fuel pump/ carbs issues

Cusimano · Apr 5, 2013

I haven't posted much in the forums but I do read a lot of the helpful posts here. Wanted to say thanks yukonerdave for the awesome write up on the fuel pump diaphragm fix, and richwrench for the carb sync tool its awesome and works great. Here's my problem I have an 88 vmax it fires up descent however the fuel pump noise does seem to be long even after the bike is warmed up. If i turn it off it still makes the noise as soon as I turn the key back on, and its not a short noise still 6-7ish (and no I'm not using a stop watch just going by what feels excessive=) even with it warmed up and just turn off then on. The other issue is, I can only go down the road a block till it feels like its running out of gas (and no its not out of gas =) then just stalls, and will not start for over an hour. When i look at the fuel filter it doesn't seem to be pumping gas into it fast just a squirts and a quarter of the filter stays full. Also I have done the shotgun cleaning of the carbs. I feel the fuel pump is going bad but this is my first bike with a fuel pump so I'm not sure how it should be running. Any help would be appreciative Thanks.

one2dmax · Apr 5, 2013

Just flat sounds like it could be worn out. BUT, one thing to for sure check is that it is not sucking air in the line from somewhere between the tank and the pump. This will not let it properly build pressure. The smaller the air leak the harder it is to find the problem. You can by pass all the OEM lines and simply try a new section of fuel hose from the tank to the pump and see what that does.

Cusimano · Apr 5, 2013

Thanks ill check that out.

I forgot to ask for help with syncing the carbs. At first cyl 2 pulled hard then I tried to make adjustmente and now cyl 3 pulls real hard. And I forget how I had it. I fired the bike up adjusted to were it sounded better bit cyl 3 still pulls hard. Any way for a base to start from?

wildweasel_pt · Apr 5, 2013

You know theres a search option above on the menu bar? Theres also service manuals surfing the web... www.vmaxoutlaw.com

http://www.vmaxforum.net/showthread.php?t=3959

Cusimano · Apr 5, 2013

Cusimano said:
I haven't posted much in the forums but I do read a lot of the helpful posts here. Wanted to say thanks yukonerdave for the awesome write up on the fuel pump diaphragm fix, and richwrench for the carb sync tool its awesome and works great. .

Sorry I missed the and all the stickies are helpful too.

Yes I've seen...and used the search button thank you for your help in locating it.

Cusimano · Apr 10, 2013

Since its my first time attemping syncing a 4 carb bike. I built that sync tool with atf in it. Is it best to start with the left side hooked up to the carbs only and one its adjusted disconnect the left side, move to the right only then hook both sides to balance,or do you have to have all 4 connected to the carbs to start syncing.

davesax36 · Apr 10, 2013

Hook them all up. And make sure you put some tiny reducers in there near the carbs. If you don't, you'll be sucking atf into the motor.

I do 1-2, then go do 3-4,then match the sides.

Sent from my Galaxy Nexus using Tapatalk 2

95spfldmax · Apr 10, 2013

On the fuel pump....

If it's working properly, you should be able to turn the key to run, the pump should click and "eventually" stop, you should then turn off the key then back on, and prob do again without ever starting the bike and the pump should finish click/pumping up and hold pressure. It should reach max pressure and shut off. See if this is the case.

Otherwise one other possible prob is you may be fuel starving from a pinched vent tube. From recently overhauling my bike, when I pulled the vent tube out of the springy thing under the motor I was surprised to find the end of my hose pretty much pinched closed. I'm unsure how this happened and I believe it was affecting my performance at high speed (felt hesitation/skipping feeling) unlike your symptom more at lower speeds but still could be a problem. It's something to rule out anyways.

Hope this helps.

95spfldmax · Apr 10, 2013

davesax36 said:
Hook them all up. And make sure you put some tiny reducers in there near the carbs. If you don't, you'll be sucking atf into the motor.

I do 1-2, then go do 3-4,then match the sides.

Sent from my Galaxy Nexus using Tapatalk 2

+1 for sure. Otherwise you waste too much time unplugging and plugging up the unused vacuum connections. And you prob have to go around the above mentioned loop a few times to get it just right........

fuel pump/ carbs issues

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