'99 Sportster XL1200C 99% of the time will not start as of the end of last season through now. New battery last year, fully charged. New spark plugs before being stored, has spark. Gas tank drained and filled with fresh gas x3, fuel filter not clogged or torn. Carb removed, disassembled, cleaned and reinstalled. Didn't fiddle with any jets but blew through them and they were not clogged. Air/fuel mixture screw still under factory plug.
Over the past two years my starting sequence has always been fuel, choke, key, kill switch, goose the throttle 1-2 times and start. Since the issue started I can press the start button 6 times and it won't start. Sounds like it's cranking, just won't fire up. Sometimes I'll go out the next day after being frustrated and it'll fire up with one press. I can let it idle, take it for a ride and there are no issues. Shut it down, wait a minute and it won't start back up, right back to cranking. Below is a video I took of an attempted start up with the air filter removed because I wanted to make sure the carb would spray fuel when I twisted the throttle, it did. I'm kinda at a loss so any suggestions would be helpful. I'm no mechanic but I know my way around a wrench.
I didn't notice any damage to the boot the carb plugs into but I was thinking of pulling the carb again to drill out the air fuel mixture screw plug. I can recheck the boot and the manifold itself. My only hesitation about it being an air leak is when it's running, there are no issues. No lingering high rev's, not lag in throttle response, no struggling to idle and it's not running hot.
Could be the vacuum thingy on the petcock,forget what it's called but it opens and lets fuel flow from the tank then closes when the bike is shut off to prevent carb overflow etc.
Having a brainfart on what it's called but it has a vacuum activated diaphragm via a small hose from the carb.
I don't know if '99 has the vacuum actuated petcock or not.
Could be the vacuum thingy on the petcock,forget what it's called but it opens and lets fuel flow from the tank then closes when the bike is shut off to prevent carb overflow etc.
Having a brainfart on what it's called but it has a vacuum activated diaphragm via a small hose from the carb.
I don't know if '99 has the vacuum actuated petcock or not.
To check, replace vacuum hose with clear hose and watch to see if sick’s gas through it. If so, replace petcock.
Does the bike smell of raw gas like it’s flooding when you try to crank it?
'99s do have a vacuum line and I noticed the end at the petcock was a little dried out. That's something else I can look at when I pull the carb. The only reason I don't think that's the issue is I'm getting fuel when I twist the throttle, that's why I had the air filter off in the video was to make sure. There was also gas in the float bowl when I took it off.
No sir. I don't smell gas unless I've twisted the throttle and it doesn't start up.
Well then I'd be checking for spark,not sure if '99 has the VOES or not,those can be a problem and if it does there would also be a vacuum line to it.
If no spark it could be a crank position sensor gone bad or even an ignition module gone bad.
I'd be checking to see if you have spark next since you have gas,
1. Check your diaphragm to make sure it is not torn or has a hole in it.
Check the Slide Diaphragm - Be sure the slide operates correctly & the diaphragm is not torn or punctured. To do this, remove the air cleaner and reach your finger into the carb throat to the slide - push the slide up and quickly let the slide fall down. You should hear the vacuum sound as the slide returns to the bottom position.
2. Additionally, make sure your pilot jet is orientated correctly.
3. Put the petcock in the reserve postion and try and start it to see if there is any difference.
'99s do have a vacuum line and I noticed the end at the petcock was a little dried out. That's something else I can look at when I pull the carb. The only reason I don't think that's the issue is I'm getting fuel when I twist the throttle, that's why I had the air filter off in the video was to make sure. There was also gas in the float bowl when I took it off.
Oh, you’ll still get fuel when it goes bad. You’ll not only get the normal fuel, you’ll also get the fuel it sucks through the vacuum line. It’ll run like you left the choke on after it warms up. Might not be your problem, however. I wonder if you’re getting spark if it isn’t even trying to fire.
04-14-2023, 11:57 PM
'99 Sportster XL1200C Won't Start
