No gas to engine- what the heck is going on?

[Lucien Harpress]

Remember what I said about crying "victory" too soon?

Yeah. More issues popping up. Unless I completely flood the carbs (and I KNOW there's enough gas in it), it runs really rough and drops cylinders, which one depending on the day.

More than likely it's a issue with the float needles. First, there's a clear section in my fuel lines right before the carbs- gas is getting through here, so lines aren't the issue (anymore). It WILL run fine when the carbs are full. I already have suspicions that I buggered up the float needles anyway, so I figure in any case replacing them is a good idea.

Over at mikesxs.com, are the float needles offered there (Part #48-5014) the ones I need? They look the same, but I want to be sure things like size and diameter are what I need.

[dbeardslee]

Lucien - Those are the correct float needles for 80/81 carbs.

[Lucien Harpress]

Okay, my problem is DEFINTELY fuel line/petcock related. If the carbs are saturated to the point of being closed up, the bike runs like a dream. Once that gas in the lines is gone, though, she doesn't run so happy anymore. The way I figure, I either have an air bubble in the lines or it's getting kinked somewhere. Whatever the case, the gas is simply not getting from the tank to the carbs.

The bad news is I still don't know EXACTLY what's wrong. The good news is that I'm (hopefully) finally finished pulling the carbs off my bike. After 4 times, I don't want to ever have to do it again.

[Crazcnuk]

Forgive me if this has been asked before, but have you checked the screens on the petcocks themselves? Flow wise, I mean, they may look ok, but if they have build up on them they may not be flowing enough fuel?

Someone here may know what the flow rate should be, so you could test the petcocks without taking them off. Just time for a minute and see how much gas comes out?

[Lucien Harpress]

Unless there's a screen I can't see (one different from the big plastic one sticking out from the top of it), it looks clear. I guess I could look inside 'em and see if there's gunk built up in there, but I've never done that before, so I wouldn't know what to look for.

It isn't really a big deal taking them off, though. After yanking those carbs so many times, petcock removal is a breeze!

[oseaghdha]

Lookit

You said you added filters. What sort of filters are they? You say it ran sort of ok then crapped out. Are the filters clogged up?

Can you run fuel freely thru them? I mean, can you remove the line after the filter and set it to PRIME and have fuel gushing out of the line?

What about the carb vents? Are they clear and routed correctly?

Not sure how you are filling the lines and carbs to make it go. Does the petcock itself flow freely when the line is removed?

Are you trying to run it with the petcock set to PRIME?

Can you post a picture of the fuel line routing?

[DGXSER]

Ventilation!!

As stated, I would start by pulling the fuel line from the carb and putting it into a small can or something and see if fuel flows. If it does then it is the vent in your carb bowl that is plugged.

Another vent to look at is the tank vent. If air can not get into the tank, fuel will not flow out. The vent is in the gas cap. When it starts crapping out on you, try running it with the cap open and see what happens

[Lucien Harpress]

Alright, a couple answers, then a question or two.

- Fuel filters were simple in-line units bought at my local Tractor Supply. When I looked at them this last time there was a bit of crud in them, but not enough to clog them up.

- Fuel running through the lines was the next thing I was going to check. I'll do that tomorrow.

- Carb vents: HERE may be an issue, because I've never heard of these before. What are they, and where are they supposed to go to work correctly?

- Nearly all my tests have been done with the petcocks set to PRIME.

- Fuel routing is identical to that shown in this tip:

http://www.xs11.com/xs11-info/tech-t...l-filters.html

I'll try the tank venting procedure (with gas cap open) tomorrow as well. In addition, there's something I've been noticing- every time this problem crops up, it's always the first two cylinders that drop off first. This leads me to believe it's a problem with the routing of that line, or a problem with that petcock (Because each fuel line splits off into the two adjacent carbs). However, like I've said before, it may be a problem with the carb vents, because I have no idea what these are, and I may have inadvertently clogged them at some point.

(Also, to fill the lines to the carbs, I used a small funnel fitted to the end of each fuel line. Using this, I can pour small amounts of fuel into the line until the float needles seal off the carb and fill up the line).

[DGXSER]

Carb vents: HERE may be an issue, because I've never heard of these before. What are they, and where are they supposed to go to work correctly?

On your bike, being the newer carbs most likely, the vent is built into the inlet bell of the carb. The older style carbs had a separate T on the carbs, above the fuel line T, that vented the bowls and the line in stock formation ran to the air box.

[dbeardslee]

Lucien - If your carb vents are plugged it will cause gas to run out the carb bell. It won't stop it from flowing. What kind of fuel line do you have, the black automotive or the yellow lawn mower stuff? Did you ever get rid of the viton tipped needles you said looked deformed from soaking in carb cleaner?

[Lucien Harpress]

Fuel lines are the black automotive type. And yes, all four of my float needles are replaced.

If the vents you are talking about are the large oval openings on the topside of the carb inlets, then all four should be clear.

[DiverRay]

The vents are actually one of the smaller holes in the bell, if you have 80 carbs. The '78/'79 carbs have a second "T" above the fuel "T" for venting to outside air. This will plug into nipples on the airbox. The 80 airbox does NOT have holes in the nipples, so it will NOT vent the early carbs.
The fuel line routing sounds like part of the problem. I run my Standard with the fuel lines crossing. The left petcock feeds carbs 3&4, and the right petcock feeds 1&2. This keeps the lines from kinking as you put the tank back on.
You will also need to check the vacuum line, and the vacuum on the petcocks. If you have a vacuum pump with a gauge, you can use that to check the petcocks.
The fuel lines CAN kink and cause problems, so that is the first thing I would check. The filters on the petcocks can be cleaned with spray carb cleaner to verify there are no problems there.

[mason79]

sorry i didn't read all of the posts, but i had a fueling prob for a year and a half, it got better after i cleaned the gas cap vent and the entire gas cap i took apart, but it was not enough.

what it was, was the paper fuel filter, would dry out when the gas would evaporated from the bowls from my not riding the bike enough( they are vented to the air cleaner, I have a 79f), this drying out would along with the crap, varnish and whatever was around the paper cone would seal the filter shut, sure i got it to crank and fire but it would stall like heck and who knows what i did to my bearings with all those hard starts.

#4 the one near the right leg would always not run, that's because my bike had been on the side stand mostly and perhaps it had drained away to the other carbs over time

I would get it running, my guess the new gas would soak off some of the sealing, over time.

I looked at the paper element closely while it was not aweful as with the first few changes, it wss not clean by any measure.

I swapped it out to a mesh filter and and a gel battery and i start everytime without a hitch.

and the bike runs better as well since it's getting the fuel it needs, that's just my fueling problem, perhaps not yours but it was mine....

[oseaghdha]

Can you run it with the tank jacked up so you can visually verify all the lines are free and unkinked? Like when you would do a synch job.

I tried that particular routing, but didn't like how the lines go across the airbox boots. When I dropped the tank into place, they got mashed up.

But I have a Special, and the nipple points downward, rather than sideways. YMMV.

Sorry about the vent thing, I didn't pay attention to the year.

[thewiz]

Here's a link to a thread with a pic ...

from Rob Hanna that is the way I also route my fuel hoses. Only difference is that I put MikesXS clear fuel filters at the bottoms of the loops so I can see and change 'em pretty easily
http://www.xs11.com/forum/showthread.php?t=18799