Won't stay running then wont start. HELP !!

[Roidfingers]

  I installed a quick disconnect kit for the fuel line today. Also purchased and installed a longer vacuum line to the petcock. To make it easier to hook it up. The fuel control valve is on correct ( I think ) in the on position it will no longer turn counterclockwise. Engine started right up but then seemed as if it was starving for fuel. Thought maybe vacuum issue so opened fill cover and still stalling. HElp please>

[Chrisj CMA]

I installed a quick disconnect kit for the fuel line today. Also purchased and installed a longer vacuum line to the petcock. To make it easier to hook it up. The fuel control valve is on correct ( I think ) in the on position it will no longer turn counterclockwise. Engine started right up but then seemed as if it was starving for fuel. Thought maybe vacuum issue so opened fill cover and still stalling. HElp please>

probably the disconnect thing

[Hook#3287]

Check for a kink in your new petcock vacuum line.

[Roidfingers]

Got frustrated after putting all back together. Gonna dismantle and retry again tom.

[sandy]

The petcock selector is in the wrong position. Remove it and figure the position you're in and then put the selector on in the right position.

[Roidfingers]

Well and how do I do that? what the steps?

[John Schmidt]

Remove the control knob and manually turn the control on the petcock all the way in either direction, then attach the outer control knob with the pointer aimed in the same direction....all the way in either direction, depending on which way you manually turned the petcock.

As for the quick disconnect, those have proven to be a problem for most. Keep in mind with this gravity feed system, everything has to always be running downhill from the petcock. Many have also extended the length of the fuel line, only find it creates a low spot in the line and when the tank gets well below half full, the engine will begin to starve.

[Roidfingers]

Thanks all. I'm gonna pull the tank again and remove that quick disconnect. Wasn't any easiers to hook up because now you have two moving ends to try to push together. Original way at least the petcock didn't move. I'll let you know.

[Paladin528]

You cannot put it together wrong.  the knob only goes on one way.  If you can get it wrong then the knob is broken.
I would more suspect the quick disconnect is not letting enough fuel through for her to drink.  The flow from the tank is very finicky when it comes to change.  Even making the fuel line longer will cause her to starve.

[indybobm]

I agree, you cannot put the knob on 'wrong'. Actually you can but it would be very noticeable.
The knob should be installed so that the pointy part can be in the 12:00, 9:00, and 6:00 position. If it is in the 9:00, 12:00, and 3:00 position (for example), it is 90 degrees off.

[Roidfingers]

Yea I was pretty sure of the knob being correct. the stem on the petcock is flat on one side. I think its the quick disconnect. Will let you know as soon as I can get to it and throw that dam thing in the trash.

[indybobm]

This brings up a good point. Not all Valkyrie petcocks have a flat on just one side. There are Honda OEM Petcocks that have four flats and it is possible to install the knob incorrectly.

[MarkT]

Keep in mind with this gravity feed system, everything has to always be running downhill from the petcock. Many have also extended the length of the fuel line, only find it creates a low spot in the line and when the tank gets well below half full, the engine will begin to starve.

John, I've heard this before but it didn't make sense to me since there is a head of pressure above it, flowing uphill should make no difference at all.  So when installing my belly tank and replumbing it as a large reserve, I had to increase the overall length of the fuel line to install stuff.  What I installed was a T-fitting from the belly tank fuel pump, a Dan-Marc, and a fuel filter.  To get that in the line and still connect to the OEM petcock (modified so not vacuum) I had to put a vertical loop in the line.  And got starvation.  I blamed the fuel filter and replaced it with a free-er flowing one.  Still starving.  Redid the fuel line in larger diameter ( had a restriction due to compression fitting hardware ). Still starving.  Got rid of the large loop and the compression stuff and redid it with 3/8" soft copper tube carefully bent with a tube bending spring to minimize flattening (but it still flattened a little). Still have a small vertical loop in the line that goes uphill.  I couldn't test it due to snow and that's where it is right now.  And I still can't test it yet.

But the problem with uphill flow makes no sense to me, with a head of even just gravity pressure above it.  Like, it doesn't matter if there's only a little pressure, as long as the level of the gas is above where you want it to go.  That's how a siphon works.  Can you explain it so that downhill-only thing makes sense to me?  If it's a bubble of air - how would that stop the fuel, and why would it work with a full tank? Couldn't the gas just push past it?  Are we seeing an air bubble is sufficient backpressure that may impede the head of pressure above it, once the latter is reduced? Not sure I get that it could stop the fuel from leaking past it anyway. BTW I have not yet tried turning on the fuel pump to see if that overcomes the issue.  That is next if it happens again.

Here's a shot of what that part of the plumbing looks like right now.  The flow goes from bottom up to the marked filter in the copper loop.

[indybobm]

MarkT, maybe a good test would be to try to siphon gas from a container with a loop in the siphon hose. Would it be like a 'J' trap in a sink drain?

By the way, I notice your petcock has four flats on the shaft.

[MarkT]

It has a rounded corner.  I'm careful to install it correctly.

[Fazer]

John and Mark have a good discussion going about the gravity feed system. I am interested to hear how Mark's fuel connection works out.  When I desmogged and added the Dan Mark I replaced the fuel lines going to the carb banks and to the petcocks, but was careful to make the lines the same length, after reading on the forum that others have had fuel delivery issues if extending the length of the lines--mostly resulting in kinks, as I recall.  So far mine has been working as it should.

We would often times make a loop in our fuel lines for our model plane engines when mounting an inverted engine to prevent fuel from flowing into the carb when the engine wasn't running.  The two stroke gas engines we use mostley have Walbro carbs that pull fuel and the glow engines often use a pressure line from the muffler to the fuel tank for a little assist in fuel flow.  FWIW.

65F predicted for Sat.  Can't wait!

Greg

[indybobm]

We would often times make a loop in our fuel lines for our model plane engines when mounting an inverted engine to prevent fuel from flowing into the carb when the engine wasn't running.  The two stroke gas engines we use mostley have Walbro carbs that pull fuel and the glow engines often use a pressure line from the muffler to the fuel tank for a little assist in fuel flow.  FWIW.

65F predicted for Sat.  Can't wait!

Greg

I was in RC planes a number of years back. From what you are saying about the loop keeping gas from flowing to the walbro carb sounds like the loop might add a restriction to flow.

Going to be 65 here in Indiana too Saturday but rain is predicted.

[John Schmidt]

Mark, I agree....I don't think it should make any difference. Yet, how else does one explain the results when removing the sag in a line with extra length or getting rid of an uphill run cures a starvation problem. I often wondered if that issue possibly made the bike more prone to intermittent vapor lock in the low area. I do know from experience as a kid with siphoning gas from my dad's car, if the tank was really low(most of the time on a teacher's salary) it was more difficult. Took at least three mouthsfull to get it started.  

[Fazer]

You are correct Indybohm.  The loops were used with the glow engines.  Always tried to keep the the carb level with the top of the fuel tank, but when mounting the engine inverted, had to deal with fuel flowing into the carbs and flooding the engine.

[Roidfingers]

  Ok. Well got the fat girl back and running strong. It was all about that dam quick disconnect. Actually when I pulled of the male end from the original fuel line, I popped a hole in the end. Cut it out then I got a 2 1/2 inch piece of fuel line and put a barb in It and attached to original after cutting off about a half inch where hole was. So now I have a longer vacuum line and a longer fuel line so I can rest the tank on the frame , connect everything then lower in place. So easy. And running strong. If someone wants this quick disconnect you can have it free or its going in the trash.

[MarkT]

Mark, I agree....I don't think it should make any difference. Yet, how else does one explain the results when removing the sag in a line with extra length or getting rid of an uphill run cures a starvation problem. I often wondered if that issue possibly made the bike more prone to intermittent vapor lock in the low area. I do know from experience as a kid with siphoning gas from my dad's car, if the tank was really low(most of the time on a teacher's salary) it was more difficult. Took at least three mouthsfull to get it started.  

John, if after I can test it again ( the snow is still here from a month ago and the temps have been bumping 60; while there's snow coming again - I HATE DECEMBER ) and it still has the problem - I will pull the tank and completely rebuild the fuel path from tank to carb rails with my needed mods, with a focus on consistent downhill, with most of it 3/8 soft copper tube with swage or sweated solder fittings.  For minimal restriction at junctions.

[John Schmidt]

Mark, take pictures, I might be interested in copying it if it works good. 

[Firefighter]

My experience is with an extra fuel filter that I added under the tank. Ran fine with a full tank but below half tank the engine would run out of fuel. I think there was not enough head pressure to push the fuel through the filter. I know the fuel was going down hill but not enough fuel would get through the paper filter to supply six carburetors.

[Valkpilot]

Ok. Well got the fat girl back and running strong. It was all about that dam quick disconnect. Actually when I pulled of the male end from the original fuel line, I popped a hole in the end. Cut it out then I got a 2 1/2 inch piece of fuel line and put a barb in It and attached to original after cutting off about a half inch where hole was. So now I have a longer vacuum line and a longer fuel line so I can rest the tank on the frame , connect everything then lower in place. So easy. And running strong. If someone wants this quick disconnect you can have it free or its going in the trash.

Beware the longer fuel line.  If it droops at all you may have fuel starvation (effectively vapor lock) in hot weather.

[MarkT]

Mark, take pictures, I might be interested in copying it if it works good.  

I went ahead and ordered the parts for the shifter pivot mod from Mcmaster - and while there looked around.  DAMN I wish I knew about them before.  It's like a SUPER HARDWARE store. I will be a regular customer, that's for sure.  Anywho I looked around in the tubing fittings section and found some great parts I was trying to make.  They will be called on to do my fuel mods if I still have trouble and I suspect I will. Wish I had time to work on it now but Xmas and family obligations and an upcoming trip and a trip I just took to help a disabled friend hunt out of state, and customer orders are chewing up my time. Also will be making up a bunch of jack adapters pretty soon as I mentioned in a previous thread. Not to mention the driveway is snow/iced in and it's snowing again now.

BTW, firefighter, I found the fuel filter provided by the belly tank people has much better flow-thru than another one I got from NAPA which is the same one I used on my Honda garden tractor.  I couldn't find any pics of the filter, I didn't shoot it; mine is installed where you can't see it w/o pulling the tank.  Their install doc says it is a Wix 33027.  Their website is http://www.rmworksinc.com/Information.html