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I am reaching the end of my rope trying to figure out what is wrong with my 1996 Vulcan 1500 (VN1500). It started 2 weeks ago. I was riding to work and right before I got there I decided to fill up at a Shell station since I was on reserve. Filled up with unleaded 91 octane, drove 1 block to work and parked it. After work, I came out and tried to start it but it began to backfire, act like it was out of gas and die at idle. I manage to limp home keeping it revved high and riding through it's lurching and sputtering.

Then the following weekend I started working on it. I first thought the fuel was the culprit so I drained the tank and got gas from a different station. Didn't make any difference. I then tried replacing the fuel and air filters and the spark plugs which were carbon fouled, (covered with black dry powder). The engine ran a little smoother but still back fired when I revved, and idled . I tried riding it like this around the block and it would run fine then act like I was running out of gas and start to die. Then it would roar back to life and start the same cycle over again.

Last night after letting sit for a few days, I decided to burn the gas out of the lines by switching the petcock/fuel valve to "OFF". That way I could work on the rest of the fuel system, (fuel filter, carb, etc.) this weekend.

I did what I normally would with a cold start and pulled out the choke, opened the throttle and started the engine. After a few seconds, I switched the petcock to "OFF" and pushed in the choke. It seemed like it was idling ok so I let it set until the gas runs out. Not only did it keep running for over 15 minutes, but it idled fine too. I shut it down and now I am totally baffled. Does any one have any ideas what I should try to do next or what components to look at?

One other thing to keep in mind, I bought this bike used this spring and since it seemed to be running fine I've only changed the oil and oil filter, replace the front tire and brakes but have done nothing else to it. Also I don't know if any routine maintenance was been done in the past.
 

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Try posting in the Mechanics Forum. I posted a problem last night and got a reply right away.
 

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does it run well after you open the tank? the way you describe the engine wanting to die then coming back and cycling like that could be the vent. i'd check the gas cap first. i have experienced that before. not a mechanic by any means though. just an idea to check. hope you get it figured. post it when you do.
 

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Had a Yamaha that did the same thing. Negative connection was loose, but not on the battery. It was loose where it bolted to the motor. Tightened up and it ran fine untill the battery died about a month later.
 

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Discussion Starter #6
grunt said:
Try posting in the Mechanics Forum. I posted a problem last night and got a reply right away.
Good idea. It didn't even occur to me to post it there, (still new to the forum). :roll:

shooter said:
Check the battery and connections.
Will do. I'll hook up my volt meter to it this weekend and check the output. The starter seems to turn over strongly, but you never know. I was thinking of pulling out the plugs to see if they are firing also.

mastercaster said:
does it run well after you open the tank? the way you describe the engine wanting to die then coming back and cycling like that could be the vent. I'd check the gas cap first. I have experienced that before. not a mechanic by any means though. just an idea to check. hope you get it figured. post it when you do.
Hmm... Now that I think about it I may have had my cap off when I did the last start, (with the valve in the "OFF" position). I don't remember if I did the other times. I'll give that a try and let you know.


One last thing that I didn't directly ask in my first post that I'm still wondering about, is the bike suppose to keep running with the fuel valve in the "OFF" position?

Thanks for everyone's help!
 

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Discussion Starter #7
Spookyb4 said:
Had a Yamaha that did the same thing. Negative connection was loose, but not on the battery. It was loose where it bolted to the motor. Tightened up and it ran fine untill the battery died about a month later.
Shooter had said the same thing but I'm glad you posted because I wouldn't have thought to check the connections away from the battery. Thanks!
 

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I know different bikes have different features, But my VN800 petcock doesn't have off....Up is res, down is on, to the side is pri...doesn't turn to any other position. I have heard about problems with the gas cap vent causing it to die or sputter.

Hope you find the problem soon. Repost and let us know what you find.
 
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