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Discussion Starter · #1 ·
ok i have been messing with this for two days and quite frankly i am just so pissed i am ready to light this thing on fire and and watch it burn.

So here is what i have. I pulled the fuel tank and replaced the fuel pump because it was bad. While i had the fuel pump out i replaced all the fuel lines and the fuel filter. Now i have tried to just turn the bike on and the fuel pump did pump and stopped but there wasnt much fuel in the fuel filter, so i wired the fuel pump directy to the battery and it didnt start pumping but was on. So i was confused. I opened the bowl screws and no change. When i try and start it the bike will try and fire but wont fully start. When i put a little fuel in each of the carbs, it will runs for about 30 secs with full choke.

i am pretty mechanically incline but this has me stumped. it ran just fine before i changed the fuel pump went bad. i have checked all the hoses to make sure it is all hooked up right and i just dont know what else to try. Its only been 2 days since it last ran.

oh btw it is a 93 zxr750L. Any help would be appreciated, and sorry for the poor grammar and mispelled words. i am just really upset with it.
 

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Discussion Starter · #2 ·
No one??

ok this is what i have done today so far. I open the fuel bowls again and bleed all the air out of the system. I then also pulled all the spark plugs and they all look new but had some black on the ends. Cleaned all the black off and i am leaving the cylinders open to help air out any fluids still remaining in the cylinder.

I will keep everyone updated on what i find.

If anyone has anything to throw in please help. I was looking forward to riding today since it will be 50+ degrees.
 

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Keep in mind the fuel pump is self regulated to 3-6 psi. So once it builds up pressure it stops.

Also, the fuel pump runs off the ignition coil pulse thru the fuel pump relay. If the pump won't run while cranking (the ignition is bypassed during crank) you have to look at the junction box as the culprit as there is an internal non-serviceable relay inside for the fuel pump.

Beyond that, make the lines are not kinked or cramped in any way. It's very easy to pinch a line installing the tank.

Also, make sure the petcock is actually turned to ON or RESERVE and not actually turned off.

Also, since the filter is BEFORE the pump if it isn't filling with fuel then the problem lies elsewhere (i.e. between the tank and filter), not the pump.

Josh
 

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That relay can be easily replaced by someone who knows how to solder on PCBs btw.

In fact, if you are really good at it, it can be done in about 5 minutes.

And if you are even better, you solder in a socket-type relay that can be replaced easily the next time xD
 

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That relay can be easily replaced by someone who knows how to solder on PCBs btw.

In fact, if you are really good at it, it can be done in about 5 minutes.

And if you are even better, you solder in a socket-type relay that can be replaced easily the next time xD
He can't simply get his bike to run, you think he is going to solder on a PCB? :evil

Josh
 

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Discussion Starter · #6 ·
**********UPDATE***********

Ok so instead of waiting for the spark plugs to dry out, i just bought some new ones. i replaced the plugs and it fired up. OK so now i have another problem. I can get it running by giving it gas and keeping it at 3-4k but once it tries to idle down to 1k it will die every time. I have let it run for 20 mins and still dies. I also noticed that the throttle response is really weird. When i give it gas it takes forever for the rpms to come back down. I have lubes the cable and links but no change. i have tried to use carb cleaner in it and i let it sit for about 30 mins. Still no go, i am stumped again. I feel like i go two steps back just to go 1 forward. I just don't get it, it ran fine before i decided to replace these parts to make sure i wasn't stranded on the side of the road this year.

any help would be appreciated.
 

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Idle hanging up is a lean issue and usually from a vacuum leak.

As for actual idle RPM, it should be set 1100+. I set mine around 1300. My bike is tuned really well and there is no way it will idle at 1000.

Besides the fact the factory spec is 1200 +/- 50 rpm.

Josh
 

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Interesting Symtons... The Black plugs were Carbon fouled, which is a sign of too rich... Throttle hanging like Bullitt says a vacuum leak, or major sync problem. Now if she is not idling, you need to pull the pilot jet out (next to the main jet down in the hole) and run a strand of electrical wire through them. They control the fuel below 3k.

When all else fails, buy 4 economy Carb rebuild kits, and clean every aspect, run a strand of electrical wire through the Main jet holders (3 little holes on 4 sides), clean clean and clean until you are sure they are clean, then clean 2 more times. Just a guess..., Good luck brother
 

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Discussion Starter · #9 ·
Thank you for all the info. I am going to take a day or two break from it. I tried to spray starting fluid all around the carbs and vaccum lines but no surge. So i guess i will be looking more into this. I did try and take the carbs off cause i had to replace the cam tensioner, but i never got the off they were stuck. I was only able to break them free a little and wiggle them.

Can this cause the carbs to loose sync??
 

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Thank you for all the info. I am going to take a day or two break from it. I tried to spray starting fluid all around the carbs and vaccum lines but no surge. So i guess i will be looking more into this. I did try and take the carbs off cause i had to replace the cam tensioner, but i never got the off they were stuck. I was only able to break them free a little and wiggle them.

Can this cause the carbs to loose sync??
Those screws you loosened to get the carbs to wiggle, those are the same four phillips screws that need to be TIGHT, that is normally where the vacuum leak is. But it has nothing to do with the carb sync.
 

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It's pretty easy when tightening the carb boot clamps to cinch the throttle arms with the springs into the rubber... Making the throttle return lazy or slow

Been there done that...

Josh
 

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Discussion Starter · #12 ·
***********UPDATE**************

Thank you everyone for all your input. It has been a real big help. I got some time free last night and decided to work on the bike. SO i went to the garage and pulled the carbs completly off and took them inside my warm house lol. Anyways after removing the bowls and finding shit caked to the bottom i decided to dig deeper, found the main jet and pilot jet were clogged and carb 4 has chunks of crap around it and in it. Yeah so after 4 hours of cleaning and soaking parts, i put it all back together and remounted to the bike, turned the fuel on, primed the carbs, and hit the start button the bike fired up. after 3 mins and warming up turned choke off adjusted the idle screw and it is now idling at 1200-1300 rpms. Runs smoother and better then before i took the take off.

Throttle cable still sticks a little and the carbs seem slugish sometimes but i am gonna run it to the gas station today fill it up and add some seafoam to the tank and just run it and see how it does.

So thank you everyone for all your help. If you are in the central illinois area contact me and we will go for a ride.

i will be upgrading my headlights to clear lenses with some 8k hid's. i will start a new thread for that. :)
 

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Check to make sure the throttle cables are not bent. My cables stuck like crazy, turned out I just bent the shit out of them while I was fighting with them. After taking them off the bike completely (really easy btw) I learned to take the grip apart instead of trying to bend them off the carbs.

Straightened the bends in the cables out and lubed the hell out of them, and now its smoother than it ever was.

If you ever come up to the Racine, Kenosha, or Milwaukee areas let me know and we can go for a ride xD
 

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..... I learned to take the grip apart instead of trying to bend them off the carbs.

Straightened the bends in the cables out and lubed the hell out of them, and now its smoother than it ever was....
The Gospel of Masta Squidge has been spoken, heed his words, and tho Throttle Cables shall be saved!!!
 

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Discussion Starter · #15 ·
so after taking my bike out for a ride today after i returned home it was acting the same way. So i let it sit for about 10 mins and then came back out tried to fire it and nothing gave it a little gas and she started. rev the motor and it only returned to 4k and now i am back to where i was before. WTH!!!??!?!

i am at my wits end and i have about had it. I spayed some carb cleaner around the boots and nothing. i cant find a vaccum leak anywhere.
 

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so after taking my bike out for a ride today after i returned home it was acting the same way. So i let it sit for about 10 mins and then came back out tried to fire it and nothing gave it a little gas and she started. rev the motor and it only returned to 4k and now i am back to where i was before. WTH!!!??!?!

i am at my wits end and i have about had it. I spayed some carb cleaner around the boots and nothing. i cant find a vaccum leak anywhere.
What do your Plugs look like?
 

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Those look pretty good.have you checked the slides to make sure they are coming all the way down? I know my number three hangs a little and I have to blip the throttle to get it closed again.
 

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what do the center electrodes look like, you cant see them in the pic...
 

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what do the center electrodes look like, you cant see them in the pic...
+1 We need a straight on picture of the bottom of the plugs looking into them. Think Hustler,not Playboy.
 
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