Low idle RPM, sputtering -- "Fixed" after refilling gas?

TekNinja81

TekNinja81

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Hey guys, I may already have the answer to this one but just wanted to get a 2nd opinion or two.

Bike has been running fine up until yesterday. Was on the highway and I noticed that regardless of gear, around 5-6k RPM (power-band area) the bike would sputter & lurch, as if I were chopping the throttle sharply. At higher RPMs, the bike would smooth out but I had some loss of power/torque.

Got off the highway and as soon as I slowed to road speeds, again around the 5-6k RPM range the bike would sputter & lurch, more noticeably. Pulled over and the bike stalled, or would idle very low & inconsistently (900-1000rpm vs usual 1500.)

Here's my theory: I usually fill up at Esso or Shell, 87-octane, only at stations near my home; my last fill-up was at the Esso by L&L, where I very rarely refuel. I'd burned through 2/3 of my tank last night so I filled up using 91-octane at a Shell (my thought was maybe the higher octane would "clean" the gas a bit?), and the bike immediately ran more smoothly for the remainder of the night. This morning however, I noticed the low-idle issue again (but no sputtering yet.)

I know it's somewhat common for the gas filter on V-Stroms to get clogged up/dirty, so this is one possibility I suspect, however I'm thinking due to the Shell gas working for me, maybe I just got a bad tank of gas at the Esso. Is there anything else I should be looking into at this point, assuming the problem does continue once I get rid of this tank of gas?

Appreciate any constructive input, thanks guys!
 
If it's running fine now, it's very likely it was bad gas. Keep an eye on it... if it happens again then you can start further investigation. Also, it never hurts to run some Seafoam through to help clean it up a bit.
 
I'm actually about to do exactly that. I've never used the stuff before but I've read on several forums that it has been helpful in such cases. Hopefully it is for me -- the bike has over 50,000km on it so I'm sure there's some crap to be cleaned out.


Update: Put in a bit under 1/3 of a can into a full tank, let the bike sit for about 30-45 minutes then let it run for about 5-10 minutes prior to going for a ride. Bike ran beautifully, perhaps even a little smoother than it has for a while. Now if only the same could be said about my back, lol. Somehow managed to pull/irritate something in my back putting on my helmet, quickly put an end to my late-night riding for the night. :(
 
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Ugh. So, bike was running beautifully.

Now I'm stuck at KC and the bike won't maintain idle RPM, keeps stalling out. Ran great til I got here, literally died as I was parking. I AM down to about 1/4 tank again, maybe whatever gas is in there is crap... but honestly not sure what to think now.

Guess I'll have to get the gas filter checked, maybe valves?
 
Check your vent hoses for your fuel tank, make sure they aren't plugged or blocked and that your cap is venting properly as well. You could be getting fuel starvation due to vapor lock in the tank. When the tank is full you would not notice it, as the tank empties more vacuum is built up if the tank is not venting properly. Just a thought, I had something similar on one of my track bikes. Good luck.
 
Ould said:
Check your vent hoses for your fuel tank, make sure they aren't plugged or blocked and that your cap is venting properly as well. You could be getting fuel starvation due to vapor lock in the tank. When the tank is full you would not notice it, as the tank empties more vacuum is built up if the tank is not venting properly. Just a thought, I had something similar on one of my track bikes. Good luck.
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I had thought of the vacuum issue, opening the tank doesn't seem to help. Issue went away again as soon as I filled the tank, so it definitely seems like either crap in the tank/filter.

Something I noticed this time that I never did before (never thought to check actually), was that there was a clearly laboured/weak sound from the Fuel Injector when I turned the key, versus what it would normally sound like. When I shook the gas around a bit and tried again (after a few tries already before that) it sounded normal again, started up fine but shortly after died again. So definitely seems to be a clog of some sort, right?

I dumped about 1/2 can of Seafoam into the tank last night with this full tank again, to see if that helps, but at this point I strongly doubt it will and that I'll have the same issue once I run low again.
 
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TekNinja81 said:
I had thought of the vacuum issue, opening the tank doesn't seem to help. Issue went away again as soon as I filled the tank, so it definitely seems like either crap in the tank/filter.

Something I noticed this time that I never did before (never thought to check actually), was that there was a clearly laboured/weak sound from the Fuel Injector when I turned the key, versus what it would normally sound like. When I shook the gas around a bit and tried again (after a few tries already before that) it sounded normal again, started up fine but shortly after died again. So definitely seems to be a clog of some sort, right?

I dumped about 1/2 can of Seafoam into the tank last night with this full tank again, to see if that helps, but at this point I strongly doubt it will and that I'll have the same issue once I run low again.
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If it's clog or crap in the filter, the level in the tank wouldn't matter, would it? If it's related to something in the fuel (crud or water), it would make more sense that it happens when it gets low.

I had a problem for a while that I thought was related to venting. It wasn't bad when I was cruising at a constant speed, but once I tried to accelerate (passing speed on the highway) it starve, and take a bit of time to recover.
It turned out the bike had an aftermarket fuel filter that was way too big. It never occurred to me, but each time I had been taking the tank off to check vent hoses, fuel lines, test the pump, etc I was creating the problem all over again. The fuel filter was sitting with air in it. A lot of air in it. Since the pump is only a transfer pump, it couldn't keep up when there was more demand.
 
Two50noob said:
does the v-storm have a inline fuel filter?
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No.

This issue sounds like water in the fuel tank, or clogged pick-up screen in the tank. Seeing as it pretty consistantly happens at the same fuel level, try completely draining the tank and starting with fresh fuel.
 
Iggy76 said:
No.

This issue sounds like water in the fuel tank, or clogged pick-up screen in the tank. Seeing as it pretty consistantly happens at the same fuel level, try completely draining the tank and starting with fresh fuel.
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This. Water sits at the bottom of the tank and as you're burning through gas towards the end you get to a point where its more water less fuel...
 
Well here we go again.

Took the bike to my local shop last week to have the tank drained, and the fuel pump/filter examined. They did so, found only a tiny bit of dirt in the screen/teabag-looking filter thing, which was removed and sprayed clean. They looked inside the tank and said it looked clean, and he suspected it may not be bad gas/filter, but perhaps the fuel pump itself not working well and not getting enough pressure. (This was just a guess though as he didn't have anything to test pressure etc.)

Left from there, bike ran quite nicely for the next few days, but once again on my way home today I had the same issues. Around 5K rpm, sputtering/lurching on the highway, and idling randomly from 900-1100rpm (I'm set to 1400-1500.) I noticed RPMs would fluctuate while the sputtering happened, but I'm assuming that happened before too, just didn't notice.

BTW, this time I had at least 3/4 tank of gas left.

Uggggggggh, what do I do next?
 
It could be a bunch of things, what's the bike like just off idle to the 5k mark? a fluttery idle sounds like a fuel delivery issue or charging issue(at idle your plugs aren't delivering a consistent spark). Overall sounds like the bike performance as a whole has dropped off, if so then other than fuel delivery it might be electrical in nature. What year is the bike?
 
Like the mechanic said and by process of elimination I would keep the fuel pump in mind as a possible culprit. However, that one is pretty hard to pin down as it is only sporadically happening and without a fuel pressure gauge on the system all the time, you can't tell if it's providing enough pressure. Perhaps as a last resort if it isn't too expensive, just replace the unit.

Start investigating the ignition system also. I can't be sure but it sounds like this generally happens when the bike is warmed up and/or hot. If you have separate coils, it's not unheard of to have a crack in one of them... works fine when it's cold but as soon as it warms up it will start acting up. Also carefully trace and inspect all your ignition wires. Inspect and check your spark plug caps, especially on the inside to make sure there's no corrosion or carbon which would indicate a bad connection that's been arcing. Inspect your engine while it's running outside at night when it's dark, look for any arcing in the ignition wires.
 
The bike's a 2005 model, got about 54k on it now if I haven't already mentioned.

Discovered something which neither myself nor the mechanic were aware of: The filter we cleaned, was not the main fuel pump filter -- but rather the low-pressure "pre-filter." The V-Strom's fuel pump has another, more-or-less integrated high-pressure filter which is more likely the culprit -- it's known for getting gunked up real bad over time -- and is not serviceable. Has to be replaced, and the OEM cost is ~$322; the whole pump is $812, either of which is ridiculous.

The fuel pump on newer models of the bike (they changed it from 2007+) cost around $550 for the whole thing. Going to check and find out if the newer pump is compatible, which I somehow doubt, but otherwise it looks like I may have a relatively pricey repair/replacement job on my hands assuming the HP filter is the problem.

What I'm worried about is if I get that replaced and I still have the problem. Trying to do this on a budget, but at the same time I need it fixed. At the same time I'm putting the bike in to have spark plugs replaced and valves checked/adjusted, as those are also due by now, and I'm trying to think of anything else that should be looked at in the meantime... I will also have a look at the electrical as suggested above.
 
I ride a Vstar and this season is brutal for water in my tank. Warm days, evening ride that heats up the tank and then temps drop over night. Filled up to brim last night, as the temps dropped pretty low again.

Will keep an eye in the thread, but sounds similar to my bike's sputtering issue. Hope it's just water. Mine has an inline fuel filter that may, replaced it an the problem got better, as long as I fill up just before parking over night.
 
I'll put my money on the fuel filter
 
never ever fill your tank at a gas station, where the tanker truck is filling the ground tank. it mixes the crap off the bottom and you pump into your tank, i've had this happen to me, i got a 1/4 tank of water, spread the word!
 
To follow up on my own post. I had the sputtering problem again, but this time I knew it wasn't water. A buddy suggested an electrical issue before. I wiggled the plug leads and the power came back.

What I am thinking is the bike gets hot, expands and leads loosen. Vibrations cause the loose lead to disconnect and thus loss of power... I am no mechanic and new to bikes. Will replace the plugs, tighten up and keep you posted.



Maxdar said:
I ride a Vstar and this season is brutal for water in my tank. Warm days, evening ride that heats up the tank and then temps drop over night. Filled up to brim last night, as the temps dropped pretty low again.

Will keep an eye in the thread, but sounds similar to my bike's sputtering issue. Hope it's just water. Mine has an inline fuel filter that may, replaced it an the problem got better, as long as I fill up just before parking over night.
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Glad you figured it out. Electrical issues are not fun
 
Before dumping a bunch of money and time into parts, take some time and inspect the basics....how old are the plugs in your v-storm?

If it is fuel delivery issue - it should do it at that same rpm very reguarly. Does it do that?
 
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