fuel tank / gas line issue

Moisstink

Moisstink

New Member
I know this is going to be an obvious fix but I cannot see it. I am new on the motorized bike scene and not a mechanic. What is happening is that I built a cruiser and finished it last week. I rode the bike for about an hour and a half the first day no problems. About two hours into the next day’s riding I thought I ran out of gas but the gas is not flowing from the tank to carb correctly (The line will be full of gas one second and empty the next.) I filled the tank, checked the fuel valve to make sure it was open the fuel line is below the tank and the same problem. I can see the line fill with fuel but after about five min some kind of vacuum effect is draining the line. I cannot see a leak and for the life of me cannot figure out the issue any ideas would be a help. Can the tank or carb cause some kind of pressure that will push the gas back up in the line, I do not see any kind of major leak). This has only become worse every time I ride. Shorter distances and the engine dies with the empty gas line.:-||
 
It sound like a faulty gas cap ,drill a very small hole it the top of cap so it can vent. Try this first, loosen the gas cap all the way and ride to see if that works then, if so drill the hole.
 
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Thanks for the heads up. I thought it may be something like that. I was just not sure if something in the way the carb works that could cause some thing like that considering no fuel pump. I will try them both and let ya know how it turns out. May be the weekend before I can get to it. I do have a new used gas tank (I found on here from another poster, very cool that this site has that as well) coming in the mail which is the keg style from a go cart (I believe) which may solve the problem too if that one works out. I am just not one for the tear drop gas tank.
 
ok, first off call me bean..nice to meet yall; i have read a lot of your posts 2door among a list of others and have found everything that fits my needs..i still lack in some areas so here goes..bikes got bout 200+miles (flying horse 66/80 cc motor with nt carb)..rode with a broken throttle handle for a few months now i have a new throttle handle and now have a problem with fuel(i suspect)..no gas seems to be coming out of my line right below the petcock..when i took the petcock off there was trash blocking the hole.. i then cleaned out the tank with what i had(bb's and detergent) put it all back together, got a new inline filter, checked the carb(still looks new, blew out the fuel line jet thing and gas was in the bowl bout a little over halfway) and cleaned the filter...my problem is i cant get it to go over like 7 mph..no erratic throttling rpm noises..it goes and it idles fine but as soon as i twist on the throttle its bog time.. my spark plugs(used 5, 6, and now 7 ngkbhs) have been black as can be since a couple weeks and they go as soon as i install em..anyways, so i took off my gas tank again, took off petcock again(dint see anything) put it back on..fresh gas and same thing as before. my filter doesnt fill up full of gas like it was when i took the old one off and i also took the line off at the petcock and tried that and it comes out...not a full flow but as soon as i put the line back on i see no flow..any suggestions would be appreciated and thanks again for all your help on these posts..goin to put a new fuel line on and see if that works..i also checked the petcock by blowing through it with it closed and open and it did as it was supposed to..
 
the fine-mesh filter in the tank often prevents air from leaving the fuel line, so the line and filter look empty - just unhook from the carb and watch to see if fuel is flowing

if it really bothers you, unhook at the tank just a tiny bit to let the air out
 
so, i put on the new fuel line and nothin..took my petcock off again(and gas tank) to see if there was any paint chips or rust blocking the valve and nothin..took it apart and nothin in there neither..blew through it again and it works on and off..took my float bowl off the carb and float was full and everything functioned..it doesnt seem to even trickle out into the line to hit the filter and my filters not even a 1/4th full..everything is tightened and im gonna go crazy trying to find out what it is..when it comes to engine and inside parts im not very familiar but can get a fair picture of how to..any help would be appreciated..to clarify again..starts fine, idles fine, soon as you twist the throttle its bogging and isnt goin any faster than 7 or 8 mph..now it looks like im not gettin fuel through the line even though the bowls full..thanks guys:-||
 
i did drill a hole in the cap when i first got it cause it was vapor locking. after a night of easy thinkin i am not any closer to a solution..ok..my tank never had a mesh screen in it (which i never noticed or thought of) to block the crap goin into the petcock..so my question is why, after taking the petcock off twice and seein nothing obstructing the hole, is there no flow and still trickling out? i am not an engineer but to me it seems like the petcock is the problem even though it works when i blow through it..regardless, my float stays full, but have only 1/4 gas in the bottom of the filter and i dont see nothing comin out from the petcock. ive tightened all the bolts on the entire bike(as i looked at other posts when talkin about the carb functions). i guess i need to be slapped with a Sense stick cause i feel like im missin something..only thing i havent done is rejetting and all that cause i didnt want to mess up anything since my bike is my daily ride..8 miles a day..i pedaled for this for a year and a half at 5 am..definitely dont wanna this year as i got used to cruisinbrnot thanks for all your help, nothing will be overlooked
 
I'd stop looking at the filter & begin with that fact that you need a flow of fuel to run no matter what the filter is doing. Try taking the drain screw out of the bowl and watch the fuel run out of the carb - these motors just sip a bit of fuel, so if you see a steady flow (even if it seems slight) you're probably getting plenty to run on.

The bogging could be caused by many other things.
 
ok, so i took the petcock off, straightlined the hose into tank and wallah, gas filled up in my line and filter so i went to autozone and got a valve for a mower(which is the 2 nipple sides) and got a brass fitting and put it all together..got gas in line and filter is almost full of gas..took her out and ran a lil better then once it got warmed up same deal.. i thought of my spark plug wire so i grabbed a 7mm bosch ignition plug and then i went back out. It sounded really good and had a nice idle but still wouldnt go more than 5 mph..then it seemed like my motor was a little hot (brand new ngk5bhs and i used that one successfully before) and then i start losing that 5 mph..i still am shaking my head wondering why i dont seem to be getting power..also i started out with a 24 1 but for the last 5 months 32 1..the bike was running fine till i broke the throttle handle and used it like that. i wanted it to "work right" so i switched out throttle handles and cables and since then i havnt had it runnin right ..goin through spark plugs like candy..put a 7 in the other day (startin to get bout 60's) and it was black like it was too rich but i even cut down to 40 to 1 once all this happened to me and same problems all around
 
ok, so what would these other bogging issues be..when i got the bike warmed up i almost thought i could hear air squeaking a little but wasnt sure..it happened when i would rev it trying to get it to go..so i must be getting fuel then..would exhaust pipe have anything to do with anything? i still got all the old gaskets on the ports and head and have never took any of em off. i just wanted to go to work and back..now im starting to get involved in it thanks for replying..i go nuts trying to find an answer on here sometimeslaff
 
Have you confirmed that your throttle is working? Have you actually checked to see that the new cable/throttle you installed is opening the carburetor barrel/slide all the way?

Sounds to me like you don't have the throttle adjusted correctly. When you twist the throttle grip the carb slide should lift completely. Is it?

Remove the air cleaner and look down the throat of the carb as you twist the throttle. Does the slide/barrel move upward completely opening the throat of the carb?

Also is the choke open?

Tom
 
. I still have the bogging issue..now its broken in at 200+ and never had an issue with the throttle until it broke at the j-bar adjustment and i just got lazy and tried to jimmyrig it and ran it like that until i noticed a loss of power after a while and started goin through spark plugs..on the same mix (which is actually a little richer than 32 1)i had been using which ran the bike fine... 2door.. i (after total loss of acceleration over pedal speed while the bike has started this entire time and no issues with idle..no crazy rev ups or nothing..) decide to take apart everything one at a time per you and others directions and find crap in my petcock clean it, take my carb apart(which wasnt necessary but got me familiar) and seal it back up, change plug wire again(which seemed to work better than the other one i switched out) and gas is flowing and i have spark..still no acceleration but now i have smoke comin out of pipe where i didnt before using same mix since beginning..maybe its 24;1.. regardless, bike ran fine before. the only things i havent checked are exhaust or head gasket but just wondering if it could be just running rich thanks for all your help guys.. oh , forgot that slide is in right way and it moves up and down (which, i notice is a reoccuring problem when people get that runaway throttle upon startup) and just an off question, how much fuel is supposed to be in your carb bowl? mines full but i looked at those tangs on the pin for the fuel line and decided against trying to craft a swan or something haha
 
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