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I was riding and my 2003 Honda Shadow Ace started sputtering until it died. It was acting like it’s cold or ran out of gas. I can start it with the choke out but it really doesn’t want to. As soon as I touch the throttle it dies. I’m told the whole fuel system is new including fuel pump and the carbs were cleaned shortly before I bought the bike (9 months ago?).

I brought the bike to a mechanic and he cleaned out the fuel line and flushed the carbs. He said the bike looked beautiful and he found nothing wrong. The bike starting running beautifully.

I picked the bike up and rode the bike yesterday for 70 miles with no issue. but today the same thing started happening. it began sputtering at around 20 mph and then kicked back in with power. this happened 2x. then at around 45 mph bike lost total power and died. i pulled over on the side of the road and it wouldn't start. messed with the choke and turned petcock off/on/reserve over and over and over and finally started and got power. i rode 1/4 mile and then died again. it wouldn't start. i then messed around with the petcock again and the bike turned on and had full power. the mechanic wants to change the petcock but the guy i bought the bike from changed it out 15 months ago with the OEM part..

Here's a video of me on the side of the road after i was able to turn the bike on

 

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1983 Honda vt750 Shadow
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Easy test of fuel in the carb is to loosen the drain screw near the bottom of the carb and see if 1 or 2 ounces of fuel runs out.
If not the fuel delivery system is failing you.

Even If all that is new maybe the tank had a lot of rust and has clogged the new parts???

Some guys have had carb icing now in this winter weather, maybe that is it.
Look into the carb throat when that happens to see if it has a ice build up inside.
 
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Discussion Starter #3
Easy test of fuel in the carb is to loosen the drain screw near the bottom of the carb and see if 1 or 2 ounces of fuel runs out.
If not the fuel delivery system is failing you.

Even If all that is new maybe the tank had a lot of rust and has clogged the new parts???

Some guys have had carb icing now in this winter weather, maybe that is it.
Look into the carb throat when that happens to see if it has a ice build up inside.
I'm in Florida and I've ridden the bike for 8000 miles with no problems at all. This is a sudden issue. Right now the bike is starting up with no problem and has plenty of power when i hit the throttle. It just seems completely random.
 

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You might try the fuel in the bowl test, just in case there is an intermittant fuel pump problem.
A weak failing spark will act like out of fuel too. if there is a heated electrical component problem.
Check your battery terminals for clean and tight.
Also check the 3 yellow wire connection going to the voltage regulator. It is a weak spot that gets hot and lowers the charging voltage.
 

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Discussion Starter #5
You might try the fuel in the bowl test, just in case there is an intermittant fuel pump problem.
A weak failing spark will act like out of fuel too. if there is a heated electrical component problem.
Check your battery terminals for clean and tight.
Also check the 3 yellow wire connection going to the voltage regulator. It is a weak spot that gets hot and lowers the charging voltage.
a friend suggested checking the battery terminals but i was unsure why. i don't feel like it could be a battery issue.
Thank you for your help.
 

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So many guys have gone in circles just to find out a poor connection at the battery or the battery itself has been the problem all along.
If it cranks well even when it won't run right, it is probably OK, but check into it to make sure.
Check the charging voltage by revving up to 3000 RPM and see if it charging around 13.5 to 14.5 volts.
 

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Have you considered maybe an electrical problem within the ignition system. If you determine it's not a fuel problem, I'd look at the ignition coils. I've seen these coils test good when cold but as they heat up, internal resistance builds up and they either put out a weak spark or no spark at all until they cool off again.
Good luck,
Phil
 

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Had a similar issue when my carbs were rebuilt.
Mine ended up being the tank vent hose was getting crimped and not allowing air to flow into the tank.
I re-routed the hose, blew into the hose to make sure it was getting air, problem fixed.
 

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Why not bring it back to the mechanic you paid to investigate the problem?
This is my thought too...
When I spend $$$ at a shop, I kinda expect some kinda Warranty on their work...
When my Three Yellow wires connector did finally give up, the Bike ran really rough, almost like you describe...
I pulled into the gas pumps and examined things when I found it...
I`m with ya @gdb069
Dennis
 

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It's hard for the tech sometimes to replicate the intermittent problems, not defending him, just saying they often just hand it off to you the second things seem to be ok and it's on to the next. I second the thought of battery cables, doesn't hurt to clean the connections and rule that out. I would pull the main line from the tank and see how much fuel is flowing out into a cup in ON position and RES, then look at the quality of the fuel, check for water separation. Do you always fill up at the pump or occasionally from a jug?
 

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Discussion Starter #12
Why not bring it back to the mechanic you paid to investigate the problem?
He didn't charge me anything. He's a referral from a friend of mine and didn't think it fair to charge anything.

I rode around today and was able to replicate the problem. I tried to ride with the petcock OFF. When the bike runs out of gas I turn the petcock to ON and it still has the same problem. I can get full fuel if i play around a lot with the petcock I'm hoping the petcock is the answer. I put seafoam in but didn't make a difference.

He feels its a fuel issue and not an electric issue. He wants to change the petcock and the fuel filter. I suggested lets to the pump too while we're at it - all OEM, even though the guy i got the from did all those things about16 months ago. I'll check the battery myself.
 

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Discussion Starter #13
It's hard for the tech sometimes to replicate the intermittent problems, not defending him, just saying they often just hand it off to you the second things seem to be ok and it's on to the next. I second the thought of battery cables, doesn't hurt to clean the connections and rule that out. I would pull the main line from the tank and see how much fuel is flowing out into a cup in ON position and RES, then look at the quality of the fuel, check for water separation. Do you always fill up at the pump or occasionally from a jug?
Never fill up from a jug. I'm just going to change the fuel system on the bike - petcock,filter, pump. The mechanic NEVER saw an issue with the bike because it is intermittent. i picked it up from him and rode perfectly for 80 miles. Then it started acting up. I will definitely have him check the connections of the battery cables.
 

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Never fill up from a jug. I'm just going to change the fuel system on the bike - petcock,filter, pump. The mechanic NEVER saw an issue with the bike because it is intermittent. i picked it up from him and rode perfectly for 80 miles. Then it started acting up. I will definitely have him check the connections of the battery cables.
Yea the petcock seems like the culprit.. some kind of blockage or someone tried using a sealant or something got past the screen and is stuck in the valve itself. Hope you get it figured out!
 

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Yea the petcock seems like the culprit.. some kind of blockage or someone tried using a sealant or something got past the screen and is stuck in the valve itself. Hope you get it figured out!
I sure hope so. I'm friends with the guy who sold me the bike and he feels bad. he really can't even imagine what's wrong. I would just prefer to change everything and be done with it. I sure hope these 3 things fix the problem.
 

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Check the tank vent hose, be sure it's open, Could be it's getting a vacuum in the tank when you've used enough fuel, it quits as the pump can't override the vacuum. may be worse on colder days, sometimes the fuel sloshing in the tank creates vapor pressure that counter-acts the vacuum on hot days.

Also try jumpering the fuel cut-off relay under the right side cover. All you need is half a paperclip and some electrical tape. Relay is supposed to kill the pump if you crash and the motor stops. They fail and stop the pump. Could be you're gravity feeding until the fuel gets low. 3 wire connector under right side cover with black, black/blue and yellow/blue.wires. Unplug and jumper harness plug black (12v) to black/blue (power to pump motor.) ...

Edit: And they will run approx 1/2 to 3/4 of a mile with the petcock off.
 

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Apparently you got yourself a GOOD Mechanic to handle the situation...
All these suggestions are good too, I`d check each FREE thing, fer sure,
Dennis

Clogged or pinched tank vent also comes to mind @oldguy
 

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Check the kickstand safety switch as well. If the kickstand is a little loose and/or the switch is failing, it will cut the ignition.
 

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That is odd. Usually if the airbox is moded amd too much air gets in, it will bog down. If the fuel pump relay is bad, it may be gravity feeding and not enough fuel is pumping in so sudden throttle may cause it to starve.

Also, check the three yellow wires going from the Stator/rectifier as on the 02 shadow, the wireing harness is k own to melt from resistance and cause it to lose power. Lights will flicker and dim and gail once all three melt and corrode apart. This is under the seat and easy to find if you follow the rectifier wires to the harness clip. It will dry, crack and melt there.
 
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