F4 problems

Started by rrwantr, May 15, 2003, 02:42:26 PM

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rrwantr

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A friend and I were doing a trackday yesterday and he had some problems with his 99 F4 after lunch.  Prior to lunch he had said that it didn't seem to be pulling as much when on the throttle.  At lunch filled up with gas and on the next session in the first lap it started sputtering and even with more throttle gradually lost speed and eventually died.  Was able to start and get back to the pits.  We pulled the fuel line and it seemed like there was some water in the line so pulled the tank, drained it, drained the bowls and made sure that fuel flowed through the lines and filter...then put the tank back on and filled up with different gas.......went out and it did the same thing.... Any ideas on what could be the problem?  I told him to replace the fuel filter...and then follow all the wiring to check for loose/bad wires.  Could it be an ignition problem?  Would a bad reg/rec cause this?  Thanks for the help.  Don't believe it's a venting problem as no "whoosh" when the tank was opened.  Also he said that it happened in the same place both times before he packed it up.  It was after a very tight right hander and happened as he straightened the bike up.... any idears???

MELK-MAN

#1
friend of mine had problems with his 99 f4. it was a "california" model with all kinds of emission stuff. Only had problems when he would wheelie or stoppie though..way down on hp compared to mine on the dyno too. Same dyno, 15hp lower than mine..seeing that your in CA.. this may be a part of the problem. My friend by the way sold the bike.
2012 FL region & 2014 South East overall champion
Pro Flow Tech Performance Fuel Injector Service
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rrwantr

It's purely a track bike and is a 49 stater....so that shouldn't be a problem...thanks for the suggestion

h8mondays

#3
What's up RR haven't talked to you in a while?? I by no means know enough about carbs to be giving biblical advice, but things that came to mind immediately were:

Pull the plugs and see if one or more is fowled out because one of the floats could be getting stuck and dumping gas into a cylinder. Check the jets and make sure they are clean and basically make sure all the internals are where they need to be.

Keep in mind, that I know just enough about carbs to get by and more than enough to get into trouble.  If it were my bike, I'd probably pull them and go through each one thoroughly. Regardless, I hope you get some answers here on the board.

rrwantr

Thanks h8...passed on the info...he's also going to check the catch bottle as someone mentioned that it could have siphoned some water from there...

Bsmedic

Hummmmmm..............

Melk-Man's has 15 more horses. I guess that's the new CBR 636 F4i.

LOL!!!!!

MELK-MAN

#6
QuoteHummmmmm..............

Melk-Man's has 15 more horses. I guess that's the new CBR 636 F4i.

LOL!!!!!

VERY funny and i WISH.. no, my poor buddy with the "CALI" f4 dynod at a meager 84hp...with jetting and ultimate 4 fuel i get a 101hp...
i promise!! see?? http://www.cycleforums.com/forums/showthread.php?s=&postid=431548#post431548
2012 FL region & 2014 South East overall champion
Pro Flow Tech Performance Fuel Injector Service
MICHELIN, EBC, Silkolene, JenningsGP, Engine Ice

MightyDuc Racing

That guy on the 636 sure is fast!  Maybe Melk is zip-tying his bodywork on that guy's bike when he races you heavyweights! ;D
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yamagod

#8
The F4 has a CRAZY fuel pump relay that is controlled by the CDI box according to engine RPM. The pump is always active below 3500 RPM the at +3500 RPM the relay switches to a different circuit. If the second circuit is bad, you can drive the thing around all day below 3500 RPM. But, when you go past 3500 the pump shuts off. I have NO idea why Honda incorporated this in the fuel system (my Regional Service Rep didn't even know it existed) but this may be the cause of your problem. It may just not have failed completely. This is not addressed in the service manual and I had to figure it out by analyzing the wiring diagram. The only real test for it is to get the carbs full of fuel and run the fuel feed line to a container and get the engine RPM to 4000-5000 RPM and see if fuel flow is noticably reduced or replace the relay and hope for the best.
Hope this helps, not to many people know of this problem (including Honda).
Shane Myers
Lake Country Powersports
AM #204

MELK-MAN

QuoteThe F4 has a CRAZY fuel pump relay that is controlled by the CDI box according to engine RPM. The pump is always active below 3500 RPM the at +3500 RPM the relay switches to a different circuit. If the second circuit is bad, you can drive the thing around all day below 3500 RPM. But, when you go past 3500 the pump shuts off. I have NO idea why Honda incorporated this in the fuel system (my Regional Service Rep didn't even know it existed) but this may be the cause of your problem. It may just not have failed completely. This is not addressed in the service manual and I had to figure it out by analyzing the wiring diagram. The only real test for it is to get the carbs full of fuel and run the fuel feed line to a container and get the engine RPM to 4000-5000 RPM and see if fuel flow is noticably reduced or replace the relay and hope for the best.
Hope this helps, not to many people know of this problem (including Honda).
Shane Myers
Lake Country Powersports
AM #204

this is good to know..thanks.
2012 FL region & 2014 South East overall champion
Pro Flow Tech Performance Fuel Injector Service
MICHELIN, EBC, Silkolene, JenningsGP, Engine Ice