waltea469

Alright, about two months ago I went on a four hour trip on my F4i, and I thought it fouled a spark plug, so I put a whole new set of plugs in it (most of you know that this isn't cheap), figured this would fix the problem. It didn't; the damn thing fouled the whole new set this time. By this time I knew it had to be something else. I ran through most of the standard checks: fuel pump, injector spray, every single resistor you can think of, fuel filter, fuel pump regulator, changed the gas, checked spark, and compression. Everything checked out. I then reluctently took the thing to a honda dealer to have it fixed; well they don't know what's wrong with it either. Said they had 9 hours in it, 3 of which they were on the phone with honda themselves. So now I have a bike sitting in my garage that doesn't run worth a ****, and nobody, not even honda themselves know what is wrong with it. All I know is that it is running entirely too rich, fouls plugs, and will not start without throttle when it's warm. I'm sure that it is something really stupid that everyone is overlooking. So any help would be greatly appreciated.

standy

Check all the vacuum hoses that run to the throttle bodies. I have seen fuel pressure regulators fail on some CBR's lately. Usually the symptom will be close to what you're describing......alot of times it will only run on 3 cylinders until you have the throttle almost wide open. The easiest way to check would be to pull the vacuum line off the regulator, turn the key on to start the fuel pump, and watch the end on the regulator where the vacuum hose connects. If it drips any fuel, its bad.

yzfrone

wanna sell the motor?
haha

sounds like a blown ECU and very bad timing

SIC Nate

check the throttle position sensor

waltea469

I have checked and the dealership has checked all the sensors, and everything checks out. Honda did however say something about a blown ECU but the dealership said that was a fat chance. The vacuum hose on the fuel regulator; I will check that out hopefully that is all it is.

Thanks for the input guys.

MikeM

Do you have access to another f4i to start swapping parts?

waltea469

I'm afraid I don't, unfortunatley I figure I'm pretty much screwed. Stupid things got me stumped.