Hey guys i have an 02 f4i and i am having some serious problems getting it running right, the symptoms:

no auto choke ( probably unrelated )
very slightly erratic idle
when warm and idling it bogs / hesitates when throttle is whacked open
wont rev past 9-10k


things i have tried:

new fuel pressure regulator
new fuel pump / filter
new spark plugs
checked air filter for clogs


Does anyone have any ideas to test before i take her to the shop? Been messing around with this for around a month now and i really just want to get out and enjoy the weather...

 

You've replaced the fuel pump, but do you have a way of checking what the actual fuel pressure is. At idle it should be 50psi. Poor performance and driveability is one of the symptoms listed for a faulty pressure regulator.

 

fuel pressure regulator was the very first item i replaced trying to fix this problem, i cannot test fuel pressure without the honda specific tool or spending a bunch of money adapting a car pressure gauge

Ty for the post, i really do appreciate it!

 

Dooh !!

Don't know how I missed that... it's late I guess.

 

Its cool man, i really appreciate you taking the time to try to help me.

 

How did this issue come up ? What is the history of the bike ? Did this happen over time, or suddenly start happening ? This will help with an overall picture of the situation. FI bikes aren't my forte, but it's still a motor right...

 

Its very interesting how this happened, i first noticed the bike was losing power in the lower rpms, it still revved fine up high but my gas mileage was shot. big red flags for the FPR being bad

Replaced the fuel pressure regulator and thats when i got these serious problems, i find it very hard to believe that the brand new OEM FPR is bad but maybe i should try putting the old one back on..?

 

The Fuel Pressure Regulator is a fairly basic device. It uses vacuum from the intake manifold to regulate the fuel pressure. I'd be more inclined to suspect a vacuum hose leak going to that regulator than an actual bad regulator. This would also account for a rough idle. It certainly can't hurt to put the old one back on though.

 

I have been thinking it might be a vacuum leak, the vacuum hoes goes through a couple of t valves splitting it up for all the cylinders, is their an easy way to see if the whole assembly is leaking?

 

I understand that some people have used starting spray to detect a leak. With the engine running, spraying the starting fluid near vacuum hose joints will affect the engine speed if there is a leak present. Naturally use caution when attempting this procedure.