Problem switching to reserve

[VodkaAndPickles]

So soon after I switch to reserve, the bike runs out of gas.  Now I know there are about 2 more gallons left in the tank, so it must be a flow or petcock problem.  This only started happening recently; before, I could easily get 280 miles on a full tank.  I do run a NAPA filter, but as I said I haven't had the problem with it before.

The petcock does leave a drop of gas on my gloves when I operate it.  Is that the problem, most likely? 

[snarf]

The way I understand our tank, its 7.5 gal, about 5gal before reserve, and about one gal of the reserve is actually used.
what is "soon after reserve"?
I would order a petcock rebuild kit from Murph asap. It might be a good time to look into a Pingle. It sounsd like the oring in your petcock is dried out/dinged up. You may be able to get by with taking it apart and inspect the oring. Put some good oring grease on it; I use Molycoat. Personally I would rebuild.

[Summit670]

I just took the NAPA filter off my bike because it was unreliable as to how far I could drive on reserve.  The filter has been on 2 years and it is clean anyhow, plus the bike is an 87 with 73,000 miles and has lived this long with no filter.  The carbs have never been plugged or the needle valves stuck because of grit.

Now, my tank is coated with POR 15 and has been for 15 years or so.  I also recommend draining the float bowls at least 2x per year to flush out sediment.

On the leaky petcock - I think you can "swell" the o-ring a little by soaking it in brake fluid, Dot 3, but don't quote me on that.  I don't know how long it would need to soak either.  I'd try a few minutes and go from there.

[Mettler1]

  I have to say the last time I moved my petcock was about 14 yrs ago. I don't count on reserve and I'm usually ready for a stop at about 220 miles. When I take my tank off and no gas leaks out I'm happy.

   Although I may replace the old petcock this spring. It's 18 yrs old!!

[VodkaAndPickles]

The way I understand our tank, its 7.5 gal, about 5gal before reserve, and about one gal of the reserve is actually used.
what is "soon after reserve"?
I would order a petcock rebuild kit from Murph asap. It might be a good time to look into a Pingle. It sounsd like the oring in your petcock is dried out/dinged up. You may be able to get by with taking it apart and inspect the oring. Put some good oring grease on it; I use Molycoat. Personally I would rebuild.

Last time this happened, I switched to reserve at around 180 miles.  At 190 miles the bike died.  I know from previous experience that reserve is realistically not 1, but 2 - 2.5 gallons, and should last somewhere around 80 more miles.

Another time I switched to reserve and it simply refused to catch.  The bike died on me at night in the middle of heavy traffic on the highway right outside the Lincoln Tunnel in NYC.  It didn't even work long enough for me to pull over onto the shoulder.  There I was, stopped in the dark like an idiot with my hazards on trying to restart the bike.  I almost got run down from behind by a semi.  Had to push it over to the shoulder and rock the bike back and forth some, eventually it started feeding gas again.

[Mettler1]

Last time this happened, I switched to reserve at around 180 miles.  At 190 miles the bike died.  I know from previous experience that reserve is realistically not 1, but 2 - 2.5 gallons, and should last somewhere around 80 more miles.

Another time I switched to reserve and it simply refused to catch.  The bike died on me at night in the middle of heavy traffic on the highway right outside the Lincoln Tunnel in NYC.  It didn't even work long enough for me to pull over onto the shoulder.  There I was, stopped in the dark like an idiot with my hazards on trying to restart the bike.  I almost got run down from behind by a semi.  Had to push it over to the shoulder and rock the bike back and forth some, eventually it started feeding gas again.

     WOW, that's what I call a real problem!!!   Hope you find the cause. Let us know if you find it.

[Summit670]

My theory on the filter is - if you wait till you run out of fuel in the primary position (keep it clean guys) then after you change to reserve the fuel has to fill the filter as well and there may be a big air bubble in the filter.

Maybe this has been done, but has someone tested how far down fuel will feed  if the tank is switched to reserve before you actually need it?  After being stalled on the side of a 4 lane residential street after switching to reserve I made it a point to switch to reserve around 220 miles, before the bike died.  That was last year.  As I said, I just removed my filter last weekend after I went thru the carbs.

[VodkaAndPickles]

Does the prime position flow fuel when the fuel tank has dropped down to reserve?  I tried switching it to prime also, just in case there was an air bubble there somewhere.  Didn't help.

[VodkaAndPickles]

Maybe this has been done, but has someone tested how far down fuel will feed  if the tank is switched to reserve before you actually need it? 

The most I've ever gotten on a tank was somewhere around 290 miles.  There was still some fuel left, I think.

I switch to reserve when the bike starts sputtering.  That way I know more or less how much fuel I still have left according to the odometer.  Always worked before.

[Cholla]

It sounds as if either sediment is blocking the flow at low fuel levels, the petcock screen is dirty or both. Remove the petcock and check the screen first before throwing money at it.

[mjrfd99]

It sounds as if either sediment is blocking the flow at low fuel levels, the petcock screen is dirty or both. Remove the petcock and check the screen first before throwing money at it.

+1 Great answer! and while your at it soak it in some WD-40 to lube it a little

[Furbo]

+1 Great answer! and while your at it soak it in some WD-40 to lube it a little

I'd rebuild your petcock if it were my bike. A leaky petcock is to hydrolock as sex is to babies: while the existence of the first doesnt always result in the second, the occurance of the second virtually always presupposes the first. 

[VodkaAndPickles]

I'll try to at least start stripping the bike down this weekend.  The bike has also developed a coolant leak, so I'll have to fix that also.

 I'm REALLY f*cking busy right now, so this is the last thing I need.

[Boomer]

Prime takes it's feed from the reserve intake. which is just a hole in the petcock casting.
The main feed is from a tube.

If it's not flowing in Prime but runs fine on Main then it sounds like yer reserve feed is blocked.
The petcock is easy to remove and take apart.

Remove the tank from the bike.
Empty most of the gas from the tank.
Put the tank on a towel on it's side.
Unscrew the 2 bolts and remove the petcock.

There should be a plastic and mesh shroud fitted over the tube.


Inspect the mesh for any tears or splits.
If it's OK, put a hose on the fuel fitting, set the petcock to Prime and blow in the tube.
Any crud in the system should get blown out into the shroud.
If there was crud, then I HIGHLY recommend buying a new petcock.
The rebuild kits are crap and usually fail after a few months.
A new Petcock will give years of problem free operation.
Murph sells 'em for $73 http://www.murphskits.com/catalog/product_info.php?cPath=1_94&products_id=140

[bbroj]

It sounds as if either sediment is blocking the flow at low fuel levels, the petcock screen is dirty or both. Remove the petcock and check the screen first before throwing money at it.

+1