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02 VFR won't rev out -> then idles poorly -> now won't start


jim v

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hoping the forum gurus can help figure out what's going on -

 

Bike - 02 VFR800 approx 18k mi, bike is ridden hard, but well maintained

Mods - catless header, micron exhaust, PC3 professionally tuned

 

Symptoms -

Day 1 - after letting the bike sit for all of June - sometimes work and life don't leave time for riding - July has arrived and, finally, I have time to take VFR out for the day. When I start it up, I hear the familiar fuel pump whine but it doesn't have the initial fast idle, still the its idling normally ~1400rpm and I'm so looking forward to the ride that I barely care.  After it warms up, I notice the fueling doesn't seem as smooth as I remember and there's no VTEC crossover. Even worse it won't rev beyond 9000rpm (in 1st, 2nd or 3rd gear, didn't try 4th 5th or 6th). It doesn't seem like its hitting the rev limiter, just climbs slowly from 6-9k and won't spin further even with a wide open throttle. I tried several times and even with fresh fuel (added 2 gallons) the result was always the same. I bring the bike home and park it for the day

 

Day 2 - air filter looks great, battery connections are tight, no FI lights. I try starting it and again no fast idle. Things keep getting worse, it begins idling poorly - ~1000rpm and if I touch the throttle it wants to stall. Doesn't improve as the bike gets warm, the idle keeps deteriorating and eventually it won't idle and now it won't start. I hear the fuel pump and it cranks but no combustion.

 

I'm thinking this might be fuel related - ignition issues should throw a code, right? And since it effects all 4 cylinders maybe its the fuel pump (even though I hear it when trying to start it) or a pinched breather tube?

 

Any info or advice would be hugely appreciated

 

 

 

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The fast idle is a hint. If the coolant passages in the fast idle wax unit get gunked up it sticks. No more fast idle and maybe no more good idle at all. That may have gotten the starter valves stuck partially closed but all air at idle wants to come through them. If the starter valves are sticking, off-throttle will sputter (no matter what speed it is at) then when you give it throttle it has to get past that challenge.

 

VTEC: It may simply not have reached the required temperature for VTEC to kick in.

 

See this post. He detailed the pictures and cleaned it up himself:

 

http://www.vfrdiscussion.com/index.php?/topic/59508-how-the-fast-idle-wax-unit-works/&do=findComment&comment=1034378

 

I think it sits under the mess of hoses in the intake and is quite painful to get to. So you may want to rule out issues by "easiest to get to".

 

Maybe also on the list is fuel pressure regulator? Stuck or damaged sending fuel down the vacuum control hose? 

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Thanks Knight, I'm off to check those threads and videos

 

As for VTEC, it had definitely reached operating temperature. I wait until its warmed up before going past 6krpm

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Water in the fuel could account for many of the symptoms.   Untreated fuel can have the ethanol phase separate and fall to the bottom of the tank as water in as little as 30 days.  If contaminated, adding more fuel will not correct it - the only way is to completely drain it and re-fill.   Nearly all the fuel can be siphoned out with the tank propped up - it might be a relatively easy 1st step before any dis-assembly. 

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Thanks Cogswell, fuel separation could explain a lot of the symptoms except the fast idle no VTEC. Hmmmm.......maybe a combination of problems. In any case draining the tank completely and adding fresh fuel isn't hard to do. Results of that little experiment would go a long towards troubleshooting as so I will give it a try. With luck the rain will end by the time I get out of work......

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Drained the tank last night after work, siphoned from the top rather than from the bottom - it was getting dark and I didn't have a lot of time. Tilting the tank up helped. Fresh gas today and we'll try to start it.......

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Added ~1.5 gallons of fresh gas (non-ethanol flavor), hit the starter button and........same result. Cranks, but no combustion :mad:

 

Maybe I didn't siphon all the bad gas?  I don't know what the interior of the tank looks like, maybe the siphon can't get to the lowest portion and I'm just pouring good gas over the bad. Probably will remove the tank, drain it and try again.

 

Question - what do you do with gas you don't want to use in your auto?

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The FI self-diagnosis system will catch any faulty sensors (IAT, TPS, MAP etc) but is not looking at the fuel pressure, or flow. My guess is that you are not getting sufficient fuel  at the injectors, hence the reluctance to rev out, and that whatever caused that has got worse so it now won't start. If replacing the fuel doesn't help, you can try running the pump with the return line from the fuel rail disconnected at the tank (and the tank nipple capped) and aimed into a bucket, and confirm there is good flow (spec = 150 ml in 10 sec). You can jumper the pump at the fuel cut relay (to the RHS of the oil cooler in the nose) by connecting the brown and black/white terminals in the harness. 

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  • 3 weeks later...
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Wanted to update everyone in case others have the same symptoms (plus I hate threads that end without a solution)

 

I ran out of time to troubleshoot and brought the bike to the local dealer (I'm not a big fan of theirs but there aren't a lot of alternatives). The mechanic zeroed in on the fuel pump - the pump spins (we knew that, heard the whine at start up) but does not deliver sufficient pressure.

 

Now the bike is waiting for a fuel pump :sad: seems the OEM Honda part is sold out and won't be available for some time so I went with an aftermarket part. Hopefully will be riding next weekend

 

 

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