Fuel Concerns and Questions

[Call Me Ahab]

Hey everybody,

I've been riding my gs850gz pretty consistently for the past three months (barring a 2 week period when it rained nonstop.) I've been fueling up with different grades of fuel, just testing response time and economy - and I think I have uncovered a mistake I've made. When I sync'ed carbs and reset my air mixture I was running 93 octane w/ 4 fl.oz of Seafoam per full tank of gas. Since this time, I've not been able to achieve the same power, acceleration, or response time. I didn't think it would make any difference, and perhaps it didn't - but is there any merit to the theory that -

At the time I set the fuel mixture, the fuel I am using in addition to any additives must remain consistent to retain the same response, idle, power, etc?


My next question is regarding the most peculiar buildup I've been finding in my bowls... After a month or two of consistent riding, the throttle response at the top end (or more often, idle and up to 1/4 turn) completely drops out. I pull apart my carbs and I find a strange pale-brown fibrous-looking material. It looks very similar to paper filter element if one dissolved and reformed... Now, the part I cannot figure out: I don't use paper filters. My air filter is a different color, and appears to be in perfect condition. No gaskets are this color, or material. I find small traces of the stuff in my fuel filter (nylon mesh in glass bowl) and a large quantity in the bowls themselves. It gathers in the bottom of the bowls - almost like it's something from the fuel undergoing phase separation and crystallizing... But what in the world would separate from fuel and crystallize?? The bike doesn't sit for more than 48hrs before I'm back on the road - always medium distance trips, 50 - 150 miles every day.

And lastly... I replaced my oil breather hose with a clear plastic one as a temporary replacement (working with what I had one hand until I could get some heavier line) and when I stopped after a long ride yesterday, I noticed beads of water inside the hose, in addition to the foam I would expect from an oil breather line. What would cause this water to exist in my lines? Is this just condensation from air finding its way in through the airbox?

Thanks for any and all input! You guys have a great week!

 

[JTGS850GL]

Answer to #1: The type of fuel you use should have no bearing on the sync of the carbs. Could it effect the idle mixture screw settings? Possibly, but will not effect much above idle and idle to pilot response.

Answer to #2: Could be rust formation in the tank collecting in the float bowls. I'd ditch the inline fuel filter as well.

Answer to #3: Stop being paranoid. Normal for some condensation to steam up and collect in that tube.

 

[Call Me Ahab]

Answer to #1: The type of fuel you use should have no bearing on the sync of the carbs. Could it effect the idle mixture screw settings? Possibly, but will not effect much above idle and idle to pilot response.

Answer to #2: Could be rust formation in the tank collecting in the float bowls. I'd ditch the inline fuel filter as well.

Answer to #3: Stop being paranoid. Normal for some condensation to steam up and collect in that tube.

1) Interesting... I'll try resetting everything with 87 octane and no additives, I wonder if the fuel / additive made any difference or if its just the accumulation of.. whatever that stuff is.

2) I don't think it's rust - it's possible though! The reason I say this: I acid-washed and then POR15 fuel coated the tank about 2 years ago; it's never remained empty for more than a couple days, so I don't think it's had a chance to rust... and it doesn't have the consistency of rust - the GS1000 definitely collects a bit of rust... If my cellphone hadn't fallen out of my pocket on I35 two days ago I'd post some pics of this stuff, I'm really curious as to what it is. I've thought about sending it off to a lab if I can't identify it Best description I can give is... well, imagine a paper-filter element just completely obliterated and then the fibers settled into a clump... It looks just like that, only very tiny, very fine... Whatever it is, wherever it's coming from, it seems to pass through my fuel filter... Also, why dump the filter? I know the tanks have that little "sock" inside, attached to the petcock - but I don't think it's sufficient these days.. Prior to the filter, I was accumulating a lot of debris in the carbs. I haven't pulled the petcock since I cleaned the tank, but I'm guessing that nylon mesh came loose or tore somehow. I really wish I could figure out what this stuff is - or where on earth it's coming from! This is my fifth time this year pulling my carbs to wash this garbage out... My next step is to run this tank of fuel to empty and then pull the petcock and completely rinse my tank... Maybe it's SOMETHING in there, but again, I have no idea what...

3) Ah... that's good to know, appreciate it - I'll leave that alone then!


ps., Is anyone aware of a reaction or additive that would cause any sort of crystallization in fuel? All I have used is Seafoam, and I use it regularly in all my vehicles... I can't imagine this being the problem, but I know there are plenty of folks out there with more experience and greater wisdom than I.


Thanks JTGS850

 

[2BRacing]

Does the fuel you use contain ethanol (even in low volume like 10%)? I read somewhere that ethanol can cause all sorts of problems.

 

[cowboyup3371]

Most fuel filters you can get, unless they are the gravity fed style, are too restrictive for our systems and really aren't needed. If you are having that much of a problem with deposits, I think it's best to take another look at your tank.

 

[JTGS850GL]

What he said^

 

[eil]

Does the fuel you use contain ethanol (even in low volume like 10%)? I read somewhere that ethanol can cause all sorts of problems.

Not to start YAET (yet another ethanol thread), but...

While I would certainly prefer to be running fuel with zero ethanol (for mileage reasons and political reasons), the truth is that 10% doesn't hurt these bikes at all. It's almost impossible to buy pure gas in the U.S. and almost everyone on this forum has been motoring around for decades on regular unleaded 87 octane 10% ethanol gas with no problems even remotely attributable to the gas.

And to the OP, yeah, sounds like rust. My carbs had a bit of that in them. Maybe it's coming from the fuel sending unit? Or inside the air box?

 

[Call Me Ahab]

Most fuel filters you can get, unless they are the gravity fed style, are too restrictive for our systems and really aren't needed. If you are having that much of a problem with deposits, I think it's best to take another look at your tank.

I'm afraid you're right... I'll have to get one of my cars running again before I can attempt it, but I'll get to work on this asap.

As for the filters, good to know - I'll see about repairing the fuel sock inside the tank. Thanks!

Not to start YAET (yet another ethanol thread), but...

While I would certainly prefer to be running fuel with zero ethanol (for mileage reasons and political reasons), the truth is that 10% doesn't hurt these bikes at all. It's almost impossible to buy pure gas in the U.S. and almost everyone on this forum has been motoring around for decades on regular unleaded 87 octane 10% ethanol gas with no problems even remotely attributable to the gas.

And to the OP, yeah, sounds like rust. My carbs had a bit of that in them. Maybe it's coming from the fuel sending unit? Or inside the air box?

I didn't even think about the sending unit... I checked the airbox, pulled it apart and looked it over. Aside from a few air leaks I didn't know I had, it looks fine. Nothing in there that looks like it could be causing this issue.

I'm planning on replacing the fuel lines on both bikes this week and looking at the petcocks on each bike to see what can be done about those fuel socks - I know for certain that the gs1000's sock is gone, I'll see about replacing it with something. I'm hoping these can be fixed.


Thank you all so much for the input! I'll get to work on these issues as soon as possible, also good to know about the ethanol, I never was certain what effect it had. I'll look into the cost of the pure-gas and compare each, if its economical I'll try a tank or two.

You folks have a great week! Thanks again!

 

[JTGS850GL]

Replace the petcock with a new one. Do it and it will last another 30+ years. By not replacing it you risk issues with the float valves cropping up and biting you. That along with a good tank cleaning will probably fix the brown stuff in the fuel system as well.

 

[Steve]

..., also good to know about the ethanol, I never was certain what effect it had. I'll look into the cost of the pure-gas and compare each, if its economical I'll try a tank or two.

Trying to find pure gas is, indeed, a noble quest, but think about this, ... what happens when you are out on a longer ride and have to re-fill your tank? :-k

Chances are, you will not be within riding distance of another "pure gas" station and will have to fill up with <gasp> ethanoled fuel </gasp>.

What have you gained? Virtually nothing.

A few years ago, I happened to be in an area of Mississississippippi that had a "pure gas" station, so I tried it. Keep in mind that I log every drop of gas that goes into my van, so I have a reliable database to reference. Over three consecutive (full) tankfuls, my gas mileage was virtually unchanged. The little bit that it did go up was not enough to offset the extra cost of the gas, so my cost per mile was just a bit higher with "pure" gas. The van did not start any easier. It did not run any cooler. I could not tell that it had any more power. In other words, I saw absolutely no benefit from running "pure" gas in my van (which is fuel injected). With a carbureted bike, it might be a different story, but I tried the same thing with my Wing, also, and saw no difference.

Be sure to let us know what YOU find. :encouragement:

.

 

[Grimly]

I haven't take a carb apart that didn't have some light brown deposits in it, and that's going back four decades. Obviously, it comes from somewhere, and I suspect the fuel storage and tranportation facilities, that go back a long time, in some places, have a lot to do with it. That's why I always use inline filters - to not use them is ignoring the fact of contamination of fuel, regardless of the state of your own fuel tank.
The small widdly little filters sold for bike use are nearly useless though; I fit much larger ones.

 

[Call Me Ahab]

All righty -

So, since the last post, the bike stalled and wouldn't start. This was due to one of my rectifier wires coming loose, draining the battery - so this was easily fixed. Anyways, this made me uneasy so I pulled one of my bowls off and sure enough, more of that stuff in the carbs. Only a little... a fingertip's worth of the stuff. Half a pea? small dab of stuff, anyways. I seriously don't think this is rust, this stuff was completely white once the fuel dried up, and it's almost crystalline, less fibrous than I initially thought. What could possibly be crystallizing that quickly? Could I be picking this up from my gas station? Could this be from a tanker that filled the tank?

I did not have my phone on me at the time or I would be posting the picture - I'll take photos of whatever comes out of the other bowls.

 

[Grimly]

It's dried rust, pigeon guano, and filling station attendants' sandwiches.