I have a 1999 zx9r that has sat for about 4 years.pulled and cleaned carbs,replaced fuel pump.checked and cleaned spark plugs.it only runs when vacumn is pulled on carbs?

Sounds like fuel pump probs if you have no spark.

remove carbs and rebuild completely, old fuel builds shellac in needle valves and other ports. clean float valves thoroughly, and check choke for proper operation

Sounds like fuel filter problem, or bad gas which will cause fuel filter problems. Bad fuel will also carbon up the spark plugs and cause the engine to run erratically. Take a look at the plugs, they'll probably tell the tail.

hello sir, my machine will only start when pumping primmer bulb or squirting fluid in the carburetor than stops. the fuel line has broken off, in most small carburetors this is a ongoing problem.old fuel will crystallize when left in tank for a long time.plugging up ports, fuel lines, small screen in carburetor.fuel lines will dissolve clogging carb.this is why it will run when the choke is on creating a vacuum to where there is fuel forced in the carb to rum,also the gas will evaporate leaving the oil behind clogging up carb.the thing to do is remove carb. and clean out,replacing gaskets or fuel line if necessary.use carb cleaner to clean out carb.make sure to make note where fuel line go.the fuel filter broke off of fuel line letting debris get in carb plugging it up.the muffler is known to clog up a lot on these machines where they want run. the compression should be 60 to 120 lbs any thing below 60 is junk. when adjusting the carb screws turn in all the way than turnout 1 1/4 turns turn in slow until machine runs also you need to check for spark by removing plug and grounding against engine to check spark, ok.a new spark plug would be a good ideal too , if you are going to make these repairs use new fuel line and filter,hope this helps,any comments welcome,thank you, !!

check your compression, then make sure the fuel vac pulse line if it has one is not cracked, this creats vacumn when engine is rolled over which in turn pulses your fuel pump to pump fuel through carb. look in the spark plug hole with flashlite and look for scores in cylinder and piston, maybe remove muffler and look at cylinder with flashlite and make sure your rings aren't cooked to piston causing low compression. Sorry I got carry'd away, make sure your fuel filter is clean, fresh fuel and clean your carb and check diaphrams for being stiff if so replace them. Good Luck

Check if all of the plugs are getting spark. You can do that by pulling the high tension wire at the spark plug end and over the engine check if all are getting the blue arc. Check if the fuel filter needs changing. The fuel supply may also not be consistent, check during start up if fuel is being supplied to the lines via the filter or the hose to the engine also after the engine dies. Fuel may just be only at the start up and when idling supply is low or gone.
I am unsure if your year has the fuel pump already, it may be the fuel pump relay or the fuel pump has gone bad.
Try cleaning the intake with carb cleaners just to rule out dirt in the sensors and the manifold. Check for leaks in the vacuum hoses and air duct from the filter to the intake. It may also be the IAC valve or the EGR for the EFI variants, IAC especially if the idling after start up and before dying is rough. It may need cleaning or replacing.
If you still have the carb or it was converted to carb you may need to adjust the fuel and air by moving screws by quarter turns on the carb and taking note of the movements. It could also be the jets for the fuel which may need cleaning. Carb cleaner would do the job but for tough dirt you may have to remove the carb and clean the internals. During cleaning you may inspect the valves and the parts for wear.

Basics to check:
1) Spark plug - brown or dark brown - OK
a) is it carbon or fuel fouled
b) is there spark

2) Muffler remove for inspection
a) exhaust screen clean or plugged
b) inspect cylinder wall/piston as the flywheel is slowly rotated
3) Check cylinder compression


Fuel starvation - 'lean fuel' condition
Basic things to check:
1) spark plug
2) spark arrestor in muffler
3) fuel lines and tank filter
4) turn adjustment needles out (counterclockwise) 1/4 to 1/2 turn
Chain Saws:
5) check impulse tube and intake boot for cracks or leaks
*if all of the above are OK and/or do not improve performance then:
Remove Carburetor
6) replace gaskets/diaphragms
a) use a spray carb cleaner to clean jets, holes, and body of carb
b) fuel pump diaphragm goes against the carb body,
then the gasket towards the outside
c) metering gasket goes against the carb body,
and the diaphragm goes towards the outside

I’m happy to assist further over the phone at https://www.6ya.com/expert/rolandw_c013176d62ee17ae

If no fuel stabilizer was added while the bike sat for a year or so.
It is most likely bad fuel with gum deposits.
This can can create some problematic symptoms for you.

It is vital the bad fuel to be cleared from tank/lines and carbs.
You may need the fuel system cleaned as the gum deposits can cause major headaches in the carbs and jets. If the system is not cleaned and even after you get the bike running, you could be miles away and have the fuel fowl jets/injectors, causing shut down.

Check the spark plugs carefully. Oil on the plugs may just need cleaning. Once you get the bike running the oil should burn off if the rings are still in good shape.

Motor needs clean Air, Clean Gas and a hot spark.

Good luck!

Check compression ratio and valves clearance.The carbs leak any fuel from their o-rings.Spray through the air box with a carb cleaner spray while pressing start button but little bit at a time.Don't twist the throttle too much and always use choke until she fires up for good.

hi remove the spark plug and pour a tea spoon of fuel into where the spark plug goes then put the spark plug back and try that