Kawasaki VN750 Forum banner

1 - 20 of 81 Posts

·
Registered
Joined
·
738 Posts
Discussion Starter #1 (Edited)
Fergy PM'ed me to suggest making the instructions to correct and prevent POOGS a 'sticky' (Admin function). I think that it is a great idea. Thanks Fergy! So, here are the instructions to correct and prevent POOGS on '85-'06, non-CA models only. If someone has the instructions for CA models, please add them or PM me and I will add them to this post.

Subject: Phantom Out Of Gas Syndrome (POOGS)

Symptoms: Motorcycle stalls repeatedly as the fuel level in the gas tank falls below 1/2 full. Symptoms similar to running out of gas. Switching to Reserve has no effect.

Root Cause: Failed gas tank venting system; clogged gas cap vent and/or gas tank vent tube or a failed check valves within the gas cap vent assembly. This prevents air from entering the gas tank to displace fuel being used by the carburetors, resulting in negative gas tank pressure (or vacuum). Negative gas tank pressure prevents fuel from reaching the carburetors causing the motorcycle to stall.

Verification Steps:
  1. Fuel level at 1/2 tank of gas or less.
  2. Ride for a few miles.
  3. Motorcycle stalls as if out of gas.
  4. Pull over in a safe location.
  5. Open gas cap for 3-5 minutes. This relieves the negative gas tank pressure momentarily.
  6. Close gas cap
  7. With a few extra cranks the motorcycle starts like there is no problem
  8. Go to step #2 and symptoms repeat

Solution: Clean gas cap venting system and verify that the gas cap vent assembly check valves are functioning properly. Optional: The gas tank vent tube (’88 – ’06, non-CA models only) exits in front of the rear tire and may be rubbing against the spinning rear tire, resulting in a clog that resembles black carbon. Relocate the gas vent tube exit, if this is determined to be the debris source.

Gas Tank Venting System Cleaning Instructions: The process looks complicated, but it only takes about 15 minutes. NOTE: Instructions below are for ’85 – ’06, non-CA models only. Adjust accordingly for CA (vapor recovery system) models.

Step I: Clean the gas tank vent tube/exit.
For '85-'87 Models with no gas tank vent tube (click on View attachment 3602 for more information):​
  1. These models vent through a small port in the base of the gas cap. The port exit is located in the rear of the gas cap (see attachment above for details.)
  2. Open the gas cap.
  3. Locate the gas tank vent port entrance; a small hole located on the gas tank directly in front of the opened gas cap hinge.
  4. Spray carburetor cleaner or non-chlorinated brake cleaner, using the straw attachment, directly into the gas tank port entrance. The cleaner should exit the rear of the gas cap freely. Have a rag handy to prevent cleaner from running down the sides of the gas tank.
  5. Use a pipe cleaner or small plastic zip tie to unblock a clogged port, if necessary.
For '88-'06 Models with gas tank vent tube:​
  1. Place a piece of paper in front of the gas tank vent tube exit. The default (OEM) location is directly in front of the rear tire.
  2. Open the gas cap.
  3. Locate the gas tank vent tube entrance; a small hole located on the gas tank directly in front of the opened gas cap hinge.
  4. Spray carburetor cleaner or non-chlorinated brake cleaner, using the straw attachment, directly into the gas tank vent tube entrance until drips are observed on the piece of paper placed at the gas tank vent tube exit.
  5. Continue spraying until the drips run clear.

Step II: Clean the gas cap vent assembly.
  1. Open the gas cap and remove the key.
  2. Cover the tank inlet tube to prevent dropping parts in the tank. A large rag or towel is best as it will also help catch small parts and prevent them from falling on the floor (where they can be lost).
  3. Remove the two brass screws located on the bottom of the gas cap that hold the latch mechanism in place.
  4. Remove the latch mechanism. Note: there are loose components in the base that covers the latch spring.
  5. Inspect the latch, clean as necessary and then set aside.
  6. There are five small loosely mounted springs on the underside of the gas cap. They can be left in place for this operation or removed and set aside for safe keeping.
  7. Remove the small metal collar located on the end of the key cylinder’s male connector. The collar acts like a bearing between the key cylinder and previously removed latch assembly. It is loose and easily lost. Slip it off and put it aside for safe keeping.
  8. Hold the gas cap vent assembly in place while removing the two short screws located on the base of the gas cap vent.
  9. Wiggle the gas cap vent assembly back and forth to loosen it from and prevent damage to the gasket which is glued to the gas cap cover.
  10. Inspect the gas vent gasket for tears or bulges. The outline of the venting path depressed into the gasket should be visible (this is normal). Gently wipe with a clean cloth. Inspect the cloth used for signs of debris.
  11. Remove the small round plastic check valve/liquid separator located on the underside of the gas cap vent assembly (a pair of small needle nose pliers works well). Be careful not to damage the silicone valve covering the base of the check valve. This is the valve that allows air to enter the gas tank to relieve negative pressure. Remove the check valve gasket as well and place it aside.
  12. Inspect and clean the check valve. Pay close attention to cleaning the tiny 90 degree elbow which leads to the vent hole.
  13. Inspect the silicone valve located on the underside of the valve. It should be soft, pliable and moving freely.
  14. Inspect the small holes behind the silicone valve. Clean as necessary.
  15. Inspect the silicone check valve mounted in the gas cap vent assembly. This valve helps relieve positive gas tank pressure. It should be soft, pliable and moving freely.
  16. Inspect and clean the gas cap vent assembly air channels and vent hole. Pay special attention to the very small vent hole leading to the 90 degree elbow in the small round plastic check valve/liquid separator removed previously. This tiny hole is easily blocked by debris.
  17. Reassemble in reverse order.

Step II: Preventative maintenance.
  1. Repeat Step I frequently (at least once a year) to keep the gas tank vent line free of debris. Keeping the gas tank vent line clean will help prevent debris from reaching the gas cap vent assembly where it can easily block the air channels or small vent hole.
 

·
Registered
Joined
·
2,687 Posts
great post!
 

·
Patriot Guard Rider
Joined
·
825 Posts
Nice write up but I need the CA Version.
 

·
Premium Member
Joined
·
29 Posts
us from ca

how can you tell a us from ca bike

1985 vulcan 700
ngk dp6ea-9
backrest
Custom radiator cover
Custom Mirrors
Fork Bag...
Custom tank trim
 

·
Registered
Joined
·
57 Posts
After shutting off the motorcycle I hear a very loud venting noise from the gas tank and have figured I might as well clean both as said above. Question, you say to use carb cleaner on the vent hose, won't that eat the rubber alive? Also once I take off the tank cover/latch to clean in the 2nd part do I clean that with carb cleaner as well???

Also I couldn't seem to locate the end of that vent hose you say it comes out by the rear tire, where exactly if you don't mind me asking?

I also just bought a sack of marbles and am going to marble her tonight or tomorrow and play around with the air/fuel screws starting off at 2 turns :)
 

·
Registered
Joined
·
738 Posts
Discussion Starter #8 (Edited)
how can you tell a us from ca bike

1985 vulcan 700
ngk dp6ea-9
backrest
Custom radiator cover
Custom Mirrors
Fork Bag...
Custom tank trim
Sorry for the confusion on the reference to CA. CA refers to CAlifornia emissions. The California (CA) models have a gas vapor recovery system. Basically a charcoal canister and set of purge valves designed to capture gasoline vapor and recycle them back into the system (now standard on cars). You have a CA emissions model if there are two vent tubes at the base of the gas tank (visible when the seat is removed). The non-CA models have a single gas tank vent tube.
 

·
Registered
Joined
·
738 Posts
Discussion Starter #9
After shutting off the motorcycle I hear a very loud venting noise from the gas tank and have figured I might as well clean both as said above. Question,

1) you say to use carb cleaner on the vent hose, won't that eat the rubber alive?

2) Also once I take off the tank cover/latch to clean in the 2nd part do I clean that with carb cleaner as well???

3) Also I couldn't seem to locate the end of that vent hose you say it comes out by the rear tire, where exactly if you don't mind me asking?

4) I also just bought a sack of marbles and am going to marble her tonight or tomorrow and play around with the air/fuel screws starting off at 2 turns :)
The loud venting noise is a GOOD thing! It means that the venting system is functioning properly (i.e., air is enter the tank and making that noise). However, a 15 minute cleaning will not hurt and will provide peace of mind that the system is indeed free of debris.

1) To clean, just use a rubber safe cleaner that will not leave a sticky residue to clean the rubber vent line, like non-chlorinated brake cleaner or a carb cleaner that is easy on rubber parts. I like non-chlorinated brake cleaner because I can use it in other applications, like cleaning the mass-flow air sensors in my car. You decide what works best for you (everyone has their favorites).

2) You can use the cleaner selected above to clean all parts of the gas tank venting system. Again, whatever works best for you or is your favorite.

3) The default OEM exit for the gas tank vent tube snakes through the frame to exist directly in front of the rear tire, about mid point. However, the prior owner (if applicable) may have move the it. Trace/follow the gas tank vent tube through the frame or spray your cleaner of choice and look for the drips to locate the actual exit point.

4) Marbling - Search the existing threads or start a new one. This STICKY thread is devoted to POOGS
 

·
Big Dumb Viking
Joined
·
597 Posts
Just had POOGS happen to me on my way home from work a few minutes ago. Luckily...it happened as I was pulling into my neighborhood...and I'm just the 3rd house... Coasted to my driveway.

Looks like I have something to do later today after I wake up.

Thanks for this write-up! :smiley_th
 

·
Registered
Joined
·
77 Posts
Another cause of POOGS?

After seafoaming my fuel tank, had the POOGS at half a tank of gas the day after adding seafoam to the tank. Switched to reserve on petcock, nothing. Opened the gas gap, nothing. Wouldn't start after 1-2 dozen attempts to start over about a two hour timeframe until nothing was left in the battery. Got towed home. Trouble-shooting revealed excellent spark and determined it was a fuel problem (and the fuel system was the last thing I worked on).

There are three lines coming from the petcock. One supplying fuel to right carb, one supplying fuel to the left carb, and one that is a vacuum line. I filled the tank with gas and couldn't get any fuel to come out of the petcock at any setting. I then connected my hand vacuum pump to the vaccum line. Gave it a couple of pumps and heard a little "pop" and fuel began to freely flow from both fuel lines. I removed the petcock and dissembled it and cleaned the gunk out of the assembly and rubber gasket. I think seafoaming the tank loosened up stuff in the tank and was deposited in the petcock valve causing it to stick. The petcock consists of two valves, the one you turn to on, off, and reserve position, and the other internal valve, a rubber flap that blocks the flow of gas until a vacuum acts on it to allow gas to flow out of the petcock. That's where the gunk deposited making the flap stick. Put everything back together and it immediately fired up. I haven't had a problem since.

Now I need to perform the gas cap cleaning and vent hose cleaning to cover all my bases. If I'm all wet on this please correct me. I have no owners manual, just the Haynes and Clymers which doesn't go into how the petcock works. This is just what me and my neighbor (an ol' timey mechanic) kinda figured out with a lot of head-scratching. Hope this helps someone and contributes to the POOGS discussion.
 

·
Registered
Joined
·
77 Posts
POOGS again X 2

Since my last POOGS incident (I've had 3 total, the first one in above post happened in July) I've had 2 more. All three times it has happened after the bike sat in the hot sun. It's summer in Texas, so it's always been in extreme HEAT; but the three POOGS incidents have happened only after sitting in GLARING SUN.

The first time, while sitting waiting for a tow for 2 hours, I had the gas cap open but still over tank hole. Over the first hour I tried starting the bike several times with a 5-10 minute wait between attempts with no result. In fact, almost completely discharged the battery I tried so many times.

The second time, after pushing the bike a mile I got to a hill (of course after pushing it up the hill!). I coasted down, popped the clutch, and it started right up. Stopped on the way home and filled the tank (all three times it happened at half a tank or little over).

The third time (today) I had just over half a tank. Started fine, got on the highway, drove about 1.5-2 miles and it started POOGSing. Had to pull over on the shoulder. Waited 5 mins with cap off and tried to start it. Nothing. Waited another 5 min with cap off and tried again. Nothing. Fortunately I was 1/2 block from a gas station. Pushed bike to it, filled it up and bike started right up. Drove it home another 9 miles with no problem.

cglennon I have not done your POOGS remedy procedure but I"m going to now. I really think my problem is the rubber vacuum valve inside the petcock (referenced above). If I have POOGS again after that then I will be certain that is the problem, so I'm going to eliminate the vent tube, vent holes and gas cap assembly first. Summer is ending here so that may do it, too. It's strange because I never had any problems with POOGS until I seafoamed the gas tank and my problem started the next day. Do you think it affected the rubber diaphram in the petcock to make it sticky? I know a lot of folks here swear by seafoam, that's why I did it. Kinda wished I hadn't.

In the meantime I will carry a 60cc catheter tip syringe to apply a vacuum to the petcock if it happens again. I'm convinced if I had one today I could have fired it up. My brake bleeder vacuum pump is what fixed it the first time. Don't know really though, not a mechanic, just trying to learn here like many others...:blah:

-jim
 

·
Old Truck Junkie
Joined
·
4,133 Posts
I may have missed it in your posts, but have you replaced the vaccuum hose to the petcock. If not I would try that too.
 

·
Registered
Joined
·
738 Posts
Discussion Starter #14
Since my last POOGS incident (I've had 3 total, the first one in above post happened in July) I've had 2 more. All three times it has happened after the bike sat in the hot sun. It's summer in Texas, so it's always been in extreme HEAT; but the three POOGS incidents have happened only after sitting in GLARING SUN.

The first time, while sitting waiting for a tow for 2 hours, I had the gas cap open but still over tank hole. Over the first hour I tried starting the bike several times with a 5-10 minute wait between attempts with no result. In fact, almost completely discharged the battery I tried so many times.

The second time, after pushing the bike a mile I got to a hill (of course after pushing it up the hill!). I coasted down, popped the clutch, and it started right up. Stopped on the way home and filled the tank (all three times it happened at half a tank or little over).

The third time (today) I had just over half a tank. Started fine, got on the highway, drove about 1.5-2 miles and it started POOGSing. Had to pull over on the shoulder. Waited 5 mins with cap off and tried to start it. Nothing. Waited another 5 min with cap off and tried again. Nothing. Fortunately I was 1/2 block from a gas station. Pushed bike to it, filled it up and bike started right up. Drove it home another 9 miles with no problem.

cglennon I have not done your POOGS remedy procedure but I"m going to now. I really think my problem is the rubber vacuum valve inside the petcock (referenced above). If I have POOGS again after that then I will be certain that is the problem, so I'm going to eliminate the vent tube, vent holes and gas cap assembly first. Summer is ending here so that may do it, too. It's strange because I never had any problems with POOGS until I seafoamed the gas tank and my problem started the next day. Do you think it affected the rubber diaphram in the petcock to make it sticky? I know a lot of folks here swear by seafoam, that's why I did it. Kinda wished I hadn't.

In the meantime I will carry a 60cc catheter tip syringe to apply a vacuum to the petcock if it happens again. I'm convinced if I had one today I could have fired it up. My brake bleeder vacuum pump is what fixed it the first time. Don't know really though, not a mechanic, just trying to learn here like many others...:blah:

-jim
Jim,

Based on your description it does not appear that your bike is suffering from POOGS. POOGS, as it has been described on this site, is caused by a plugged or failed the gas cap venting system. The result is gas tank vacuum or excess pressure. The gas tank vacuum prevents gas from reaching the carbs resulting in engine stall. The gas tank excess pressure (i.e., bike parked in the hot sun for a long time) can result in the flooded carbs or fuel squirting out of places it should not (you did not mention flooding or gas leaking). Also, POOGS is very predictable; 1/2 tank of gas or less, engine stalls, open gas cap, crank, crank, crank, engine starts, close gas cap, ride for a few miles, engine stalls, repeat. In addition, POOGS won't leave you totally stranded, because you can just leave the gas cap open a crack to allow for proper venting.

Your description and work around suggests a failure in the petcock vacuum line or petcock diaphragm. The symptoms are similar to POOGS, but not as predictable. It is possible that the Seafoam loosened up some crud that is now gumming up the petcock, but I don't think that it damaged the petcock diaphragm directly (I use Seafoam in almost every tank full). Might I suggest;

  1. Perform the POOGS gas cap vent system cleaning as outlined in the original thread post. It only takes about 15 minutes and will potentially confirm or rule out POOGS as the source of the problem. Look for any blockage in the gas cap air channel and especially the very small vent hole.
  2. If the gas cap venting system is clear, then replace the vacuum hose leading to the petcock diaphragm and verify that there is indeed vacuum reaching the petcock (you seem to have a good handle on how to do this).
  3. If the above does not work, then drain the gas tank, remove, disassemble and clean the petcock and diaphragm. Replace any parts that appear to be faulty.
 

·
Linkmeister Supreme
Joined
·
7,960 Posts
I was out doing a little work on the bike today and decided to check the tanks vent and hose.
I tried blowing through the hose and listening at the open tank cap and heard zip, nada, nothing. Then tried sucking on the hose and heard nothing either. I didn`t pull the cap off to do the Poogs service outlined here yet, until I checked with some of you who have done this procedure.

Should I be able hear some air moving through the vent when blowing or sucking on it?
Or is the vent too tiny for the suction developed by sucking on the hose to be noticed?
 

·
Registered
Joined
·
738 Posts
Discussion Starter #16
I was out doing a little work on the bike today and decided to check the tanks vent and hose.
I tried blowing through the hose and listening at the open tank cap and heard zip, nada, nothing. Then tried sucking on the hose and heard nothing either. I didn`t pull the cap off to do the Poogs service outlined here yet, until I checked with some of you who have done this procedure.

Should I be able hear some air moving through the vent when blowing or sucking on it?
Or is the vent too tiny for the suction developed by sucking on the hose to be noticed?
If the gas cap is in the open position, then air should move freely through the gas cap vent tube. Otherwise the tube is blocked. If the gas cap is in the closed position, then NO. The only way you would hear anything by blowing through the tube is if the gas tank pressure was less than atmospheric (i.e., a vacuum in the gas tank). I only hear noise (i.e., whistling) at or below 1/2 tank of gas and sometimes just after filling up (i.e., the cold underground stored gas station fuel expanding in my sun soaked gas tank).

If you think that you have POOGS, then clean the gas cap venting system. It only takes about 15 minutes, a phillips head screw driver, a rag to cover the gas tank filler hole and some carb or chlorine free brake cleaner to flush the vent lines.
 

·
Linkmeister Supreme
Joined
·
7,960 Posts
Thanks Chris, that is what I thought. The cap was open, so either the steel tube or rubber hose is blocked.
Good time to clean the cap vent too. :)
 

·
romeobravo172
Joined
·
842 Posts
Am new to forum, have allready found many helpful articles about my 750, and am definately going to find out more, I am sure. My first battle so far has to do with fuel, ( petcock, or poogs ). Have disambled the pet cock, finding no noticeable problems,ie-trash/gunk or mystery stuf, to be on the safe side have ordered new parts just to be sure. I just bought the bike July 1st 11, 04-750a20 with 928 miles on it, common sense says it sat (in a garage for some time, hense gas gone bad) so gas problems is no surprise. Carbs disasimbled and cleaned, runs perfect till I get down below 1/2 a tank then--- will follow up with the vent cleaning (coming from Las Vegas mine is the cal version, 2 vent tubes off back of tank ). Thanks :beerchug:
 

·
Premium Member
Joined
·
4,765 Posts
I'd pull the CA emissions stuff off unless you plan to sell it to someone in CA. Heck, you could pull it off and keep it just in case.
 

·
romeobravo172
Joined
·
842 Posts
Poogs

Thanks Flight, What might be consecuences of removing the Cal emissions stuf, ie reset air fuel mix,stuf like that?
 
1 - 20 of 81 Posts
Top