phoenixfire Posted October 3, 2012 Share Posted October 3, 2012 Hi all, What would you suggest to check for when you have symptoms of a rich smelling exhaust? A few weeks ago I noticed a a strong gas smell from the exhaust. The smell is constant throughout riding the bike and remains after start up. The oil level is fine and the inside of the pipe is not oily. She idles and runs normal. The only difference I can tell is the smell and perhaps some reduced fuel mileage (although I've also changed my sprocket configuration to 16/43 so not sure if the extra fuel cost is in part / solely because of that). I had yet to change the plugs and air filter since getting the bike from the previous owner so I changed both and they both seemed nearly spotless IMO. I attached pictures, please offer your opinion on their condition. Still after all that the smell remains. Any help / input would be appreciated. Link to comment Share on other sites More sharing options...
Forum CEO HispanicSlammer Posted October 3, 2012 Forum CEO Share Posted October 3, 2012 A few items that can cause the bike to run a bit rich, if the bike does not warm up enough it will run rich.Yours has a manual choke but if it was a later model the wax unit could be burst and cause it to run rich. A faulty thermostat will keep the bike too cool and it will run rich, a faulty fuel pressure regulator will definitly give you a bad fuel load, air filter clogged, or vacuum hoses undone from the map sensor, or to the airbox. Lots of things to look over. Clogged injectors too, could be not atomizing the fuel load enough and squirting jets instead of mist. Link to comment Share on other sites More sharing options...
Member Contributer kaldek Posted October 3, 2012 Member Contributer Share Posted October 3, 2012 if it was a later model the wax unit could be burst and cause it to run rich. Wax unit only controls air bypass at idle, it wouldn't affect richness with the throttle open. Link to comment Share on other sites More sharing options...
Member Contributer AnikMankar Posted October 4, 2012 Member Contributer Share Posted October 4, 2012 lift your tank and pull the choke lever on the right side ..sometimes the mechanism gets jammed... had a similar problem and finally disconnected the choke cable...(never used it). change the fuel and see if the problem persists ...also is the blacking of the plug on only one cylinder / plug ? Link to comment Share on other sites More sharing options...
phoenixfire Posted June 7, 2013 Author Share Posted June 7, 2013 I'm going nuts. I've taken my bike to two different mechanics, both who are highly reputatble. This rich exhaust smell is still happening. Both mechanics said "its a 99, engines just start to stink after a while". But I can't accept that answer. The smell has gotten stronger in the last few weeks and my fuel mileage has PLUMMETTED! - I'm getting about 140km (87 miles) / tank - which is about 7km / L / 26 miles / gallon! I went for a ride without my earplugs and noticed a sound. There's a rattle / farting sound whenever I engage the throttle. I've tried it see if I could hear it when the bike was going a good speed without the throttle engaged and it's definetly only there when the throttle is engaged and shortly after it's closed. I re-checked the air filter and it's spotless. I checked the choke cable like Anik said and it's fine. Before I take a wrench to it, does anyone have any other ideas of where I should start with this new information? Link to comment Share on other sites More sharing options...
Member Contributer kaldek Posted June 7, 2013 Member Contributer Share Posted June 7, 2013 Your mileage is so bad I don't see it as a fuel measurement problem, it really looks mechanical failure of a fuel injection component. So, assuming your problems aren't caused by incorrect fuel *metering* by the ECU, let's look for some mechanical failures. Check for problems with the fuel pressure regulator diaphragm for starters. Pull off the regulator vacuum hose with the engine running and see if any fuel leaks out of the regulator. If it does, it's stuffed. I would also check the actual fuel pressure (warning - requires pressure testing kit and special bolt from Honda to create a T-junction in the high pressure fuel line). Pressure regulators are cheap, so don't worry if yours is busted. But PLEASE use good safety around fuel. Fuel pissing out of a busted regulator onto a hot engine is not my idea of a good time. Also check for leaking fuel injectors. If they're leaking, fuel will come out when they are closed - see my video below on how to do that. Link to comment Share on other sites More sharing options...
Member Contributer Cogswell Posted June 7, 2013 Member Contributer Share Posted June 7, 2013 All great advice. After you've given the injectors 'the finger' , even if they're not leaking they still can have crappy spray patterns. Once you have the airbox off, you've done most of the work - removing and replacing the injectors is easy. You can send them off to Marren Fuel Injection in Connecticut for service - they're about $25 per. https://www.injector.com/injector_service.html Even if it's not the problem, it's still good maintenance to get the deposits out of them - after 14 years there's probably some junk in there. Doing this went a long way toward reducing the stumbling / surging on my 6th gen. Link to comment Share on other sites More sharing options...
phoenixfire Posted June 30, 2013 Author Share Posted June 30, 2013 So it turns out my milage problem was that I was putting around the city too much. I finally got the bike outside of downtown and nearly doubled my milage! I got 270 km / 167 miles on a camping trip. I knew city riding reduced milage but wow what a contrast! I took the bike back into the shop - did a valve check (nothing needed adjusting whew!) and put it on the dyno. The computer is showing all systems are normal. So now comes the question - has my nose just gotten more sensitive? Or is it something along the lines of carbon buildup in the exhaust that's causing the smell? Link to comment Share on other sites More sharing options...
Member Contributer Switchblade Posted June 30, 2013 Member Contributer Share Posted June 30, 2013 SeaFoam it ........ Link to comment Share on other sites More sharing options...
spud786 Posted June 30, 2013 Share Posted June 30, 2013 You really didnt show the part of the plug we need to see, does sound like its rich, by the milege, even in town 26 is very bad, 167 miles for a tank is around the mid 30's at best, but if your center elctrodes are dark brown, then Id say its richer than it needs to be. You never mentioned if the bike is totally stock Link to comment Share on other sites More sharing options...
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