Hello,

OK, I am not about to ask one of those silly questions, espesually ones like my bike is sputtering at an idle, or it cranks and won't start! This is definitely a problem that needs to be adressed by a certified technician, or someone with fuel injection knowledge. Please be advised, I am very knowledgable with motorcycles, have ridden and raced for years, and was an industrial mechanic back in the 70's. I am just not familiar with fuel injected motorcycles, and have a real problem that I can't figure out. Here goes from the start: I bought an 02 F4i recently that had been sitting for about a year. I charged the battery and it cranked just fine, though just wouldn't fire. I finally got it to start the next day after bringing it home, it ran fair though was loading up at an idle. The fuel in the tank smelled like varnish, so I drained the tank, cleaned it out thouroughly, and filled it with new premium gas. I also installed four new factory required NGK spark plugs and cleaned the air filter. It immediately started and ran better, though the FI light keeps flashing and then after a short while, started loading up again. I let it sit overnight and then tried to re-start it the next day. The number 2 cylinder was full of fuel and actually locked the motor when cranked. I pulled the plugs again, drained it and replaced the number 2 injector with a used injector off another 02 F4i from a M/C salvage yard. It still is loading up and I have tried three different used injectors. I also tried unhooking the battery cable to clear the computer to no avail. Each injector I install on number 2 cylinder seems to make the bike run differently, and they don't all leak fuel down into the cylinder. So I finally bit the bullet and just bought a new injector from Honda. It still does the same thing, so I'm assuming the computer may possibly be bad? The strange thing is that the number 1 and 4 cylinders are burning correctly, and the 2 and 3 cylinders are gas fouled and appear to be the ones fouling plugs. Are there any sensors like a map sensor, or maybe a fuel pressuer regulator somewhere on the bike that could be the problem? I just don't know what to do and the local bike shop is backlogged about three weeks. Please give me some advise and steer me in the right direction. Thanks in advance, Chris

 

yeah your fuel pressure regulator is on the fuel rail it kinda looks like a little bell and has a vacuume line the diaphragm in it is probably bad pumping gas into you cylinder via the vacuume line you can test it by using a mighty vac thats where i would start also count the blinks on the fi thats the code you popped if it doesnt come up you can jump the 2 pin connector under the seat and that will make the codes come up one long flash is = 10 on short = 1 give me the codes and ill look them up for you tomorrow when im at work

 

that is odd. Especially since there isnt any fuel in the injector until the fuel pump kicks in the pressure. As soon as your bike is shut off... so is the pressure and so the gas flow to the injector. I would almost suspect the gas tank vent tube. If its plugged, it may continue to build up pressure in the tank from the suction of fuel pump, then when you shut it off, the pressure isnt relieved and it forces gas through the injector. The number 2 injector may just be the least path of resistance in this case. With the odd pressure build up, it may trigger the fi light.

Just something else to consider if what Hondatech68 said doesnt pan out, but I would go with his suggestion first.

 

do these bikes share a coil for 2 cylinders or did they have the coil-on-plug setup by then? I ask because I've seen 4 cylinders that share coils for 2 of the cylinders have similar problems when a coil start to get weak. Not the fuel filling problem, but the shared plug fouling issues.

 

I can pretty much assume it's the fuel pressure regulator, if you look at the vaccum line to it, it "tee's" into cyl. 2 & 3 ports just below the butterflys. The real easy way to check this is pull the vaccum line off the FPR, hook another hose to it and put it in a container or route it back into the fuel tank up top or whatever and prime the fuel pump. If fuel sprays out of it, you need a new FPR. Injectors spray such a fine mist of fuel, you'd have to crank that thing for an hour or two to gas lock the motor, not to mention have a flat cam because the intake valves would have to stay shut for all that cranking!

Later