EN500 Stalls on Highways

[kraaazymike]

Hey guys, this is my first post here. I'm hoping you guys can point me in the right direction and give me some ideas.

I bought my Vulcan EN500 new two years ago at a dealership and now has ~6k on the odometer. The other month while riding at around 75mph on the freeway, the engine felt like it lost all power but was still running. Slowly but surely the bike slows down and the engine quits. I pull over to the side of the road. The oil and battery light are on and nothing else looked out of the ordinary so I tried starting it again. It took a few tries to start but it started right up and ran as smooth as nothing ever happened.

I was able to repeat this 4 or 5 times at highway speed and never at any speed lower than 75mph. So after checking the obvious and battery connection, I got to installing a tach to get a better feel for what was going on. I found that if I cruise at ~75mph(6k rpm) the engine will spontaneously drop to ~4.5k rpm. If I loosen the throttle, the RPM's drop by 500 or so in increments until the engine completely dies. Increasing throttle has no effect.

I took it to the dealership as it's still under warranty on June 8th. It's July 4th now and yesterday they told me they can duplicate the problem but can't figure out why it's happening. They checked fuel lines and everything electrical but they're close to giving up. So now they want to charge me the $90 diagnosing fee for my bike that's under warranty for the 5 man hours they spent to tell me they can't fix it.

Anyone got any ideas? I'd appreciate any and all help!

[philipd]

Hi Mike,

Welcome to the forum.

I had the same problem you are describing. Mine was caused by a loose battery connection on the negative side. There are actually two screws on the negative side of the battery. One screw comes in from the top and attaches the cable to a metal block. The other screw goes in the side and attaches the block to the battery. The one on the side is VERY hard to see and I only found it because I removed the battery. I tightened it up and no more problem.

As far as the dealer goes: I would fight them tooth and nail over this. It might not do any good and you have to cough up the $90 anyway but I would sure raise a fuss.

Hope this helps.

[kraaazymike]

Originally Posted by philipd

Hi Mike,

Welcome to the forum.

I had the same problem you are describing. Mine was caused by a loose battery connection on the negative side. There are actually two screws on the negative side of the battery. One screw comes in from the top and attaches the cable to a metal block. The other screw goes in the side and attaches the block to the battery. The one on the side is VERY hard to see and I only found it because I removed the battery. I tightened it up and no more problem.

As far as the dealer goes: I would fight them tooth and nail over this. It might not do any good and you have to cough up the $90 anyway but I would sure raise a fuss.

Hope this helps.

When I get the bike back, that sounds like something I'll definitely look into! I checked the battery but didn't think of taking it out. Thanks!

[Lawn Masters]

I suspect tank vent. next time it happens, open the filler cap and see if you hear a sucking sound. if you do, its the vent being clogged/obstructed somehow and needing cleaning.

[BlueNinja14]

Originally Posted by Lawn Masters

I suspect tank vent. next time it happens, open the filler cap and see if you hear a sucking sound. if you do, its the vent being clogged/obstructed somehow and needing cleaning.

My thought too.

[kraaazymike]

Originally Posted by Lawn Masters

I suspect tank vent. next time it happens, open the filler cap and see if you hear a sucking sound. if you do, its the vent being clogged/obstructed somehow and needing cleaning.

Freeways are loud, especially with a full face helmet. But shoot I'll give anything a shot!

Shop said they checked all vacuum lines. But who knows? I'll definitely try it if I ever get the bike back! Thanks!

[Lawn Masters]

the tank vent is in the cap, there are no lines to it. just so you know.

[kraaazymike]

Good to know. Probably obvious but I'm a complete beginner to bike wrenching. Fluids, chain and tire maintenance are about as much as I've figured out on these things.

[Lawn Masters]

you'll get good at all of it in time. the EN 500 is the same engine as the EX500, check the ex-500.com wiki for education on how to maintain your engine. very informative.

[BlueNinja14]

" the tank vent is in the cap, there are no lines to it. just so you know."


There are if its a California bike. There is a vapor purge and it has a carbon canister and fuel return pump in the event fuel gets into the system. If the check valves in the fuel cap get plugged or stuck then a vacuum is created in the tank and will cause what is happening to his bike.

[Lawn Masters]

ok true, the cali models are a bit different, so yeah you're totally right.

[BlueNinja14]

I had a 2004 ZRX1200 that had a few mods, one was to remove the smog stuff. I did experience the same problem. I gutted the fuel cap to allow free flow for expansion and fuel draw to the carburetors. My wife's EX500 has the same smog junk but left alone, for now.

[kraaazymike]

Originally Posted by BlueNinja14

" the tank vent is in the cap, there are no lines to it. just so you know."


There are if its a California bike. There is a vapor purge and it has a carbon canister and fuel return pump in the event fuel gets into the system. If the check valves in the fuel cap get plugged or stuck then a vacuum is created in the tank and will cause what is happening to his bike.

Is there any specific way to check to see if these things are plugged? I know I'd probably just try blowing on them after disconnecting and seeing if air comes out the other end.

[BlueNinja14]

Originally Posted by kraaazymike

Is there any specific way to check to see if these things are plugged? I know I'd probably just try blowing on them after disconnecting and seeing if air comes out the other end.

If you have a vacuum pump you could hook it to the blue labeled line (plug the red one) that goes to the bottom of the fuel tank and see how much vacuum it take before it draws air in. Should be very low vacuum pressure. Here is a link to the ZRX1200 cap I gutted California Gas cap - ZRXOA Message Board

[kraaazymike]

Originally Posted by BlueNinja14

If you have a vacuum pump you could hook it to the blue labeled line (plug the red one) that goes to the bottom of the fuel tank and see how much vacuum it take before it draws air in. Should be very low vacuum pressure. Here is a link to the ZRX1200 cap I gutted California Gas cap - ZRXOA Message Board

Most informative! Thanks!

[kopcicle]

Now that the resident pros hit on the easy stuff (and good stuff). I'll just provide a bit of alternate thinking . When were the valves last adjusted ?

~kop

[kraaazymike]

Originally Posted by kopcicle

Now that the resident pros hit on the easy stuff (and good stuff). I'll just provide a bit of alternate thinking . When were the valves last adjusted ?

~kop

At 600 miles. Owners manual tells me the next one's due at 6000 miles. I'm just under 6k on the odometer.

[kopcicle]

well then ...

[Lawn Masters]

thats POSSIBLE, but not likely to be the issue. do you have a fuel filter? I'm also thinking possibly a plugged filter may be at fault. its happened to me before, so its worth considering.

[philipd]

So Mike, how much longer is the shop going to have your bike? Heard anything from them yet?