Fuel pump constantly running

[infinity999]

Nope, never any flooding externally. I just hooked up carbs 3 & 4 individually and of course it takes a couple of key cycles to fill up the bowls. After that I can turn the key on and off and the pump isn't running! Now I'm confused. Maybe it's one of the hoses doing something weird? I did hook up a different line from the pump to the carb.. I also hooked up carbs 1 & 2 (together). The bowls fill, then if I cycle the key the pump doesn't run again. Maybe it is an air leak in one of the lines? Or the line that goes from the pump to the carbs. Guess I should go buy some clamps..

interesting diagosis technique.... cool well have u determined its not shutting off fuel mean it is overflowing.....is it flooding at idle with fuel pissing out of carbs ??????? u never mentioned its flooding externally yet.....

 

[infinity999]

Well I finally go the carbs back on the bike and fired it up. Did a sync and everything seemed fine.

Then I decided I would pull out my long screwdriver again and have a listen to the pump. While idling I would hear a click every couple of seconds. Then gradually as the bike started to warm up the clicking got faster and faster until the pump was constantly running again while idling! So I immediately shut the bike off and cycled the key a couple of time. Both times the pump through the full 4 or 5 second cycle. I then went around to each carb, hooked up my clear plastic tube and opened each drain screw and cycled the key and the level didn't change. Seems that the pump is always running on the key cycle, but isn't really pumping any fuel. So I let the bike sit for about 20 mins. Came back out, turned on the key and only a couple of clicks. Fired the engine back up and the pump was only clicking every couple of seconds again. Sure enough, the clicking started getting faster and faster until the pump was just constantly running during idle. Is the pump defective? I opened the pump up a couple of weeks ago but did not see this infamous diaphragm floating around inside. Also, I hear the relay could be defective, but wouldn't the pump not run at all if that is the case?

The other odd thing.. When the pump starts acting up, I can take the fuel line off the carbs and place it in a bottle. When I turn the key on, the pump seems to sputter a little bit of gas out and then starts pumping a large amount of fuel. I can then hook the line back up to the carbs cycle the key, and it maybe clicks once. Possible air leak in the line? Not sure. I have not yet replaced the line running from the tank to the pump, only the pump to the carbs. If it were sucking air, I wouldn't think it would be intermittent..

 

[johnpclynch]

Maybe the pump is building up an air lock, check the line from the tank to the pump. Make sure no air is getting in. I had a pinhole in a filter once and the pump would suck air in through it but fuel would never leak out

Ever try drink through a straw with a hole in it?

 

[infinity999]

Yes, you could be right. I just ran the bike again and the pump seemed fine, then as the bike idled the pump started constantly running again.

I then shut the bike down, took the fuel line off the carbs and put it into a glass. Turn the key on and the pump started sputtering fuel, then after a few seconds a constant stream. Can an air pocket really build in the system? Is that even possible? After I connect the line back up to the carbs it seems fine again.

 

[infinity999]

So I replaced the line from the tank to the pump and bypassed the filter. Started the bike, listened to the pump and it sounded normal. Even after the bike was fully warmed up and the fan kicked on, the pump was still only clicking about once a second or so. Looks like I may have found the problem. But, which hose was is the problem? So I hooked up the new line to the outlet of the fuel filter, and put the old u-shaped line in that goes between the tank and the filter. Fired the bike back up, and sure enough, it took a minute or so, but the pump gradually starting clicking faster unit it was running continuously again! There doesn't appear to be any visual damage to that hose, but it has to be leaking someplace and sucking air. So I replaced that small hose with a section of new hose and that seems to have fixed it.

Also, once air gets trapped in the line, it is necessary to disconnect the fuel line from the carbs then run the pump to let the air out. Air seems to get trapped in there! I'll report back if anything changes, but this looks promising, finally!

 

[alorio1]

If I were you I would check the vent line off tank and the tip over valve also. Blow some air thru the fuel inlet and the vent off line of your tank to clear any obstructions there also. My inlet was plugged one time and I had to blow air thru it to get whatever it was dislodged. I never found what the forein object was, but my fuel pump was acting simular to what you are describing. Most members find their vent line obstructed and the fuel pump will pull fuel untill the vacum on the tank overcomes the pull from the pump, then engine dies and pump is still running but can't pump because of vacum in fuel tank.

 

[infinity999]

The vent tube is totally clear.

Since replacing all the line, and putting the fuel filter back in the line, if I cycle the key the pump seems to running longer than it should. Also, I just got it to run continuously with the bike idling. After a minute the pump calms down to a click every second or so. I can't believe the fuel filter is sucking in air, I just changed it! Also, I'm not able to clamp down the aftermarket hose between the tank and filter because the factory clams won't fit, but the connection is very tight. Maybe not tight enough?

 

[johnpclynch]

My fuel filter was also new, they used hot glue to stick it to some packaging and that melted the case a fraction

You could also try reshape the factory clamps in a vise so they will clap down a bit more?

 

[tugla]

What is the spec for amount of clicks per sec while running you are referring too....couldn't find any in book.

So with proper fuel line size and clamps there shouldn't be sucking air issues ....one would hope....

 

[johnpclynch]

There is breif description under FUEL PUMP SYSTEM in the Service Manual with a table which translates into...

Pump START for about 5 seconds when carburetor fuel level is low:
- Main/Engine stop switch turned to "ON"
- Fuel reserve switch turned to "RES"
Pump START after about 0.1 second:
- Engine turned on
Pump STOP after about 30 seconds:
- Fuel warning indicator light comes on
Pump STOP after about 5 seconds:
- Engine turned off

 

[tugla]

ya nothing more about the clicks while engine running and not on reserve......I would think as it idles and runs the fuel level drops pump turns on so this constantly happens. so how many clicks is too much clicking....I hear mine going.....bikes run fine ???????

 

[infinity999]

Well, when it's idling and not having any issues (like sucking air) I would say it will click about once a second or so. Sometimes a little quicker, sometimes a little slower, but I don't think the pump should be constantly running when the engine idling. I doubt there is any published spec. on this.. Kind of interesting to listen to while it's running if you've never done it before.

 

[tugla]

Yes I have and didn't find it unusual that it was clicking while running. Your fuel switch is set to the right on the ON poss correct? And not to the RES side which forces the pump to be on all the time.

 

[infinity999]

Switch is definitely in the ON position. I didn't think switching to RES. would make the pump run constantly, I read here on the forum that it makes it operate when the low fuel light comes on, because it cuts off when there is low fuel in the ON position. Why would it need to run constantly in RES.? It would just need to function normally right?

 

[dannymax]

Yes I have and didn't find it unusual that it was clicking while running. Your fuel switch is set to the right on the ON poss correct? And not to the RES side which forces the pump to be on all the time.

Checked this on Memax yesterday Rov, pump seemed to click about every second whether on RUN or RES. :confused2:

 

[tugla]

Checked this on Memax yesterday Rov, pump seemed to click about every second whether on RUN or RES. :confused2:

Well......so seems regular interval of clicking is normal....

 

[infinity999]

Well I replaced all the lines and fuel filter going from the tank to the pump and the line to the carbs. The fuel pump would still start to constantly run when the bike got hot, and you shut the bike down, cycle the key and it would constantly prime. If you let the bike cool off for a bit, it would eventually build pressure and the pump would shut off. So I bought a new pump and still have the same problem! With the old pump, I could disconnect it from the carbs, cycle the key, some fuel would sputter out and then there would be a constant stream. Seemed that air was getting in the line causing the pump to have a hard time sucking fuel.

So if I replaced all the lines, and even the pump, where could it possibly be sucking air from? I haven't checked it yet by removing the line from the carbs and cycling the key with the new pump, but I imagine the results will be the same. Also seems odd that it only occurs when the bike is hot. I checked the vent line and I can blow through it. Could it be some issue with that valve that shuts off fuel in a rollover? Sucks that I may have wasted $200 on a new fuel pump I didn't need, oops..

 

[naughtyG]

My 2000 suffers from the 'way too much clicking everytime I switch on'. Then again, I know my lower rubber boots (between carbs and vboost valves assembly) are shot, and I sure am hoping that is the air leak that precludes the pressure from building up in the bowls and stop the pump as it should.

Maybe you have a similar problem? Did you check all your carbs rubber boots are air tight?

 

[infinity999]

My boots all look ok. The fuel pump seems to only constantly run after the bike has reached operating temperature. Guess I could spray some carb cleaner around the boots and see if that affects the idle. I also get quite a bit of backfiring on deceleration that it never used to have.

Did you actually verify your boots are cracked? I have spent quite a bit of money already throwing parts at it and really don't want to buy the boots if I don't need them. I do live in Vegas where it gets very hot and it's a dry climate. That combined with the bike being an '03 could be the issue, just not sure.

Also, the bike is still idling on 3 cylinders at all time. I can run the mixture screw all the way in on carb #4 and it does nothing to the idle. Turning them in on all of the other carbs makes the engine stumble. I can put my hand over carb #4 and feel a strong vacuum and it will cover my hand with fuel. I am definitely getting spark on this cylinder. Carbs have been gone through several times and the floats have been set.

 

[naughtyG]

I know one of my lower boots is broken - it's split and has a piece missing. I've just not got round to swapping it yet as I need to pull the whole motor and split the cases to fix 2nd gear anyway..
BTW I also get popping in the exhaust on desceleration on this 2000, I'm hoping it's related!