Irratic dying

[L-]

'01 FLHR, DTT ignition, stock petcock and Mikuni carb.  With a 1/2 tank of gas or less it will sputter then quit running at 110 mph. back off the throttle a little bit and it starts back up. Has not done it with a full tank of gas or when it is cool in the morning whether cool or hot. Could this be a vacuum problem with the petcock or ................?  It just started doing this a few weeks ago and nothing has been altered on the bike in a few years either.

L-

[MaxxV4]

Gas cap venting issue?
Mike

[hotroadking]

check the vac line for cracks or breaks
also the petcock could be fouled might need to be cleaned
put it on reserve see if it happens

You might want to run a pingle non vac fuel petcock if you have to replace the stock one...

[L-]

Forgot to say I have tried with cap loose and just taped down. I have a petcock but have just never got around to put it on.

[RVGRG]

How many miles are on the bike?
Had something similar to this happen to mine recently. Not allways but on occasion when running somewhat hard for extended periods it would seem to run out of gas for lack of a better term, even if I switched over to reserve. Bike would die and then restart by the time I gave it the once over. Tried riding with cap loose, checked for tank venting, cleaned tank vent valve, tore into the petcock a few times just could not figure it out. Finally pulled the vent line off of the charcol canister to check it and WAALA, that was it. Canister was clogged. Vented gas tank to the ground and have not had the problem since.

[FLTRI]

Sounds like the old running the float bowl dry thing.
Long durations @ high rpms/speeds. (110mph)
The stock petcock will not flow enough if you have a built engine (a stock engine will not make a FLHR go 110mph).
Bob

[L-]

110 by the speedo, but close enough. 95 inch 100hp/107tq.  Short run, 50-60 mph then open it up for about  a mile.  It is very similar to running out of gas and then turning the petcock on.  So, doesn't sound like the DTT or fire?

L-

[FLTRI]

Gotta love those carbs.
Full tank = more pressure = higher float level maintenance during WOT.
1/2 tank = less pressure = lower float level maintenance during WOT.
Bottom line = need more supply = bigger petcock.
Bob

[RVGRG]

If this only happens at WOT then I think Bob is correct. If it happens during regular sustained riding then check into the tank venting system, from gas cap to canister.

[L-]

The bike is about nine years old with 84,000+ miles on it.  It never has done this before.  It has done many trips through the desert loaded down at this speed an a little higher for up close to 60 mile jaunts.  Well, the weekend is here and I will check it out. Thanks,

L-

[BikerJim44]

L, If you have a vacuum pump like for bleeding brakes  put the catch canister in line and then attach to your vacuum nipple at the petcock. Pump it just enough to open the diaphram and see if you get any fuel coming from the vacuum on the petcock, even a drip would mean the diaphram is shot and you need to replace the petcock. Spidey.

[FLTRI]

'01 FLHR, DTT ignition, stock petcock and Mikuni carb.  With a 1/2 tank of gas or less it will sputter then quit running at 110 mph. back off the throttle a little bit and it starts back up. Has not done it with a full tank of gas or when it is cool in the morning whether cool or hot. Could this be a vacuum problem with the petcock or ................?  It just started doing this a few weeks ago and nothing has been altered on the bike in a few years either.

L-

Sorry L, thought this was an ongoing problem. I didn't realize the bike worked just fine for many miles, then the symptom started all of a sudden.
You may want to see if the internal petcock filter is getting covered with tank sediment or even inner tank paint.
Also check the flow by removing to fuel line @ the carb and let it flow to see if it continues at a good rate.
Bob

[Jeffd]

at 84,000 I betting petcock screen is getting covered with slime.  I just pulled mine and put on a Pingle, now I just need to remember to shut it off and turn it back on.  Mine was at 70,000 and screen looked pretty good but it did have a little slime on it.

[BikerJim44]

You can also get a replacement screen. The other thing I was thinking about too is that you may want to look down into the tank and make sure the lining is not coming lose and clogging the petcock screen. I have seen several of the older bikes lately where the tank lining was peeling inside and getting junk in the screen or covering it up and slowing or stopping the flow. Spidey.

[L-]

Trouble was a small hole in the diaphragm.  It got progressively worse.

L-

[FLTRI]

Trouble was a small hole in the diaphragm.  It got progressively worse.

L-

Glad you found it. Sure is a common place to suspect, however most of the time the hole is big enough to simply not open the fuel valve so the bike will not stay running after it starts from the float bowl's gas.
Not sure how the fuel level has a bearing on the operation of the valve, but it's fixed and that's the most important thing.
Bob