I have a 1994 Suzuki GS 500 that had a stock petcock problem-fuel starvation issues. Lots of helpful advice from members (on my January posting) on how to replace it with the 2004 Honda CRF 250. I did the replacement about a month ago and all went well-thanks.
It's now late spring and I've had the bike out 4 or 5 times with the Honda petcock-working great until today.Bike starts losing power at 50-60kph and then conks out-similar to fuel starvation situation.I managed to restart it and make it back home after a few stalls. I could only keep the bike going if the choke was on and not too much throttle,otherwise it would die again.
On the advice of a friend who rode a bike 50 years ago,I tried leaving the gas cap open and everything worked well-i.e. an "air starvation problem"??
Any suggestions on how to deal with this? Could it still be related to the petcock-I closed off the vacuum hose with a plug that used to fit onto the old Suzuki petcock.
Thanks Leon
Toronto,Canada
plugged tank vent
tank vent cleaning how-to straight from the wiki
http://gstwins.com/gsboard/index.php?topic=41061.0
OK,so I cleaned the tank cap vent (as suggested by 2 contributors) according to the wiki instructions and added some more gas to make sure it wasn't a low fuel problem-but the "bogging down and dying"problem still occurs, especially after the engine has had some time to heat up after a few minutes.
Then I opened the gas cap (as done previously) and the bike seemed to work better again for awhile but then started stalling/dying again after a few minutes. I managed to start it again using the choke at maximum and get home only by using the clutch to control bikespeed-any attempt to use the throttle or to reduce the choke setting and the bike conks out.
Any further suggestions (carbs were cleaned,float bowls replaced,etc.last winter in a vain attempt to solve the fuel starvation problem)? Should I consider going back to my old stock petcock and just run it on prime or is this an unrelated new problem?
Getting desperate
Leon
Quote from: lf2503 on June 01, 2010, 08:53:47 PM
OK,so I cleaned the tank cap vent (as suggested by 2 contributors) according to the wiki instructions and added some more gas to make sure it wasn't a low fuel problem-but the "bogging down and dying"problem still occurs, especially after the engine has had some time to heat up after a few minutes.
It does this even at idle? Is the problem the same with the petcock set to PRI? (comment: I'm not familiar with the CR250 petcock. Is there a diaphragm? It may just be on/off - in that case, make sure it is on.)
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Then I opened the gas cap (as done previously) and the bike seemed to work better again for awhile but then started stalling/dying again after a few minutes. I managed to start it again using the choke at maximum and get home only by using the clutch to control bikespeed-any attempt to use the throttle or to reduce the choke setting and the bike conks out.
So, not at idle but when riding? (Why are you riding without letting the bike warm up?) Did you close the cap again, or did it struggle even with the cap open? If it worked with the cap open, and struggled when you closed it again then the cap cleaning needs to be redone.
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Any further suggestions (carbs were cleaned,float bowls replaced,etc.last winter in a vain attempt to solve the fuel starvation problem)? Should I consider going back to my old stock petcock and just run it on prime or is this an unrelated new problem?
Getting desperate
Leon
It's pretty hard for a petcock to go wrong. Especially at idle/low rev conditions when the fuel demand is quite low. You can check if fuel is getting to the carbs by draining the float bowls, waiting, draining again (petcock on PRI). If there is fuel in the second draining, the petcock must be flowing gas.
It is more likely that your problem is somewhere other than the frame-mounted petcock. Here's where I'd look:
- if vac line was disconnected for new petcock, make sure it is capped off properly
- drain gas tank and fill with fresh fuel (there may be water in the gas)
- make sure there is enough gas (an empty tank will look like it has plenty of fuel)
- make sure under-tank petcock is fully open (check wiki and other posts for photos)
- make sure all fuel lines are routed correctly (again, check wiki and posts from gsJack)
- make sure all fuel lines are free (not kinked, bent, pinched under the fuel tank etc)
also make sure the tank vent tube is not kinked or clogged
Sounds like maybe your bike is developing a serious vacuum leak when it gets hot, as evidenced by need for choke and very light throttle to keep it running. Maybe cylinder head needs re-torque .
Are u losing both cylinders ? How do ur plugs look ?
Also, check the floatbowl vent tube (if it's there). It allows atmospheric pressure to the fuel in the floatbowl.
Pull a fuel line off a carb, put it in a container, switch petcock "on" and see if you get good fuel flow. +1 on checking the petcock under the tank is fully "on".
engines need 3 things fuel air spark. you have all 3. sounds like clogged air filter,or float level too high more likely. pull plugs and read. do a float height check. start with common,simple and easy problems to fix first. get new plugs anyway, like $5 for 2. maybe try to run with air filter off and listen for difference
I want to thank everyone who sent in their suggestions-I checked out almost all the possibilities mentioned and nothing seemed to help.
So after a few more wasted hours,I switched back to my old Suzuki petcock (I even cleaned that out with silicone lubricant). Of course the bike died shortly when the valve was turned to 'ON' but worked when I ran it on 'PRIME'.
So I guess I'll run it on 'PRIME' and turn it to 'ON' when the bike isn't being used and make sure I don't run out of gas because there is no reserve-at least that seems to be the consensus for those riders that didn't switch to the Honda CRF250 petcock valves.(This was also the advice the bikeshop owner gave me when even he couldn't figure out was wrong after doing $450 worth of carb cleaning,float replacement,new spark plugs,etc.!)
I'm still curious as to why the Honda petcock seemed to work so well for a few days and then caused problems? (In fact, when I bought the bike with the Suzuki petcock,it also ran fine for awhile until the "fuel starvation" issues started.)
Once again,thank you to all those who responded-it's great to have a forum like this,especially for newbies and non-technical types like myself.
what's the condition of the tank itself? maybe there's debris getting through the lines but not through the petcocks?
OK the tank was emptied out and new gas put in. I drove the bike today for 15km with the petcock on PRIME and then it died. I put the choke on full and it started,but any attempt to use the throttle or lower the choke resulted in the bike dying again. However even this didn't last long, and then I couldn't even start the bike with the choke on-next came the humiliating tow back home (luckily that was free with my CAA membership).
After reading the forum,it was suggested that the main jets are clogged-this sounds like a bigger job than any of the other remedies I've tried.Any other simpler possibilities or should I attempt to clean the main jets? (BTW the bike was stored over the winter with fuel stabilizer).