follow up to "Gasping for Fuel" answers

[Mike M in ohio]

     First, I appreciate all the suggestions for my fuel starvation at startup.
     I am ready to spring for the Pingel, but the last reply, about the fuel cap vent being clogged seemed to fit what I was experiencing. She was starved for fuel, until I opened the cap, allowing air in, and then she'd start and run fine. Today, I kept cap loose and got three proper fire ups.
     So, I'd like to check the simplest path first. I have an 03 with the large oval chromed cover, that has the cap which hinges up after the key is inserted and turned. Where is the vent on this cap? I looked all around, including under the rubber gasket. Is it there? Or, is it elsewhere? If the problem is a blockage, I'd attempt to clear it as best I can.
     Also, if the vent turns out NOT to be the problem, I would probably spring for  the vacuum Pingel. In that case, do I keep the vent line and attach it to the Pingel? As opposed to the manual Pingel, where you lose the line and cap the end.
     Thanks for all the previous leads on this and thanks for todays replies. The info here is invaluable, and the members are top notch.                             Mike in New York

[Gryphon Rider]

It's usually better to reply to your previous post than start a new thread, as it keeps all the information together.  You can even modify your original post if doing that makes sense.

The vent really has two parts to it.  One is a steel tube inside the tank that runs from near the filler neck (I haven't actually seen this, as I think it ends behind the filler neck) down to the bottom back end of the tank, where is sticks out as a nipple.  It is welded inside the tank.  The second part is the rubber hose that connects to that nipple, then runs down a few inches to a plastic tee, then from the bottom of the tee to the bottom of the bike.  The third leg of the tee has nothing attached to it.  The purpose of the tee is to be a vacuum break, preventing road water from being sucked up into the tank.

A vacuum line works the fuel valve, not a vent line.  If you get a vacuum Pingel, I assume you would use that same hose.

[MarkT]

If you are having a tank vent issue, it's nearly always because the rubber tube connected to the tank vent nipple at the back, has been pinched or folded over while handling / reinstalling the tank. A temporary soln is to put a coin under the cap to break the rubber seal there, until you unpinch the line.  I removed the line on Deerslayer as it serves no purpose other than safety - if you fill the tank to the brim then park in the sun before using some, the gas can expand out the vent and be a fire hazard when dripping on the bike at the back of the tank.  Don't fill the bike and park it.  Get your gas after lunch.  Or don't top it all the way up.

I was glad to be rid of the vacuum function of the OEM petcock.  In fact I removed that before I replaced it.  I would not buy a Pingel with that function.  If you can't remember to always shut off the fuel, install a Dan-Marc to do it for you.  More reliable than vacuum petcocks.  It's only about $30 and an afternoon in the garage. Considerably cheaper than the $230 price of the vacuum Pingels. And hydrolock is then prevented forever.

[Lyle Laun]

Mike:
As Mark T said, check the vent line off the back of your tank (behind the petcock about 4") for pinching or melting.
Your tank filler cap doesn't have a vent but if you want to change it out for a vented cap order a cap for a 1984 Honda VF700C  Honda part #17620-MB1-033
These are vented and will replace your non vented cap.

Lyle

[MarkT]

Mike:
As Mark T said, check the vent line off the back of your tank (behind the petcock about 4") for pinching or melting.
Your tank filler cap doesn't have a vent but if you want to change it out for a vented cap order a cap for a 1984 Honda VF700C  Honda part #17620-MB1-033
These are vented and will replace your non vented cap.

Lyle

Lyle, do you know if that vented cap has a check valve on the vent, so fuel can't leak out if the bike is dropped?  No description at Partzilla.

[Lyle Laun]

Mark
No idea on that, all I know is that I've been told that this is the one you would use if your vent line inside the tank has a hole in it and you can't fill your tank all the way up without it leaking out.

Lyle...

[MarkT]

I need a vented cap so I ordered one.  I'll look for a check valve & report on it.

[MarkT]

As I said above - checking the gas cap Honda part #17620-MB1-033 - yes it does have a check valve in the vent.  You can suck on the bottom of the cap but blowing is blocked.  Apparently it should impede gas running out if you drop the bike.  But might not stop it.  It does not stop the pressure of a fuel pump pushing against it. That's not a lot of pressure - around a couple pounds delivered by R&M's fuel pump IIRC. 

Twice on the Inzane ride I had a fuel overflow.  Once because some Harley smartass threw all the switches on my left handle bar including the fuel pump switch.  I switched them back (choke was full on, wouldn't start, and high beam) but missed the fuel pump - didn't suspect mischief sufficiently.  Could have bumped the high beam, but the choke?  Uh-uh.  I soon had an overflow running down the tank as the belly tank contents ran out the vent hole by the filler cap. Could have been a disaster but I got it wiped up and the rest evaporated.  Crotch was soaked.  I know it was no accident and am sure it was the HD driver who was alone with my bike while I took a leak.  The other time, I had to keep the tank fairly full due to starvation from fuel line issues I have since fixed - it takes 9 minutes to transfer all the fuel so you can figure how long to run the pump to bring up a gallon or so.  Forgot to shut it off in time.

I had planned to make shutoff automatic but the fuel pressure sensor I bought doesn't work with a diaphram type pump.  I figured, oh well, I don't need to make it "idiot proof".  I'm not an idiot.

Rethinking that now...