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As a new Vulcan 750 owner (1993 model) I have found that the bike dies when the fuel is getting low - even if I switch it to reserve. The engine starts to sputter like it is needing fuel, I turn the petcock to reserve, but it dies anyhow. I shake the bike to hear if there is still fuel - there always is - and then open the gas cap - after a few minutes of setting, it cranks up an runs okay again for awhile an then it can happen again. After I fill the tank again, it runs fine no problems until I get low on fuel again. Any ideas? Bad petcock? Vapor lock? I have noticed their seem to be pressure building up in fuel tank - I'm thinking the venting may not be working. Would appreciate any tips or sugggestions for fixes.

Thanks
WGN
 

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The same thing happens to me on my '86. It will be pretty low on fuel, but still have a bit in when it starts to die. My solution; fill up more frequently.
 

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Had similar problem. Cleaned tank and notice an "extra" petcok filter was floating around in the tank....great. One was on the petcock...one must of been left in at the factory?? I guess when the fuel was low but not empty this piece of plastic got caught in the reserve hole. If you seen the petcock there is no screen or filter on the reserve drain to stop any dirt or object. Not hard to remove tank and clean.
 

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I once had the identical problem. There was junk in the bottom of the tank. When the volume of fuel decreases, the floaties are more likely to restrict the fuel flow. I removed the tank, drained it, turned it upside down and blew it out with high pressure air.
 

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Not to argue with you, but I recently removed my petcock for a rebuild (due to similar issues at random tank levels). Filters were on the end of both the tall "ON" position tube and another mounted to the shorter "Reserve" port. I don't think you had an "extra" filter, I think it was detached. The Ron Ayers online fiche doesn't help the debate because it shows a single solid filter over both ports.
http://www.ronayers.com/fiche/400_0286/fuel_tank/fuel_tank.cfm?man=ka&groupid=10710&parent=10700

I think that there could be a vacuum issue (petcock opens when vacuum tube from carb opens the diaphragm) which is why I rebuilt mine with a new diaphragm and "sealed" the vacuum tube connection with a little bit of grease when I reinstalled it. Because the issue was always random, I can't make a guaranteed statement that I've fixed the problem, but so far (4000 miles to the desert southwest and back) I've done ok. There was a single incident with a little bit of sputtering when I transitioned from ON to Reserve, but I believe it was an isolated issue with either vapor lock or fuel starvation during the transition.

Best of luck to WGN on the problem.


joebro said:
Had similar problem. Cleaned tank and notice an "extra" petcok filter was floating around in the tank....great. One was on the petcock...one must of been left in at the factory?? I guess when the fuel was low but not empty this piece of plastic got caught in the reserve hole. If you seen the petcock there is no screen or filter on the reserve drain to stop any dirt or object. Not hard to remove tank and clean.
 

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I had this problem in my '92 VN750. What has fixed it is removing a plastic check valve in the gas cap. It's purpose seems to be to allow the tank to take in air but not allow a siphon action to occur as fuel expands on a full tank. I plan on replacing this valve with a new part in the future but removing it has fixed the low fuel starving and limited use reserve capacity.
Take the 2 screws out of the fuel cap (watch not to lose any of the 5 or 6 springs in the fuel cap) and you will see the plastic valve body. Remove it (also be sure to check and see if any of the tubes or fuel tank vents are blocked) reassemble the gas cap and see if it helps the problem. My mileage jumped up 2-3 MPG and I went 135 miles before reserve and 15 miles on reserve without a hik-up
JN
 

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seek and ye shall find....dam I love this site already....I just had that happen to me today when I went to gas station after getting fired back up it only took a hair over 2 gallons....I knew I had more in the tank...switched to reserve and still had to wait


TrashLord
Connecticut
93 VN750
 
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