This is quite lengthy. Sorry in advance.
I have a 2008 Shadow Aero 750 that I purchased back in 2011. I use it to commute to work rain or shine and I've raked in 64k miles on it and a problem have developed June of this year. I started the bike one morning, choke on, and while the bike was warming up I heard the RPMs drop and then the engine dies. The bike will crank and crank but will not fire up. So far this has happened 5 times since June and always in the morning.
The first time this happened, I had the bike towed to a Honda service center. They cleaned out the jets and checked the carb for any problems. No problems found. The bike ran fine for 4-5 weeks.
Then the problem happened the 2nd time. Took it back to the same Honda service center. The mechanic discovered that the vacuum hose to the petcock is cracked and is leaking air. Replaced the hose, the bike started up and ran fine for 2 weeks. The battery was also charged but only charged to 20%.
Then the problem happened the 3rd time. I tried to troubleshoot it myself and removed the breather tube from the tank since I read somewhere that sometimes a vacuum can develop in a tank if the breather tube is clogged. I blew into the breather tube leading to the evap canister and plugged it back to the tank. Started the bike and it fired up! Took it back to Honda service and they suspect that the problem could be the Evap canister since I've been overfilling the tank for the past 3 years. They suspect a vacuum is being created preventing the fuel from flowing to the carb. they cut a small hole on the breather tube and the bike ran fine for 5-6 weeks.
Then the problem happened the 4th time. This time I definitely drained the battery trying to crank it over and over out of frustration. I replaced the battery, removed the gas tank and checked the hose that goes to the evap canister to make sure it wasn't blocked. Yes, I blew into it too. Put the bike back together and it ran fine for 3 weeks.
Then the problem happened the 5th time last week on Monday. I decided to disconnect the fuel line from the petcock. I felt air blow out at my thumbs as the fuel line disconnected from the petcock. Pressure in the line? or could it be a vacuum? I'm not sure. I reconnect the fuel line back and the bike fired up right away and I've been riding it for 2 weeks without any problems.
Obviously the fuel is not getting to the tank when this happens and there is pressure in the fuel line. What gets me is what could possibly be causing this? Its so intermittent and only happens in the morning and the bike runs for weeks like nothing happened until it just comes back again!
Has anyone experienced this? Honda service dept is stomped and not even sure what to check for next.
So far I've ruled out dirty carbs/jets, battery, vacuum line to petcock, breather hose is not clogged.
Any ideas?
I have a 2008 Shadow Aero 750 that I purchased back in 2011. I use it to commute to work rain or shine and I've raked in 64k miles on it and a problem have developed June of this year. I started the bike one morning, choke on, and while the bike was warming up I heard the RPMs drop and then the engine dies. The bike will crank and crank but will not fire up. So far this has happened 5 times since June and always in the morning.
The first time this happened, I had the bike towed to a Honda service center. They cleaned out the jets and checked the carb for any problems. No problems found. The bike ran fine for 4-5 weeks.
Then the problem happened the 2nd time. Took it back to the same Honda service center. The mechanic discovered that the vacuum hose to the petcock is cracked and is leaking air. Replaced the hose, the bike started up and ran fine for 2 weeks. The battery was also charged but only charged to 20%.
Then the problem happened the 3rd time. I tried to troubleshoot it myself and removed the breather tube from the tank since I read somewhere that sometimes a vacuum can develop in a tank if the breather tube is clogged. I blew into the breather tube leading to the evap canister and plugged it back to the tank. Started the bike and it fired up! Took it back to Honda service and they suspect that the problem could be the Evap canister since I've been overfilling the tank for the past 3 years. They suspect a vacuum is being created preventing the fuel from flowing to the carb. they cut a small hole on the breather tube and the bike ran fine for 5-6 weeks.
Then the problem happened the 4th time. This time I definitely drained the battery trying to crank it over and over out of frustration. I replaced the battery, removed the gas tank and checked the hose that goes to the evap canister to make sure it wasn't blocked. Yes, I blew into it too. Put the bike back together and it ran fine for 3 weeks.
Then the problem happened the 5th time last week on Monday. I decided to disconnect the fuel line from the petcock. I felt air blow out at my thumbs as the fuel line disconnected from the petcock. Pressure in the line? or could it be a vacuum? I'm not sure. I reconnect the fuel line back and the bike fired up right away and I've been riding it for 2 weeks without any problems.
Obviously the fuel is not getting to the tank when this happens and there is pressure in the fuel line. What gets me is what could possibly be causing this? Its so intermittent and only happens in the morning and the bike runs for weeks like nothing happened until it just comes back again!
Has anyone experienced this? Honda service dept is stomped and not even sure what to check for next.
So far I've ruled out dirty carbs/jets, battery, vacuum line to petcock, breather hose is not clogged.
Any ideas?
