Front cylinder loosing fuel at +75 mph - Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums
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post #1 of 9 (permalink) Old 07-21-2012, 03:41 PM Thread Starter
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Front cylinder loosing fuel at +75 mph

Riding down the road she'll lose fuel to the front cylinder, evident by loss of fuel in seen through clear filters, and sputter a bit, sounds like its bogging out and becomes unresponsive to twists of that ol right hand. Now see here, my bike is a POS that was abandon for 10 years in a basement, its frustrating. I've done the ear shave and removed the CA crap so far

Could it be a ****ty vacuum hose or plug? Is it my leaking fuel shutoff valve(yea, it drips a little)? Perhaps carbs out of sync? Crap gas cap(which it is)? And I have one other Q; should I have the lines at the base of the fuel tank(CA) plugged?

Thanks so much
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post #2 of 9 (permalink) Old 07-21-2012, 04:17 PM
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restricted fuel flow.....which is what you are describing as seen through clear fuel filter.

This could be a blocked screen in the tank, a bad or restricted petcock, or a leaky gas line...maybe it's losing it's prime??

:Q; should I have the lines at the base of the fuel tank(CA) plugged:

As far as the lines at the base of the tank (near nose of the seat), in a non CA bike it is vented with a hose to the bottom of the bike. In a CA model the second hose goes to a canister for emissions....I think it is OK to leave open as well.

The tank may not be venting properly through the cap...and definitely can't vent if the vent line is capped off.
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post #3 of 9 (permalink) Old 07-21-2012, 04:55 PM Thread Starter
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Hey, thanks for tips.

I plan on tearing apart the petcock and checking out the gas cap here in a couple hours, once it cools off outside. Hopefully it'll be a easy fix.
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post #4 of 9 (permalink) Old 07-21-2012, 08:58 PM Thread Starter
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So, tore apart the petcock, tore apart the cap. Still sputters.
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post #5 of 9 (permalink) Old 07-22-2012, 08:40 AM
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The cap vents the tank through a hole at the base of the cap...near the hinge. You will see a hole that the cap mates up with. That hole leads to the tube at the bottom of the tank near the seat (on the inside of the tank).

If that tube at the bottom of the tank is capped off, then the tank will not vent. run a rubber hose from that tube down to the bottom of the bike so it can vent.

It is also possible that you have a carb issue if one fuel lines is flowing and the other one is not.
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post #6 of 9 (permalink) Old 07-25-2012, 03:07 PM
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Sticking fuel petcock vacum valve is the problem. Had same problem few times. Suck and blow petcock trough vacum hose when engine died and it runs again. This problem appeared my bike sometimes in spring after long winter pause. Problem is the fuel, clogging petcock. Have repaired petcock with new inside parts and it solwed this problem mostly, sometimes it still appears after longer driving pause.
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post #7 of 9 (permalink) Old 08-01-2012, 10:09 AM Thread Starter
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Just ordered a new vacuum-less petcock stock in the Yamaha TW200, I've decided not to fiddle with the stock vn750 petcock any more, I don't like the vacuum set-up anyways. Hopefully I can figure out my electrical problem so I can continue to figure out this problem.
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post #8 of 9 (permalink) Old 08-01-2012, 11:11 AM
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Quote:
Originally Posted by Ticked View Post
Just ordered a new vacuum-less petcock stock in the Yamaha TW200, I've decided not to fiddle with the stock vn750 petcock any more, I don't like the vacuum set-up anyways. Hopefully I can figure out my electrical problem so I can continue to figure out this problem.
I don't know why people continue to order those, but they don't put out enough fuel for our bikes.

1986 Kawasaki Vulcan 750
NGK Iridium Plugs #7803/DPR7EIX-9
Duralast Gold ETX15 AGM Battery
Coastered & Shaved
TOC MCCTs
Metzeler ME880 [110/90-19, 170/80-15]
Balance Dampers Replaced
Tuxedo Mod
Rebuilt Forks w/ Progressive Springs
V&H Cruzers
VN750.com Grill Cover
Meanstreak Seat
Emgo 23-92411 Handlebars
MOSFET FH012AA R/R


1990 Kawasaki Vulcan 750

1998 Honda VFR800 FI

2014 Honda VFR800F

1989 Pontiac Firebird Formula 350
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post #9 of 9 (permalink) Old 08-01-2012, 11:20 AM Thread Starter
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Yeah, I'm a little unsure how the petcock will work out, I saw a post from RxRC implying he has installed it and it works. I figure for 15 bucks its worth a try at least.
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