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**lartross** · 10-12-2003, 10:32 PM

Possibly a vaccuum lock in your fuel system? Than would be your fuel tank not venting...

**AOD** · 10-13-2003, 02:10 AM

sounds like what happens when the bike runs out of gas in the ON position. it'll cough and not do much because its only getting a little fuel...

if it happens again...switch it to reserve, or prime as a last check, and see what happens.

**KEITH KRAUSE** · 10-13-2003, 02:34 AM

Such a loss of power and so suddenly, makes me think you lost 2 cylinders. You may have a coil going bad.
If it does it again, as soon as you stop and turn it off, quickly feel the headers for a difference in heat. A bad coil will make 1&4 or 2&3 cylinders run much less hot to the touch or even cold if no spark at all.
It's also possible you only lost 1 cylinder due to a poor connection at the coil/plug lead/cap. In this case, you should still feel one of the pipes running much cooler than the rest.
For it to happen so suddenly, I think it's electrical. Electrical connections commonly work when cold but fail when they get hot. I'm not familiar with your ignition but it may also be a failing sensor/pick up in your ignition.
Clean or replace the leads/caps and tighten all connections and then test.

**Anonymous** · 10-13-2003, 02:39 AM

Sounds like a brutal commute. Or at least it would be in a car...

Careful about feeling the exhaust. Them things is hot. You should also take a whiff of the cold cylinder(s) if you can find it. At least you'll know whether that one's not getting gas or not getting spark.

Other possibilities include any variety of fuel starvation problems. Perhaps a fuel line is intermittently plugged. Check for debris at the fuel filter between the tank and carbs. If you don't have one, that's bad. Get one. It might take some tracing of the fuel path to find any blockage

Which model and year is your bike?

--

Funny story:

When my GS was new to me I had a similar sounding problem. It sputtered for a mile, then totally lost power and I couldn't start it again. I came back with a trailer and hauled it home, but I eventually found the problem. It was nothing a few gallons of gas wouldn't fix...

In my defense, I have no gas gauge and I was rightfully expecting to go much farther on the tank. A little spark plug gap problem was causing poor gas mileage. I really should have tried the reserve setting before I hauled it home, though. Live and learn.

--

Best of luck, Tyler.

-Michael

**KEITH KRAUSE** · 10-13-2003, 02:45 AM

To add to what I suggested earlier, if the bike does it again, keep riding for at least a couple miles before checking. If you pull over immediately, the pipes will still all be hot. Giving the no sparking cylinder(s) time to cool a little will make it easier to tell the difference and troubleshoot.

**Anonymous** · 10-13-2003, 01:45 PM

Keith - I don't think any of the cylinders weren't firing. When it died the first time, it was still running smooth as it slowed down. If I'd lost one or two cylinders, I think I would have felt quite a noticable difference in how smooth it was running. On the first time, it started dying such that I couldn't continue (just kept slowing down until it hit zero), sort of suggesting that it was some sort of fuel starvation thing.

The gas tank was well over half full, so it wasn't due to an empty tank. I don't have any fuel filter on the bike, other than the screen just before the petcock. Is that enough, or should I look into getting something more serious? If so, any suggestions?

To me, it seems like the fuel isn't getting to the carbs due to a blockage or something. I plan on taking out the petcock and looking at it/cleaning it, but am a little hesitant to do so at this point until I have another O-ring to replace the current one (just in case it gets damaged or falls apart when I take it out).

Lartross - from what I can tell, the fuel tank is venting just fine. I know in the past, there has been no trouble for air to get in (and fuel out #-o ).

--Tyler

**QuaiChangKane** · 10-13-2003, 08:34 PM

This happened to me once, going over a windy pass on the freeway. I got the bike to the shoulder, fiddled with the petcock, and finally got it started after about 5 minutes.

When I got it home, I took the petcock apart, but there was no noticeable blockage, and nothing functionally wrong with the petcock or fuel/vacuum lines. The only thing I did was grease the switch o-ring.

That was 3,000 miles ago, with no repeat. The only thing I can attribute it to was cheap gas. I almost always run major brand premium now, with no problems.

Not much help, but thought I'd relate....

-Q!

**argonsagas** · 10-13-2003, 09:37 PM

What you are describing sounds like a weak or failed condensor on a standard ignition.

Do you have standard ignition on yours?

**moto_dan** · 10-14-2003, 09:59 AM

I had a similiar problem back in June on our 2nd Hill county ride on my 750. After discussing several possibilites with several other GSers we removed the fuel tank, dissembled the petcock and found a small piece of debri partially clogging the outlet. Removed the debri and my bike has run fine since.

**Anonymous** · 10-14-2003, 10:46 PM

Ok, I had the opportunity to test the bike again today as I drove it back down to school with me. The bike went out two different times. In both cases, it started losing power.

First time, I went just a little way, then drifted to the side of the road and killed it. Let it sit for a little bit, then tried it again and got it going.

The second time, I was able to ride it out for about a mile, but it got continuously slower. I started at about 60 mph, then within a mile couldn't hold above 40 even with full throttle. I drifted to the side (clutch in), and it immediately stalled. Took some time and working with the starter to get it going again.

One thing I noticed was that these times also seemed to correspond to some smoke being given off by the left exhaust pipe (oil slipping into cylinders and burning??). I don't know if this could be related to the problem, or if it's an entirely different problem. I plan on working on the petcock soon, as so far I think it's related to some fuel clog. I'm a little worried about the smoke coming out of the pipe though.

I also noticed again that as the bike lost power, the ride didn't get any rougher. Also, I felt the heads of the exhaust pipes the second time, and they were all the same temperature. These lead me to believe that all the cylinders are firing, and that isn't the problem. Thanks for the help!!

--Tyler

**Anonymous** · 10-14-2003, 10:56 PM

Was the smoke black/sooty or bluish? Black means not enough air for the fuel. Blue means oil burning.

I would agree that fuel path inspection should be the next step.

Michael

**KEITH KRAUSE** · 10-15-2003, 02:58 AM

You can loose 1 or 2 cylinders and still run "smooth" as you lose speed and pull over. It may very well be fuel related, but I don't understand why the bike would run OK and then suddenly starve for fuel, again and again.
A clogged fuel passage usually stays clogged,or passes, instead of what you're describing.
Feeling the pipes will only work if you can ride the bike a couple of miles after the problem starts. If you pull over too soon, the pipes will still all be hot. I know you may not be able to continue running a couple miles.
You can also check the plugs for spark at this point.
I still think it's electrical.

**Anonymous** · 10-15-2003, 03:14 AM

Michael - smoke was a bluish, which I guess means oil burning. Would this be related to my other problems? or a totally separate problem?

Keith - I don't understand why it would happen repeatedly either, or why letting it sit a little seems to solve the problem for a short while. Where is the best place to start for checking the electrical? With the spark plugs?

Also, I said I thought I'd notice it running less smooth because in the recent past, I ran with it for a while with only three cylinders firing. Had to replace a spark plug cap to fix it, but there was a noticable difference having the fourth cylinder instead of just three. Also, I'd think even with two cylinders, I'd be able to keep it going, although not fast or well. However, the bike basically forces me to stop, and stalled as I pulled off the road with the clutch in.

--Tyler

**Anonymous** · 10-15-2003, 05:26 AM

I can't think of a plausable connection between the blue smoke and the loss of power other than engine mechanical stuff, and I'm the wrong guy to talk about that (until I get myself edjumukated).

Can you think of any way that the loss of power is following a cause pattern? Is it at a certain time or distance in the ride? Is there any relation to the level of fuel in the tank, or switching anything in your fuel supply (choke, reserve, throttle)? Is it only on inclines, declines or after blinking twice?

Just for brainstorming, is there any impediment to your air flow? Is your airbox clear and have you cleaned the air filter recently? Who knows, maybe your seat is suffocating it somehow, when you put your weight on it just so.

If you can safely manage the bike, I might suggest that you not hit the kill switch unless something terrible is going to happen. Maybe there's a clue hiding in the low rev environment.

You said in the first post that it had some trouble starting after your 30 min wait. What did the bike do and not do during the starting trouble?

If there is a chance you bring a laptop with you on this commute, perhaps you could audio record the situation once you come to the first stop. My dad's a wizard at hearing what's going on in an engine.

Perhaps it's gremlins... or maybe gnomes...

Michael

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