:bs:
- 6 months ago my GS started the dreaded fuel starvation issue, so I took it into a shop.
They cleaned everything, added a new fuel filter and new fuel lines for me, as per my request.
- I left the shop and got about 3 miles and it died...again. Took it back and they replaced my petcock altogether.
- Picked it up and rode in-town speed (stop & Start) for 3 months, no issues. I took one trip up the interstate for about 15 minutes and, yep, you guessed it, fuel starvation. Dead on the roadside.
- I took it back AGAIN and told them to keep it for a month. Today I went to get it and they said that they cannot figure it out. They did a bench test and said that the CO2 levels dropped at 3/8 throttle when they put a drag on it (lightly pressing the rear brake to imitate load). Apparently the vacuum is dissipating at higher RPM, thus allowing the petcock to shut. I don't get it.
Also, the engine 'surges' and 'sputters' during normal, 40-50 MPH operation.
- Now the suggestion is to put a jet kit in it, but no guarantees. That would put my repairs for the same mother ^$&&$ problem to $1000 total. No way, man.
I'm out of answers, as well as questions. I've got nothing. Any ideas?
I had same problem 8 months ago. Sputtering and cutting out on the highway, herking/jerking feeling, it had been present when i first got bike, but thought it was bad front tire or something... then it worsened and became clear it was an engine issue eventually, few times i was low on fuel, assumed it ran out of fuel, by the time i pushed it to a gas station it would fire up and run again... usually ten minutes on side of the road and it would be ready to start again.
I replaced frame petcock with a honda250 dirtbike petcock - it got a little better.
I found tank petcock screen clogged - replaced it - it got a bit better.
Replaced all fuel hoses - no change.
Replaced carbs with carbs off newer bike - worse ('new'er carbs must have had their own issues) - put original carbs back on.
Banged head on wall - no change.
Replaced pilot and main jets (to recommended stock upsizes) - barely a bit better.
Found the carb float level inconsistent, found float valves getting stuck closed -- replaced needles/seats - 100% better.
Oh and found my fuel was bad (well... i think it was bad) and coated most everything with bad gas glaze-- liberal amounts of stabil in tank from now on.
Not saying it is necessarily your needles/seats... but maybe.
Either way, you're not alone... it is very frustrating.
My total cost came to about $500; doing the work myself.
:woohoo:
Cool. Thanks! That is encouraging.
I will tear the carbs down and try the seats and needles.
\m/
Woah woah woah....
Check your float level first.
Clear U tube it.
Quote from: gilaman on October 08, 2011, 05:46:47 PM
:bs:
fuel starvation issue
Apparently the vacuum is dissipating at higher RPM, thus allowing the petcock to shut. I don't get it.
Also, the engine 'surges' and 'sputters' during normal, 40-50 MPH operation.
Did they replace your vacuum tube when they replaced all the hoses? At first it sounded like the infamous 'bad petcock' in regards to the highway speed malfunctioning, but you said they replaced the petcock (new or used?) so that can't be it. Honestly, I would check the float levels first (its free), and then get a vacuumless petcock setup and see if that solves your issues. Are you sure they routed the hoses right, and that your tank petcock is open fully? I'm pretty skeptical on who works on my bike, especially if they don't own a gs500 themselves and know the little quirks and foibles.
They added a new fuel filter... do you mean they put a fuel filter in where one had not been, or they replaced an existing fuel filter with a new one? (This is in addition to the tank filter/screen thing right?)
Have you tried the bike without a fuel filter? A lot of fuel starvation issues are Because of the fuel filter - it restricts flow and can cause starvation.
Michael
Quote from: mister on October 08, 2011, 08:05:40 PM
They added a new fuel filter... do you mean they put a fuel filter in where one had not been, or they replaced an existing fuel filter with a new one? (This is in addition to the tank filter/screen thing right?)
Have you tried the bike without a fuel filter? A lot of fuel starvation issues are Because of the fuel filter - it restricts flow and can cause starvation.
Michael
This. A clogged filter/binded fuel line is the first thing I check before getting my hands dirty. Always check the simple stuff first.
Quote from: gilaman on October 08, 2011, 05:46:47 PM
:bs:
I'm out of answers, as well as questions. I've got nothing. Any ideas?
If I were in your place, I would temporarily install fuel line straight from tank to carb inlet at the T ... bypassing all the stock fuel lines and frame petcock - put at least a hundred miles on it like this, freeway and in-town ...(You can install an inline filter and cut-off valve as well - I've never had an issue with inline filters)
If the same symptom re-occurs then you know it's not fuel starvation (surely the shop made sure the in-tank fuel screen is clean ? ?)
valve adjustment?
Actually, I did have a valve adjustment done, but no changes.
Can anyone recommend a carb specialist to send these carbs to?
:thumb:
Upon further review...it seems as though I need to talk to buddha...