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mis-firing VZ800

16411 Views 15 Replies 6 Participants Last post by  trj2222
I have a 2000 VZ800 Marauder that is mis-firing on the front cylinder only. I switched the coils and the front cylinder still has an irradic mis-fire. Test light hooked to the spark plug wire shows it is only firing about 50% or less of the time vs. the other cylinder. I suspect it is the CDI box or a short in the wiring from it. How can I check the CDI to determine if it is the culprit? Any other suggestions that may cause this firing problem would be appreciated. Thanks, Stan.
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2000 suzuki marauder vz800

I recently purchased a 2000 suzuki marauder vz800 that has been sitting up for 8 years. The fuel pump wasn't working. I took it apart and lubed it with royal purple over a couple nights and voila the pump started working on its own. I also took out both carbs and cleaned thoroughly (even though they looked great on the inside). I started up the bike and it ran for a short 5 minutes or so before it clunked out. Ever since then, it has trouble restarting and when it does it dies shortly after and i notice that the front cylinder is not firing or if it does, its only 50% or less of the time. I have plenty of fuel and have already checked the plugs, wires and coils. I am going to look into getting the cdi replaced and get the results out on the web for the next guy. Then more than likely i will need to check into stan's carb adjustment for an oversight of what mine should be at.
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Thanks Easy rider. I am new to forums and motorcycles! I am not sure how to test the fuel pump. I have the gas tank on a table next to the bike, i have the main and reserve hoses connected to the petcock (with the petcock set to on) and another hose connecting petcock to the fuel pump. i have the hose from fuel pump to rear carb disconnected and i crank the motor over and fuel is pushing out of the pump at what i think to be a decsent amount. i reconnect the hose to the rear carb and pull another hose from the rear carb to the front carb off and fuel is pushing out of the hose going to the front carb. so i am pretty sure the pump is working but volume... I dont know??? i cant find any info on what the psi should be for the fuel pump suction and output (not even documented in my owners repair manual). which is funny you mention the fuel pump integrity because after i posted that thread i went back to tinkering on the bike and when i inject brake cleaner into both carb vent ports the bike starts and runs on both cylinders (for the most part). It still sounds like it might need some tweeking and i am not sure for how long it will run but both cylinders are firing off and the front cylinder exhaust gets very hot!! I will post my findings as i progress. Have you had this problem before? and am i on the right track?
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yes the choke cable is pulled/ engaged when i try to start it...
when i drain the carb bowls, they both release fuel...
i was thinking fuel delivery issue also since i can fill both carb vents and it cranks up beautifully and fires on both cylinders (both exhaust pipes get hottt!!) *runs a little rough though like the carbs air/ fuel mixture needs to be balanced/ sync'd.
but like i said earlier, i know the fuel pump is pushing pretty well to both carbs but volume or psi??? not sure... i have an owner's manual but it doesn't document the fuel pressure psi specs for the input (suction) or the output psi. and i can't seem to find that info on the web.
Ok small update: the bike will not start up on a cold start unless i insert brake cleaner/ quick start fluid into the rear carb vent tube. then if i can keep it alive until it idles on its own (usually about 5 minutes or less) it will run fine all day and even idle fine. i can turn it off, come back out after over an hour and it will still start right up on its own. but again, if it sets over night, the next day it will not start up on its own. not sure why this is but as long as i have some quick start fluid, i have little to no worries about driving this machine all over the city.
ohhh and i notice it starts up a lil better without the choke upon cold start up
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