Fuel pump, help

[cheeseman1969]

I got a 4.5 gal tank on the back rack. I have a fuel pump under it with lines T'ing into the main line. When I have the tank fully fueled up, gravity takes care of just about anything to 70 mph. Once I start to get below ~2 gal left. Anything over 65 the bike start to slow and if going up a hill, slows down big time. So flip the fuel pump and off I go.
 I have noticed when I come to a stop or even just below 15 mph and park, the overflow tube from the main tank start to have gas coming out. A drip drip. So wondering if my regulator (silver circle ones at O'reilly's)  was letting to much gas through. i did a test of the different settings. I had it on 3. At full open on regulator, I got .5 gallons in 1 minute. It went down from there. So I tested my tank too. It had ~3 gal in it. It was also .5 gallons a min. Wondering what is going on now as I should not be seeing gas dripping out.

[cheeseman1969]

Oh to add. The bike was desmogged by previous owner. There is a tube from the main tank down to the center of the bike. that is where the gas is coming from.

[John Schmidt]

If that tube is coming from the back end of the tank and is about 5/32" in diameter(window washer line size), that's the breather tube. If the tank is overfilled on a hot day it will also drip there. As for the loss of fuel when the tank is getting low, that sounds like your main line isn't running downhill all the way from the petcock. Or possibly has a dip in it so that when the fuel level is low, there's less pressure from above to overcome it. I'd check the main line from the petcock, make sure it's flowing downhill, your symptoms are familiar and sounds like what others have experienced with that problem. All the fuel pump is doing is overcoming the loss of gravity pressure from a low fuel level in the bike's main tank and it sounds like it's causing it to be overfilled as well.

[gordonv]

You mentioned that you have the lines connected with a T.

Do you have any one-way valves to stop the flow of fuel back into either tank?

I was thinking after turning on the fuel pump, any fuel the carbs can't handle, is being forced back into the mc tank, causing it to over fill.

[cheeseman1969]

John - I will check that out. I have the tank off, just need to pull the air box to see. I did replace fuel lines about 2 years ago.

Gordan - I do not, but that is a great idea and never thought about that. I do have a shutoff value for the rear tank that I can reach while riding. I just use the rear tank first, then the main. When I switch, I hit that value.

[John Schmidt]

John - I will check that out. I have the tank off, just need to pull the air box to see. I did replace fuel lines about 2 years ago.

Gordan - I do not, but that is a great idea and never thought about that. I do have a shutoff value for the rear tank that I can reach while riding. I just use the rear tank first, then the main. When I switch, I hit that value.

You probably need to turn the petcock off when using the rear tank so it doesn't force back flow into the main tank. That's probably where the fuel(some of it at least) is going when you turn on the pump when the main tank gets low. I still think your biggest problem is either a low spot in the fuel line or something similar. As stated before, the clue you gave is the engine falters when the tank is well below half full. Get the lines running downhill all the way and I think you'll cure the problem. Then when using either tank, shut off the valves for the other tank to prevent backflow into it.

[WintrSol]

I got a 4.5 gal tank on the back rack. I have a fuel pump under it with lines T'ing into the main line. When I have the tank fully fueled up, gravity takes care of just about anything to 70 mph. Once I start to get below ~2 gal left. Anything over 65 the bike start to slow and if going up a hill, slows down big time. So flip the fuel pump and off I go.
 I have noticed when I come to a stop or even just below 15 mph and park, the overflow tube from the main tank start to have gas coming out. A drip drip. So wondering if my regulator (silver circle ones at O'reilly's)  was letting to much gas through. i did a test of the different settings. I had it on 3. At full open on regulator, I got .5 gallons in 1 minute. It went down from there. So I tested my tank too. It had ~3 gal in it. It was also .5 gallons a min. Wondering what is going on now as I should not be seeing gas dripping out.

How about some math? Say you get 35mpg at 70mph, that is 2 gallons per hour, or just over 0.03 gallons per minute. I'd say you can turn your regulator down a bit, but even at a lower rate, you will back-fill your main tank, unless you prevent it some how. I have a TourTank on the back of my Suzuki, and keep the main petcock off, until the fuel level in the aux tank is below the top of the main, but in my system, the fuel pump is after both tanks.

[MarkT]

Installed the belly tank, and set it up as a large reserve, which sends the fuel back to the main tank when it's needed.  Installed a 5/8" solenoid on the filler line (to the belly tank) and ran the fuel pump line to a T in the gravity fuel delivery line (OEM line).  At the gas station, I activate the solenoid and the fuel fills from the main to the belly while gassing up, ignition off.  It's powered by a latch relay that shuts off when ignition on.  (Has a red LED on the handlebar fuel panel indicating it's on) When I need the big reserve, I hit the fuel pump toggle sw (which activates a latch relay and lights up a green LED on the fuel panel) and it takes 9 minutes for all the fuel to transfer up to the main (and heads to the carbs at the same time) The fuel pump has a check valve.  So both tanks have positive flow control.  In addition, have the OEM petcock with it's original fuel reserve, and a Dan-Mark in the usual place (controlled by a latch relay, as documented before, for theft/hijack security) and an inline fuel filter.  Had to do some tweaks, to deal with fuel starvation - had a loop that flowed uphill, caused a problem.  And too much restriction on the flow from the first fuel filter I tried.  Works well now, except I still need to implement the auto-shutoff feature for the fuel pump.  The pressure sw was incompatible with the pulsing fuel pump.  Looking at oil level switches.  Also want to prevent overfill of the main if there isn't 3 gallons of space when the fuel pump is activated. So I need two fuel sensing shutoff switches.  It's not idiot proof yet.  However there's also the concern that more complexity = less reliability.  Something else to break.

[Punisher]

Make it so you don't have to flip the petcock and valve on aux tank.

Use a toggle switch and a couple of dan-marc fuel valves to open/close based on which source you want your fuel coming from.

I do that with my belly tank.   I use a three way switch, one side is gravity feed from the main tank, other side is the belly tank, in the middle, all dan-marc valves are closed and no fuel flow.    The toggle switch gets it power via a relay that is triggered by one of the wires on one coil (black-white I think?).   That way the bank angle sensor can kick in if needed and close whichever dan-marc is open at the time so fuel is stopped if the bike is down.

[MarkT]

Make it so you don't have to flip the petcock and valve on aux tank.

Use a toggle switch and a couple of dan-marc fuel valves to open/close based on which source you want your fuel coming from.

I do that with my belly tank.   I use a three way switch, one side is gravity feed from the main tank, other side is the belly tank, in the middle, all dan-marc valves are closed and no fuel flow.    The toggle switch gets it power via a relay that is triggered by one of the wires on one coil (black-white I think?).   That way the bank angle sensor can kick in if needed and close whichever dan-marc is open at the time so fuel is stopped if the bike is down.

Yep.  I do the same.  The bl/wh wire, accessible at the coils, at the ECM, and also at the kill sw and the loom that connects to it.  I used a latching relay, triggered by a hidden pushbutton, and powered by the bl/wh wire in the ignition circuit - kill sw, ignition sw, or tipover all shut off the fuel.  And it must be activated after turning on the ignition, or fuel will run out in about a mile.

[cheeseman1969]

Ok, I went up to Omaha NE and stopped in to the Nebraska Motorcycle parts store. Was asking about a shutoff value. When I showed him my fuel line, 3/8. the same as the val fuel lines, he looked at me and was wondering if I was riding a motorcycle. He says that fuel lines are ussually 5/16 or smaller. I guess the Val lady liken BIG!! LOL
 can some send me directions or point me in the right directions on doing the Dan-marc? I know that I can do it but like to have something in front of me so I can get it done in a day instead of 5 days. I forget to get things or don't think about it till I need it. Also do I put my in-line fuel filter after my main tank too? Right now it is just filtering the secondary tank. I was depending on the petcock to do that but I guess not. Some of you have me afraid now. LOL

[MarkT]

http://www.horseapple.com/Valkyrie/Tech_Tips/Fuel_Shutoff/fuel_shutoff.html

I put a fuel filter just before the Dan-Marc on Jade.  Took some effort to fit it in there, with a T-fitting from the belly tank fuel pump and still have enough flex in the line to be able to move it onto the petcock.  And with no kinking or fuel flow restrictions for gravity feed.