So I'm riding to work this morning, it's roughly 45°F outside. I've already ridden to the gas station, gotten gas (filled ALL the way up), had my morning cigarette, then rode another 8-10 miles. I'm buzzing along the highway at about 75mph (indicated) when suddenly the bike (my 97/98) starts acting like it's running out of gas. I immediately start trying to get over to get off on the shoulder. By the time I enter the center lane (I was in the left - 3 lane highway), the problem mysteriously disappears. I'd say it lasted maybe 15 seconds.
What gives here? I mean, why would it just all of a sudden decide to start acting like that if it was fine before? There's nothing in my fuel tank that would've clogged up my carbs, the gas is fresh, I had just ridden it the day before, and the spark plugs have less than 500 miles on them.
I rode it the rest of the way to work (about another 5 miles) and it seemed fine - no more sputtering. Is this an indication of a problem to come or just a random gremlin? It just seems weird because it was fine for the first part of the ride...and then all of a sudden, out of nowhere, it just starts acting up. I was maintaining about 6k revs, give or take a few hundred, for over 10 minutes prior. So, it's not as if it came up whilst accelerating.
Yeah.. mine did this, but mine actually died. I looked at the carbs all day. maybe you lose oil pressure or something.. idk. still working on mine.
Happened once to me, too. The mysterious "fuel starvation" problem. It happened just once, and that's with a few thousand miles at over 75mph. The petcock on my bike is not vacuum operated. Someone here, (maybe gsJack?) has a theory about air currents causing high or low pressures in the float bowls via the vent. I tend to think that is more likely than flow restriction through the petcock.
Oh, so this isn't anything new. Well, that's good to hear. Because as soon as I started slowing down and letting off the throttle...it went right back to being fine. Such an obscure and weird problem! Damn Suzuki engineers and their voodoo-magic with air currents and whatnot!
Paulcet, I have the stock vacuum petcock on my bike. So, yay or neigh on that?
Quote from: J_Walker on February 01, 2012, 05:21:17 PM
Yeah.. mine did this, but mine actually died. I looked at the carbs all day. maybe you lose oil pressure or something.. idk. still working on mine.
Yeah I think you're experiencing a totally different problem, personally. I wish I could help you but I really don't know what to tell ya.
Quote from: Kijona on February 01, 2012, 05:36:16 PM
Quote from: J_Walker on February 01, 2012, 05:21:17 PM
Yeah.. mine did this, but mine actually died. I looked at the carbs all day. maybe you lose oil pressure or something.. idk. still working on mine.
Yeah I think you're experiencing a totally different problem, personally. I wish I could help you but I really don't know what to tell ya.
no one knows.. its up to me to figure it out. hopefully replacing the shims. and rebuilding my carb will fix what ever was wrong..
Probably random. There is a tiny air vent in the gas cap. Without air getting in, fuel can't flow out. Possible it momentarily was clogged from overfilling the tank? Maybe the splashing of the gas caused an air bubble to get into the tank pet chicken? (Yea, I know - chicken! )
Gas is gravity fed. Maybe overfilling and hitting a bump momentarily flooded the engine because the floats couldn't stop the flow of gas?
Quote from: adidasguy on February 01, 2012, 05:39:42 PM
Probably random. There is a tiny air vent in the gas cap. Without air getting in, fuel can't flow out. Possible it momentarily was clogged from overfilling the tank? Maybe the splashing of the gas caused an air bubble to get into the tank pet chicken? (Yea, I know - chicken! )
Gas is gravity fed. Maybe overfilling and hitting a bump momentarily flooded the engine because the floats couldn't stop the flow of gas?
Great points, Chicken Man. I'll keep those in mind and see how it performs tomorrow. ;)
Mine almost got out this morning - I hate when that happens. Then you have to go chasing it around and stuff it back in there before anyone sees you. "Why yes...there's a tiny pet chicken in my tank and it feeds my motor gasoline!"
Although mine is still new to me and today was only the 2nd commute to work on it, I had the same issue with mine today. 2001 with stock vacuum operated petcock, about 1 1/2 gallons of fuel in the tank, petcock in the "on" position. I took the main highway (Rte 95) to work today, going 70-80 mph for about 14 miles, went to slow down to about 50 for the exite ramp.....when I got back on the throttle and get up to speed it starts surging like it's starving for fuel.....so I switched the petcock to "reserve" and she immediatley started to run fine like nothing happened. After a bit, I switched the petcock back to the "on" position and went another 8 miles at 70+ mph....again when I slowed down to take the exit it started acting up when I got back on the throttle. I stopped at the next gas station thinking that I had not put as much fuel in the tank as originally thought. I topped it off with 3.4 gallons of fuel and proceeded on my way with the petcock in the "on" position. A "vacuum lock" does sound like it might be the idssue after reading all these posts. I guess taking the fuel cap off the bike and cleaning the vent manually should solve this issue.......My 2 cents.
craig: you ran out of gas.
The reserve amount is about a gallon to a gallon and a half. Someone may know the exact amount.
Basically: ON: I don't run
RESERVE: I do run.
CAUSE: low on gas. Fill her up.
TOPPED OFF TANK: all OK from that point on.
FYI: Reserve and ON take fuel in the same way from the tank. The ON tube is a little higher, the reserve tube or fuel outlet us low. Vacuum lock would affect both settings.
Quote from: adidasguy on February 01, 2012, 07:01:07 PM
craig: you ran out of gas.
The reserve amount is about a gallon to a gallon and a half. Someone may know the exact amount.
Basically: ON: I don't run
RESERVE: I do run.
CAUSE: low on gas. Fill her up.
TOPPED OFF TANK: all OK from that point on.
FYI: Reserve and ON take fuel in the same way from the tank. The ON tube is a little higher, the reserve tube or fuel outlet us low. Vacuum lock would affect both settings.
Really? the reserve amount is 1 1/2 gallons...........Good to know. Plus, now that I am filled up, I will take the highway home in a few hours and see if that same problem persists...
Quote from: Paulcet on February 01, 2012, 05:32:33 PM
Happened once to me, too. The mysterious "fuel starvation" problem. It happened just once, and that's with a few thousand miles at over 75mph. The petcock on my bike is not vacuum operated. Someone here, (maybe gsJack?) has a theory about air currents causing high or low pressures in the float bowls via the vent. I tend to think that is more likely than flow restriction through the petcock.
You're probably referring to this I posted a couple years ago:
A letter in the service section of the Jan issue of CW mag said:
...............I own a 2000 Suzuki GS500...............Most of the time it runs flawlessly, but it's had a quirk...................When I encounter exceptionally windy conditions, the engine often stumbles and sputters as if starving for fuel................The moment the gust lets up, the engine immediately settles back down and runs fine.........................The bike is absolutely stock........
To which CW gave a long winded answer about being too lean and rejetting, etc, etc...........
Follow up in latest June issue of CW:
In the ...Jan issue, TA described a problem with his GS500........I've had this same problem with two of my bikes........82 GS850GLZ........84 CB700SC. I resolved the problem on both bikes by rerouting the carb float bowl vent tubes to keep them out of the wind..............
Something to think about, I find it very difficult to believe this is just a head wind problem posted by the OP. I had my 97 GS500 up to 110 mph indicated with a Plexi 2 shield and my 250# butt on it.From this thread:
http://gstwins.com/gsboard/index.php?topic=52255.msg590528#msg590528
Quote from: J_Walker on February 01, 2012, 05:21:17 PM
Yeah.. mine did this, but mine actually died. I looked at the carbs all day. maybe you lose oil pressure or something.. idk. still working on mine.
It may be your petcock, this happened to me a while back. It would act as if its running outa fuel even though i just filled it up. This only happens in the ON position, when its on RESERVE, its fine. So i took it in to the shop and had it replaced, then after that it runs fine.
You haven't really owned a GS unless it has left you stranded somewhere. Mine acquired an electrical gremlin whilst on a ride in the country after i fitted dual headlights. I played with just about every wire in that humongous GS loom and every fuse I put in blew. I even tried to McGyver some tin foil I found on the side of the road to no avail. Lucky I have good friends who came out and got me.
i believe that the moter has a shortage of vacuem at these continue's high revs even though it has constant high velocity carbs ..I know that 6000 rpm is not high for these motors but they have a tiny vacum tank and diphram s on carbs and petrol tap take there toll..MY MOD FOR THIS WAS TO USE THE LEFT CARB TO SUPPLY VACUEM DIRECT TO THE PETROL TAP DIAPHRAM,AND ITS EASY TO USE THIS HOSE TO TUNE THE ENGINE INSTEAD OF TAKING THE LITTLR RUBBER CAP OFF TO DO A CARB TUNE UP..i also installed another vac tank for the left carb..
I have never had a fuel starvation problem from running at 6k rpm for extended periods of time.
If you do, you have a fuel flow issue. The cause of which can be one or more of some of the following...
- blocked or restricted air vent into the tank (open cap and ride and see if problem persists)
- fuel level below ON petcock in tank
- pinched/kinked fuel line (bike will run at slower speeds but fuel cannot flow fast enough at higher speed due to fuel line restriction)
- fuel filter (causes slight fuel flow restrictions)
There are others, but these are the easiest to check and fix. Go through these first.
Michael
Quote from: mister on February 02, 2012, 02:21:23 AM
I have never had a fuel starvation problem from running at 6k rpm for extended periods of time.
If you do, you have a fuel flow issue. The cause of which can be one or more of some of the following...
- blocked or restricted air vent into the tank (open cap and ride and see if problem persists)
- fuel level below ON petcock in tank
- pinched/kinked fuel line (bike will run at slower speeds but fuel cannot flow fast enough at higher speed due to fuel line restriction)
- fuel filter (causes slight fuel flow restrictions)
There are others, but these are the easiest to check and fix. Go through these first.
Michael
+1
If you are having a fuel starvation problem there is definitely something wrong somewhere.
-Jessie
Ah,yes. The mysterious GS 'fuel starvation' issue ...
Some of you have electrical problems but you're fixated on the fuel/carb side of the equation - electrical is as important if not more so, especially on older vehicles.
The spark test, in the shop, cool engine/electrics, cranking with a fully charged battery against no compression - isn't much of a test. Better than nothing but not by much.
Primary circuit , high tension circuit, all components there-of, can possibly mimic 'fuel starvation' in partial or total failure mode.
Quote from: craigs449 on February 01, 2012, 07:05:55 PM
Quote from: adidasguy on February 01, 2012, 07:01:07 PM
craig: you ran out of gas.
The reserve amount is about a gallon to a gallon and a half. Someone may know the exact amount.
Basically: ON: I don't run
RESERVE: I do run.
CAUSE: low on gas. Fill her up.
TOPPED OFF TANK: all OK from that point on.
FYI: Reserve and ON take fuel in the same way from the tank. The ON tube is a little higher, the reserve tube or fuel outlet us low. Vacuum lock would affect both settings.
Really? the reserve amount is 1 1/2 gallons...........Good to know. Plus, now that I am filled up, I will take the highway home in a few hours and see if that same problem persists...
So I rode it home last night on the highway for extended (8+ miles) duration at 70-80mph.....I had no issues at all whatsoever :cheers: Must have been me not knowing when this bike hits reserve....Good times :cheers:
I had the identical thing happen. Filled up, drove about 5-10 miles at 70 mph and the bike sputtered and died. Wouldn't start for about five minutes. Tried switching petcock settings. No luck. After five minutes, fired up and rode the remaining 40 miles home without a hitch. Talked to a mechanically inclined friend who wondered if something (slugg) was caught in the trap/filter where the gas exits the tank. It hasn't happened since and I haven't pulled the tank to see if I need to clean something out.
Quote from: mister on February 02, 2012, 02:21:23 AM
I have never had a fuel starvation problem from running at 6k rpm for extended periods of time.
If you do, you have a fuel flow issue. The cause of which can be one or more of some of the following...
- blocked or restricted air vent into the tank (open cap and ride and see if problem persists)
- fuel level below ON petcock in tank
- pinched/kinked fuel line (bike will run at slower speeds but fuel cannot flow fast enough at higher speed due to fuel line restriction)
- fuel filter (causes slight fuel flow restrictions)
There are others, but these are the easiest to check and fix. Go through these first.
Michael
I had just filled up. I had been riding at that speed for over 10 minutes with no problem. There is no fuel filter other than what's inside the tank but I had the tank off and cleaned it less than 500 miles ago. It was clean when I cleaned it...now it's even more clean.
My guess is it was caused by what Adidas was describing - because I rode it home this morning and it performed flawlessly. Who knows? :dunno_black: If it does it again I'll let you guys know.