i hate chasing gremlins

[v4intn]

So on a 2002 Magna, freshly rebuilt carbs, running sync done, tank was "creemed" and i'm stumped. this thing will run like a beast for 5-8 miles... then spits and sputters like its starving for gas and dies. i'm thinking either a bad diaphragm in the annoying auto fuel shut off valve or the in tank filter, those are the only things i can think of that would restrict fuel flow to the point of shut off, but may be fine after sitting for a minute. and by may i mean sometimes it fires up after a minute, sometimes its a bear to start back. anyone had a similar issue? recently got this bike with 8000 miles, it sat in a garage for 10 years so i had everything professionally cleaned, carbs rebuilt, tank treated, and it ran like a champ for about 150 miles now this

[lragan]

An easy thing to check is the vent tube.  Simple way to check it is to open the tank when it dies by simply removing the cap.  If it sucks air, then it is not being vented.

Hope this is the problem.  You should be so lucky...

[v4intn]

didn't hear any hissing when i opened it ( thought of that lol ) and in about a 20 mile trip earlier today for a road test it literally died 5 times. was going to check and make sure there was fuel in the carb bowls but somehow i left the screwdriver out of the tool kit... BUT its also possible the vent tube is pinched and letting it vent but not enough for sustained running, it is the rubber line from under the tank to near the back wheel isnt it? ive fixed many bikes but ive honestly never seen one with some of the oddities ive found on this one

[ttooee]

I think the auto shut off valve is a seperate valve on the right side of the bike. The switch attached to the tank is just a 3 way switch. I assumed that you have this problem even when this switch is on reserve.
I once had a problem and I thought it was the carbs or the timing, but it turn out to be the RR. So now when I have a problem like this I would disconnect the RR and run on strictly on battery and see if the problem persists.

[v4intn]

Yeah the auto shut off is on the right hand just under the tank, the standard 3 way petcock is on the left. Ive checked the voltage, but not after running it for a few minutes, so heating up the RR would explain when it shuts off. What has kept me from checking the electrical more in depth is the battery charges normally and I havent had to charge it since I got the bike. Ill put it on a trickle just to be 100% its fully charged and give it a shot. Ive made an hr trip on a shadow with a bad stator and good battery, so  unhooking the charging system should let me get farther than I have been if thats the issue

[ttooee]

If you do this during the day, I would pull the head light fuse to conserve battery.

[v4intn]

So its not the RR, unhoojed the rectifier and pulled the fuse and got the same thing it's been doing. So almost definitely sonething restricting fuel flow to just a trickle. Thinking maybe the "professional" that did my tank and carbs didnt change the in tank filter, either that or the auto fuel shut off is going out.  Atm im thinking more likely the filter since everything ive read says I would smell gass if it was the shut off

[hop along]

OK-one question-when the tank was Kreemed (by that I understand you sealed the inside of the tank with a liquid sealing liner), did you run low pressure air backwards through the vent tube connection?

If not, it is possible to seal the 2 little holes in the vent chamber which is inside the tank. 

Yes, I've already done this.... this is why I posit this as a potential cause of the problem. 

If it were me, I would do what I did last time:
1-make sure the vent tube isn't somehow pinched or blocked (it could be plugged with grime at the bottom end for example).  Easy thing to do: remove the vent tube for a brief run to see if the problem persists.

2-IF problem persists, drain as much as possible and remove tank from the bike.  Remove the gas cap.  Provide light air pressure backwards, into where the vent tube connects.  (I blew into it by sealing my lips around it... not recommended!  But I got the tactile feel I wanted).  If air doesn't blow through (mine didn't) then you can be sure the 2 little holes in the vent chamber are sealed, or the vent tube itself (which is easily a foot long inside the tank) is sealed.

3-I tried and tried and tried to clear things up by putting solvents backwards through the vent tube.  Utter failure.  Tank liner had to be cleaned out with acids and re-lined, correctly, with reverse light airflow through the vent line to prevent from happening again.  My vent chamber was sealed so bad the front had to be cut open, things cleaned up, rewelded, and then resealed properly.  Luckily for my patience I had taken it to a radiator shop that specializes in motorcycle tank sealing so it was *their* problem to deal with.  Also luckily, I have a valkna tank and don't care what it looks like.  It holds gas better than I do!!

I think I posted a thread along these lines, I will look for it in the forum and report back if I find it.

Good luck.  Let us know what you find.
Hop Along

[v4intn]

Thats another good possibility. Ill check the vent tube as soon as a friend brings me his gas can (my 1 gallon is useless for draining anything) need to get this rolling as quickly as possible now since my other bike dropped a shift pin, a V4 classic that I didnt know had that issue till it happened lol

[hop along]

http://www.magnaownersoftexas.com/forums/index.php/topic,5413.0.html
That was the thread I started when I first messed up.  I didn't report back to that thread once I took the tank to the shop-all the shop stuff was after this thread. 
IF you determine this is your problem, Its a headache and not solved quickly unless you can strip the liner, cut, reweld and reseal the tank yourself.

The thoughts voicing the fuel filter are also valid.  You'll still need to drain and remove the tank in that instance to remove the fuel filter (it should come out when you remove the petcock).  But I suspect when you drain the tank you'll get the impression if it is the fuel filter or not.
IE-if you remove the gas cap, THEN drain through the petcock (attach a hose from petcock to a gas can) it should either drain quickly or trickle.  If its quick, the fuel filter is probably ok.  If its slow, suspect the filter for sure!
--If you leave the gas cap on, drain it and watch the rate of flow-if it starts fast, then slows over time, the filter and and the vent system are both culprits.  If you then remove the gas cap and it immediately speeds up, the filter can probably be eliminated as suspect, and the vent system is more likely the culprit-but you'll be there with the tank removed to look into that so I'd inspect the filter anyways.  Its cheap, quick, and easy compared to the vent system.

Good luck.
Hop Along

[v4intn]

I saw where someone (don't remember who or where) recommended venting the cap by drilling a pin hole in the bottom. Good idea or not to bypass the vent hose if it its stopped up internally?

[v4intn]

Do since its a cheap part if I ruin it, I drilled 2 1/8th inch holes in the underside of the cap and cut 1/4inch out of the gasket and road tested it. I was HARD on the throttle and it ran like a champ, doing a better road test than 20 minutes tomorrow with my fingers crossed. Thanks for the help guys and if theres anything else weird (like the tank vent being under the tank lol) I may need to know ahead feel free to warn me

[Jerry G Turner]

The auto shut off valve will cause the issue you discribe just by pass it and see if this solves your problem.

[v4intn]

Thanks Jerry, I havent trusted that thing since day one lol. I may bypass it anyway so it doesnt cause a problem. That just seems like a good place for an inline filter and since I dont know if the guy that redid the tank used an ethanol friendly filter I may need an inline eventually

[MagnaMan]

Sounds like you got it figured out.

I personally stay away from the tank cremes. A few years back I flushed my tank with a non-toxic rust remover and got out a ton of rust. Supposedly this rust remover doesn't etch the metal. So I just filled the tank back up with gas and I've been running it that way ever since and I can't say that I've seen any of the rust return.

In my experience if the auto shut off goes bad it will leak fuel out of a weep hole on the bottom of the unit... However, I have heard of others who did not get the leak but experienced similar symptoms to what you were describing before you found the venting issue.