleaning out some.
Either way...the situation he's describing is very similar to the symtoms i was seeing initially. As always Addict, I value your oppinion and look fwd to your feed back.
