Fuel petcock repaired but still issues

[ktoal54]

I read a number of other posts on this subject but didn’t find anything similar. I recently replaced the diaphragm in the petcock because I was “running out of fuel on the highway”. It seemed like it solved the problem but then I had it start sputtering again but not as bad. It again only seems to happen after a few miles at highway speed. The old diaphragm definitely has worn out with holes and tears in it. I am wondering if anything else causes the same issue. It acts like it’s running out of fuel. When I get off the highway it recovers.

Thanks for any help.

[Fazer]

Others will chime in, but you might have kinked your vent line when your removed/replaced your tank.  Or, the fuel line itself may have been disrupted.  Very important that it is the length it is, not made longer to facilitate tank removal.  Also, the vacuum line that goes from your petcock to the carb bank.  If it has a slight crack or loses vacuum for any reason, it will shut off your fuel. 

[ktoal54]

Thanks Fazer. I plan to take it apart again and probably replace the vacuum hose. The fuel hose is kind of short too and is hard to connect. I think it may have shrunk in length over time. I want to make sure there isn’t something else I have overlooked before I do because taking it out for a long ride to test it may leave me with a long walk back. The diaphragm was also hard to fit like maybe it had shrunk too. I wonder if there could be a leak there also.

[The emperor has no clothes]

Thanks Fazer. I plan to take it apart again and probably replace the vacuum hose. The fuel hose is kind of short too and is hard to connect. I think it may have shrunk in length over time. I want to make sure there isn’t something else I have overlooked before I do because taking it out for a long ride to test it may leave me with a long walk back. The diaphragm was also hard to fit like maybe it had shrunk too. I wonder if there could be a leak there also.

If the fuel line isn't hard to connect, it's likely too long. I'm betting you kinked the vent hose on the reinstall. A new vacuum petcock line is a good idea also.

[ktoal54]

Does the vent go down thru the center toward the ground? I seem to remember it being hard to route back thru.

[Daniel Meyer]

Yep, likely the vent hose.

Also, did you *test* the petcock after putting it back together? (vacuum leak down/etc).

[longrider]

I like so many others have owned more than one valkyrie since 1998.    I have two more to work on as well as my own for a total of four. .  Each time I remove a tank for any reason I test out the operation of the petcock.  I keep a 3' length of fuel hose and push it on then lay the tank flat on the bench with the petcock hanging over and the hose pointing straight down in a gas catch can. .   The fuel selector is left in the off position.  I apply vacuum with a short length of vac hose.  A  brake bleeder with a gauge works well.  Fuel should not flow when vac is applied.  Open to  the run position to test and then to reserve.  Fuel should stop and start with the vac off and on in both run and reserve. .  I do change the vac hose to the petcock  every couple of years on these bikes.

[Valkorado]

If the fuel line isn't hard to connect, it's likely too long. I'm betting you kinked the vent hose on the reinstall.
[/quote]

I second.  That stubby fuel line has had me speaking French a few times.

[Factor]

Curved hemostats are your friend in such tight spaces.

[rug_burn]

    Another longshot thing it might be is the filter 'sleeve' inside the tank-  if you just replaced the diaphragm, at the sleeve or somewhere in the rest of the valve there might be varnish, rust or debris clogging things up. 
   This would especially apply if your gas went bad and gunked things up...
   
   

[ktoal54]

Sorry, I got sidetracked from the bike when I hit a waterline removing baseboard in my house. I was pounding the old nails (small brads) in instead of pulling them and one went right thru the metal protector and into the main water line. Must have gone 90% of the way thru when the shoot it the first time.


Back to the Valkyrie. The vent line isn’t kinked. I didn’t remove the petcock. I just took the flange off that holds in the diaphragm. I am back to leaning toward cracks in the vacuum line. I have lived in Arizona now 6 years and the bikes 21 years old.

[Jruby38]

crap can the OEM pos and install a  Pingle. I did at first leak 15 years and 100k miles ago.  You can WFO and not starve for fuel. The only thing worse than the oem petcock is the cheep wrinkle plastic chrome.

[ktoal54]

Sounds good to me. I questioned to new diaphragm Honda sold me. It didn’t seem to fit correctly, like it has shrunk. I am not leaking fuel but I suppose it could be leaking air in.

[gordonv]

The OEM bike doesn't have an external fuel filter. So is there any other mods to the bike's fuel system?

Open up your fuel tank cap, hold it open with something like a straw, and see if you keep getting the same problem. If not, then you have a venting issue.

[ktoal54]

 No other mods. It didn’t do it last time I rode.
 It’s hard to tell because it takes 10+ miles at highway speed before it does. I hate to go on too many rides that far away and have it quit all together. I just replaced the vacuum line and will test it again.

[Chrisj CMA]

I truly believe three things about the OEM petcock:

1.  When working perfectly, they flow very close to minimum requirements so any degradation in flow will be felt quickly

2.  It’s made out of what I call pot metal which I feel accounts for inconsistent quality. Some last a long time and some not so much

3.  Once they start to fail it’s not worth rebuilding. Replace with a quality valve is the more reasonable repair.

JMO