Fuel filters not filling... - Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums
Carbs and Fuel System
From the gas tank to the carbs
All fuel system discussion

LinkBack Thread Tools Display Modes
post #1 of 15 (permalink) Old 08-16-2007, 02:38 PM Thread Starter
Junior Member
Join Date: Jul 2007
Location: Kissimmee, FL
Posts: 20
iTrader: (0)
Angry Fuel filters not filling...

This might be related to my previous post below about the leaking petcock but I think it might be a totally different problem. Basically, I've removed the petcock diaphram so that fuel flows freely down the lines. No more vacuum hose. I sealed it with a makeshift gasket so NO MORE LEAK either. I installed a clear plastic filter on each line right out of the petcock. Here's the problem... the rear-most fuel filter fills up nicely while the front-most stays almost empty. Now, if I tip the tank forward then the front filter fills up all the way but the rear one empty's out. When I take her for a ride she'll last the 3 minutes perfectly and then starve. I'm assuming she's living off the float bowls but not replenishing. When I watch the filters closely, you can clearly see the fuel easily flowing into the full filter but not the empty one. When I tip the tank it's vice versa. My question is, by installing the filters does this mean that the suction from the carbs that was once enough to draw gas is now too small? Do I need to somehow increase the 'pull' power from the carbs? And why aren't the lines drawing fuel equally from both sides of the petcock... only from the side which is tipped? I'm pretty sure there's no blockage in the petcock since I can easily blow air through one and out the other and, like I said, when I disconnect both lines fuel flows quickly from both. BTW, here's a quick little test I did. I waited for the bike to start starving and watched as the one filter emptied. I shut her off and waited to see if any fuel flowed into the empty filter. Nothing. But as soon as I disconnected the filter from the petcock a gush of fuel came out. Any ideas would be most helpful!
jaytango is offline  
Sponsored Links
post #2 of 15 (permalink) Old 08-16-2007, 03:49 PM
Calif Rider
weh44att's Avatar
Join Date: Jan 2006
Location: Petaluma Calif
Posts: 725
iTrader: (0)
Have you tried to swap the filter to see if there is a problem with the rear filter. You may have done this already.

2004 25,500 miles
Led tail light enhancement
Homemade floor boards
Headlight modulator
Extra heat sink on R+R
R+R relocation
Homemade driver's backrest
Fused Stator
Mcct conversion-cost 4.50
Ride-on in tires
crash bar with home made hyway pegs
iridium plugs
home made fork wind deflectors
coil pickups adjusted.
Kenda kruz tires 110/90 170/80
weh44att is offline  
post #3 of 15 (permalink) Old 08-16-2007, 04:09 PM Thread Starter
Junior Member
Join Date: Jul 2007
Location: Kissimmee, FL
Posts: 20
iTrader: (0)
Yes I did. As soon as I swap them and start the bike, the one that was full starts emptying and the empty one starts to fill. With about 30 seconds they look exactly like before the swap.
jaytango is offline  
post #4 of 15 (permalink) Old 08-16-2007, 06:33 PM
Join Date: Mar 2007
Posts: 203
iTrader: (4)
Is one filter higher then the other?
piromedicx is offline  
post #5 of 15 (permalink) Old 08-16-2007, 08:42 PM
Members who have donated towards server costs
Crobins365's Avatar
Join Date: Jul 2006
Location: Kennett Square, PA
Posts: 3,505
iTrader: (48)

Curious, although the only thing I can think of that can affect carb pull is that they might be out of sync. However, the tipping of the tank makes me lean in Piro's direction. Were the carbs sync'd before you put the filters on?

Crobins365 is offline  
post #6 of 15 (permalink) Old 08-16-2007, 09:11 PM
Old Truck Junkie
niterider's Avatar
Join Date: Jul 2007
Location: Roby Texas
Posts: 4,130
iTrader: (15)
Try opening the fuel cap while bike engine is running. Also tap the carb with a wrench and see if the fuel flows better.

02 honda sabre 1100
niterider is offline  
post #7 of 15 (permalink) Old 08-16-2007, 11:29 PM Thread Starter
Junior Member
Join Date: Jul 2007
Location: Kissimmee, FL
Posts: 20
iTrader: (0)
The filters look the same height although the petcock tilts slightly downwards towards the back of the bike because of how these gas tanks are. The bike ran PERFECTLY up until I decided to pull the tank to clean it. It was all rusted (REALLY BAD... I'm talkin thick rust all over, no clean metal). I ride 20 miles to work and back and never had a problem. I just figured it was only a matter of time before the rusty tank caused trouble. I tried to clean it but still looks like crap inside. Because of this I installed the filters. I also took apart the petcock and cleaned it (that's probably when I damaged the diaphram and had to toss it). I didn't even touch the carbs though, so I don't think they could have gotten out of sync. I tried the fuel cap but no go. The only way to get even flow is to lift the tank about 4 inches in the back so the petcock is parallel to the ground. But obviously I can't ride like that. I'll try the tappin'.
jaytango is offline  
post #8 of 15 (permalink) Old 08-16-2007, 11:51 PM Thread Starter
Junior Member
Join Date: Jul 2007
Location: Kissimmee, FL
Posts: 20
iTrader: (0)
A pic of the filters

Here's a pic...
Attached Thumbnails
Click image for larger version

Name:	filters.jpg
Views:	37
Size:	36.0 KB
ID:	584  
jaytango is offline  
post #9 of 15 (permalink) Old 08-17-2007, 04:57 AM
and the Adventure Cycle
hyperbuzzin's Avatar
Join Date: Jun 2004
Location: Western PA
Posts: 6,138
iTrader: (1)
There was mention of being sure to use hi-flow filters when adding them to a normally functioning fuel system, not sure if that'd be an issue with a modded petcock like yours though?
Have ya tried switching the line itself (after the filters) from the front to the rear, and rear to front? Don't know what that'd prove, but couldn't hurt to try.

AKA: Tim & 'The Adventure Cycle' VROC #24567, NEVROC, SteelCity VROC

"When life throws you curves,
Aim for the apex."

Author Unknown
hyperbuzzin is offline  
post #10 of 15 (permalink) Old 08-17-2007, 10:50 AM Thread Starter
Junior Member
Join Date: Jul 2007
Location: Kissimmee, FL
Posts: 20
iTrader: (0)
Hmmm... That's a good point. I didn't think about high flow. That could be an issue. I'm almost tempted to remove the filters for just a quick test but I'm too afraid with the condition of that tank. I did notice last night that she performed a lot better, didn't completely starve when i took her out. Just a little more rough than normal. I'm wondering if the system just needs a good run just pumping gas through to get some gunk moving out. I'm definitely gonna try the seafoam and see what that does. Another thing I'm wondering is if the added length of the new hoses and filter has affected the carb sync. I'll check into that too. Just wanna say thanks for all the help I've been getting. First bike and all, it's good to know we have such a great community!!!
jaytango is offline  
Sponsored Links


Quick Reply

Register Now

In order to be able to post messages on the Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

Once registered, your User Name"cannot be changed". We can make exceptions within 7 days, but after that, it is set in stone.

User Name:
Please enter a password for your user account. Note that passwords are case-sensitive.


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:


Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode

Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

For the best viewing experience please update your browser to Google Chrome