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2001 F4I problem :(

Old 05-05-2010, 02:26 AM
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Default 2001 F4I problem :(

Hi all,

I bought an 01 f4i with 7k about 5 months ago and i have about 9k on it now. It was running fine until it progressively started to lose power and bog. Now when I start up it revs at about 1k and idles like crap. It will bog down with more than 1/4 throttle until i reach about 4k rpms. From 4k to about 10k it pulls as normal and above 10k it makes no power at all but continues to rev up. I have to feather the throttle to get it going most of the time :/ I am not throwing any FI codes when riding or when i jump the wire by the ECM. Gas mileage has stayed the same or even got better (its running really lean).

So far i have:
replaced plugs (even though old ones were fine)
cleaned the K&N air filter (which was already clean)
inspected exhaust system
tested TPS with multimeter
tested MAP with multimeter
changed battery
used fuel injector cleaner

I brought the bike to the honda dealership and they said it was from my slip on muffler which i cant see how a after market muffler progressively leans out a bike.

I am running out of ideas only thing i can think of is fuel lines or fuel pump :/ Can anyone help ?

Old 05-05-2010, 02:39 AM
bubba_finch07's Avatar
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Join Date: Dec 2008
Location: Tallahassee, FL
Posts: 880

Make sure all the plugs are firing, check the injector pluses are correct and the injector isnt stuck open. Test fuel pump. Besides that I'm out of ideas
Old 05-05-2010, 02:42 AM
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how would i go about checking injector pulse and fuel pump ? i have the service manual but cant find how to test these two.

Old 05-05-2010, 04:40 AM
Join Date: Apr 2010
Posts: 32

Check your FPR (Fuel pressure regulator).

It's located under your tank backward (towards the seat) of the airbox towards the clutch side of the bike. Simply pull the vacuum line off...if there's fuel in it it's bad.


-Make sure you gapped your spark plugs properly, and make sure they are properly torqued into the head.
-Make sure none of your fuel lines are kinked
-If one of your injectors was stuck open the bike would run like ***
-Test coils (Pull boot off spark plug, stick wire into boot, put other end of wire near frame. You should see a nice pretty spark when it's about 1 inch away. If it looks really dim and you have to put the wire very close to the frame, your coilpack might be done. Don't touch anything metal on the bike, or you'll get a nice zap.


Last edited by Duo Maxwell; 05-05-2010 at 04:45 AM.
Old 05-05-2010, 04:10 PM
R Dub's Avatar
October 2011 ROTM
Join Date: Feb 2009
Location: Burbs of Chicago
Posts: 1,340

Do you have a power commander on it? I do not have one nor do I have much experience with them but I hear they can make your bike do some weird things.
Old 05-05-2010, 04:31 PM
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x2 on FPR... very common problem for f4i's
Old 05-05-2010, 09:25 PM
RunwayOneSix's Avatar
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Originally Posted by R Dub View Post
Do you have a power commander on it? I do not have one nor do I have much experience with them but I hear they can make your bike do some weird things.
Have a power commander usb on mine and I have yet to notice anything weird.
Old 05-05-2010, 10:35 PM
July 2010 ROTM
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Location: arkansas
Posts: 1,150

the pc's can do weird things, its true, but they usually arent very tempermental. check the fpr just to check it but if it was bad youd be running rich, not lean. ummm do u have a stock exhaust or a pc? put the stock exhaust on or switch to a zero map and see if that changes anything. if it does it will help to narrow down the problem.
Old 05-06-2010, 08:47 PM
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thanks for all the responses
i dont have a power commander and il be checking FPR this weekend (i didnt think it could make it run lean but it is one of the few things i havent checked) and all the plugs / coils and fuel lines. Il let everyone know how it goes

thanks for the help

Last edited by rmarinar; 05-06-2010 at 08:52 PM.
Old 05-09-2010, 01:31 AM
Join Date: Mar 2010
Posts: 95

im having a similar problem with my f4i except i had some rust problems in the tank the guy let is sit for mothns with just a little gas in it i cleaned it all out now i gotta change the filter
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