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Discussion Starter #1
Hi,
I just joined, Thanks for having me.
I need help on this one.
A friend rode his bike up and asked me to paint it for him, which I did.
When I finished, I went to start it and it ran fine for a few seconds, but then died.
I’ve switched out the module, coil, cam timing sensor, bypassed the kill switch, just about everything you can think of, and stil same thing.
The carb is squirting fine, and has spark, and will immediately fire back up, but then die.
Any ideas? Any help would be greatly appreciated,
Thank you in advance for your time,
John
 

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Would assume you took the tank off to paint. What type of bike and what type of petcock? Are the vacuum lines hooked up correctly? It ran before the paint job, probably something simple.
 

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Discussion Starter #4
Stock carb?
Will it stay running at idle without throttle?
Yes, its a stock carb, it’ll idle fine, and will rev up fine, but after a few seconds it just dies.
but will start right back up, if you turn the key off, then turn it back on.
 

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Discussion Starter #5
Would assume you took the tank off to paint. What type of bike and what type of petcock? Are the vacuum lines hooked up correctly? It ran before the paint job, probably something simple.
Yes, I took off the tank.
it’s a pingle or however you spell it, high flow petcock, I checked for flow and it was good.
Right after the bike died I turned the gas off immediately and pulled the bowl off to also check it, and it was full of gas.
 

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u must be running the bowl dry...how long is a few to u ...how many is that seconds?..2?..3?.. or 20 or so?...it runs for then cuts out?...or no venting to let fuel thru
 

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Discussion Starter #7
u must be running the bowl dry...how long is a few to u ...how many is that seconds?..2?..3?.. or 20 or so?...it runs for then cuts out?...or no venting to let fuel thru
It will run fine some times for 2-3 seconds, 15-20 seconds to max 30 seconds.
I checked to see if it drained the bowl a couple ways.
I took the air cleaner off and it was still spraying when it died.
then with it running and my hand on the petcock, I immediately turned it off when it died and pulled the bowl, it was full of fuel
 

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Discussion Starter #8
It will run fine some times for 2-3 seconds, 15-20 seconds to max 30 seconds.
I checked to see if it drained the bowl a couple ways.
I took the air cleaner off and it was still spraying when it died.
then with it running and my hand on the petcock, I immediately turned it off when it died and pulled the bowl, it was full of fuel
No sputtering, just flat dies like someone hit the kill switch
 

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offhand i would go with fuel related,, it qouldnt stop running in that short amount of time if it were no vent... the squirter is just the accelerator pump, has nothing to do with idle or high speed,, just a squirt of fuel to fill the void created when the throttle is opened.. i would say,, either a low speed jet air passage is clogged, or a low speed fuel passage,, in the carb body,, probably due to dirt in the air qhile the tank was off.. if ir is a keihin butterfly only carb, there is a rubber plug that is in the hole that the low speed jet screws into, after the jet..

look into those and get back to us.
 

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gotta be fuel..unless your fuses are funky...yeah jets/carb are next to check....or something electrical is failing quickly and resetting quickly...chk the leads on the coil too/tank removal....check all elec conns...while back .i had a rotten fuse that looked good on a metric bike that almost drove me wacky....was not letting fuel pump perform well
 

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Discussion Starter #11
offhand i would go with fuel related,, it qouldnt stop running in that short amount of time if it were no vent... the squirter is just the accelerator pump, has nothing to do with idle or high speed,, just a squirt of fuel to fill the void created when the throttle is opened.. i would say,, either a low speed jet air passage is clogged, or a low speed fuel passage,, in the carb body,, probably due to dirt in the air qhile the tank was off.. if ir is a keihin butterfly only carb, there is a rubber plug that is in the hole that the low speed jet screws into, after the jet..

look into those and get back to us.
Thanks, I’ll try the jets.
but what I meant was when the bike is on the lift, and I have the air cleaner off of it, and it’s being running at high rpm and dies. I hit the throttle and see the gas squirting in and still the bike still dies.
im not a mechanic but I’ve been building Harley’s my whole life, 64 now and I can’t figure this one out, it’s killing me. I’ll try the jets now. Thanks
 

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check the jets,,, but more importantly the passages that feed the jets fuel and air,, and also to where the fuel exits when entering the intake manifold. the ports on the far side of the throttle plates,
 

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Discussion Starter #13
gotta be fuel..unless your fuses are funky...yeah jets/carb are next to check....or something electrical is failing quickly and resetting quickly...chk the leads on the coil too/tank removal....check all elec conns...while back .i had a rotten fuse that looked good on a metric bike that almost drove me wacky....was not letting fuel pump perform well
Hi, Thanks, I’ve checked everything electronically, including swapping out the coil.
the good news is I have that many spare parts between my friends and I so no cost other then the cam sensor/ timing.
min going back out to see if I have a spare carb or check this one out. Thanks
 

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Discussion Starter #14
Ok. I went over the carb real good, and just to be safe, I took the carb off my 2000 Dyna and does the same thing.
I’m to burnt and mad to put anymore work in it today.
Thank you to everyone that’s helped, if and when I get it running I’ll let you know what the culprit was. Thanks
 

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One of my questions was will it stay running without throttle?
I mean KEEP running. No throttle. For as long as it can until you turn off ignition. If yes, than it's the carb.
Otherwise I would check your wiring under the tank. Particularly the kill switch wire. I had an issue there on my '90.
Did you have the handlebar controls apart? The switches can go bad.
 

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Unplug the connector for the right hand controls, make sure the contacts are ok, and not pushed back out of the connector, the white wire is the one that sends power from the kill switch down to the coil and the module.

Connect your voltmeter to the white wire, and start the bike, read the voltage and see if it changes when the engine quits.
 

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yeah... kill sw goes funky dirty alot mine did on both my bikes.....tore the bike it half apart one day on the road only to finnally jump the kill sw and fixed it.
 

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Discussion Starter #20
One of my questions was will it stay running without throttle?
I mean KEEP running. No throttle. For as long as it can until you turn off ignition. If yes, than it's the carb.
Otherwise I would check your wiring under the tank. Particularly the kill switch wire. I had an issue there on my '90.
Did you have the handlebar controls apart? The switches can go bad.
Hi, and sorry it takes so long to answer. I’m so busy I. Arely have time to sleep.
but no, it’ll idle perfect, but die in 20-30 seconds.
the one thing I’ve noticed isafter it dies, it will not start, unless you turn thekey to off and then right back on and it will start right up.
but only if you turn the key to off right when it dies then immediately turn it back on and it’ll fire back up and do its few seconds and die again I did that about10-15 times and it worked every time. Just keeps dying though
 
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