Air bubbles in my fuel filter

I believe I have a vent issue with my '85 miniceptor. After about 30 min of riding it starts to run out of gas when it shouldn't and i've noticed quite a few air bubbles in my fuel filter coming from the tank. The fuel pump is deleted and has been for 3 years without a problem. I recently put an '86 motor in it and rode it for the last month without incident and since it has been in the 60's and 70's it has been doing this.

The only thing i can think of is that there might be a hole in my fuel line? I dont understand where the bubbles would be coming from.

Has anyone experienced this before?

 

It sounds like your diagram is damaged.

It could have a tiny sized pin hole leak, which would allow the fuel, once flowing, to suck some air through the line.

Also, check to make sure your fuel line is nice and tight on the petcock side.
Cause if it isn't, it'll suck air and you won't notice this because fuel won't come on out of that area.

The fuel will just keep flowing down.

But it sounds like your starving your carbs from fuel....look into that problem first.

And make sure you have a fuel tank when you do any tests:thumbsup:

:biggrin:

 

Did you have any resolution to this issue?

I have intermittent issues (on my '86 vfr700) where it seems like the bike runs out of gas and is hard to start (probably has to push all the air through). Whenever this happens, the fuel filter is empty. If I take off the fuel line, it gushes like a garden hose...

Ten minutes after I stop, the fuel filter might be almost entirely empty... then I come back in an hour and it is full of fuel.

Air has to be getting in somewhere. Also, it doesn't seem to be as likely to do it when the fuel tank is full.

I think the petcock was replaced by the P/O last year. Mostly new rubber hoses as I replaced the fuel pump while troubleshooting the issue. I could put on all new hoses and make sure they are well tightened.

Any other suggestions? Is there any risk with the gas tank vent or anything like that of introducing air?

 

I had the same problem on my babyceptor when I got it, not long after it started I noticed it started to idle kinda weird. Was pulling the tank to get to the carbs and the vacume line was full of fuel. Replaced the diaphragm and no more problems. I'd pull the vacume line and make sure it shows no signs of fuel first then check the fuel line. Also if you have one of those glass filters they do not seal very well at all, or at least the ones I've used haven't

 

forgive my ignorance about this... i just got the bike and have hardly opened it up.. is there a vacuum line going to the tank? or is it to the petcock to make it so gas only flows when there is engine vacuum?

what does fuel in the vacuum line indicate?

like i said - i think the petcock was replaced so that would have the diaphragm if it's part of the petcock

 

Sorry, I'd been up about 22 hours when I posted before, they joys of being a cop. The vacume line should go to the petcock to operate the diaphram that shuts fuel off when there is no engine vacume. When putting the vacume line back on though there are two nipples, one of them is for the vacume line and the other is a vent for the little system and I can't remember which one is which at the moment. Also fuel in the vacume line will just show that the diaphragm is is leaking. If I remember correctly it is also possible for it to be leaking but not get into the vacume line, in that case there should be a little fuel at the vent nipple. Even if the petcock was replaced that doesn't mean it was done right, take nothing for granted when it's someone elses work. They may have been patching it up to pawn it off.

 

the hose was really loose where it hits the fuel tank! I could yank it straight off. A fresh hose and hose clamp seems to have fixed the issue!

after all of that, on my way home tonight, the headlights got dim and I found the battery was dead. haha. so looks like i might be r/r-ing it up!